Discover the IHRDC Energy Glossary_beta

S w

Water saturation — the fraction of pore space occupied by water.

S-wave

A shear wave: a body wave whose particle motion is perpendicular to its direction of travel, able to pass only through material with shear strength.

s.g.

Specific gravity — the density of a substance divided by that of fresh water at a stated temperature.

sabkha

An Arabic word for flat, salt-encrusted areas that are subject to periodic flooding and evaporation. Sabkhas are supratidal, forming along arid coastlines, characterized by evaporite-carbonate deposits with some siliciclastics and the accumulation of aeolian clays, evaporites, and salts.

sack

The standard bulk unit of cement, 94 lb in the US, against which additive concentrations are quoted.

sacrificial anode

A method of cathodic protection.

saddle bearing

A bearing located on top of the sampson post. The saddle bearing supports the walking beam and allows it to pivot.

safe work procedure

The written method for a task, specifying the precautions that make it safe to perform.

safeguard

Any control interposed between a hazard and its consequence.

safety belt

A belt securing a driver or passenger to their seat as a precaution against injury in a crash.

safety clamp

A clamp fitted around a flush tubular or toolstring so it cannot fall through the slips or the stripper while being handled.

safety culture

The shared attitudes that decide what people actually do when nobody is watching.

safety data sheet (SDS)

A 16-section document that contains information on the specific hazards of a chemical, its health effects and treatment, clean-up instructions, and other information.

safety fuse plugs

A device on a compressed as cylinder that releases gas in the event of a fire to prevent an explosion.

safety glasses

Glasses, usually with side shields, that meet the minimum recognized standards for impact resistance.

safety hazard

A condition able to cause harm.

safety head

The flanges and fittings used to hold a rupture disc; another name for rupture disk assemblies.

safety instrumented system

Instrumentation that takes the process to a safe state automatically when limits are exceeded.

safety interlock system

A security fence, security key, and switch that serve to isolate a capacitor bank.

safety joint

A connection built into a string so it can be deliberately parted at a known point if the assembly below becomes stuck.

safety precaution

A measure taken before work to remove or control a hazard.

safety protocol

The written procedure governing a hazardous operation, and the control regulators actually audit.

safety relief valve

A valve that can be used as either a safety valve or a relief valve, depending on the application.

safety spacer

A blank gun section placed between the top perforating gun and the firing head in a tubing-conveyed operation.

safety switch

Usually, a knife-type switch that is manually operated by means of a handle and linkage.

safety valve

An automatic pressure relief device that pops open quickly to relieve excess pressure in a system containing steam or gas, venting to the atmosphere. Commonly used in gas and steam systems.

safety valve scssv

The surface-controlled subsurface safety valve, which shuts the well in from surface.

safety-sensitive job

A role where impairment would endanger others, justifying additional testing and controls.

sag

The settling of weighting material out of the mud, leaving a light column above and a heavy slug below.

sag ponds

A body of fresh water collected in the lowest parts of a depression formed between two sides of an active strike-slip, transtensional or normal fault zone.

SAGD

Steam-assisted gravity drainage: a horizontal steam injector above a parallel horizontal producer, so heated bitumen drains under gravity into the lower well.

sales and operations planning (S&OP)

The regular cross-functional process reconciling demand plans with supply capability.

Sales and Purchase Agreement (SPA)

The long-term LNG contract fixing volumes and pricing, and the basis on which projects are financed.

sales gas specification

The contractual limits on water, sulfur and heating value that gas must meet to be sold.

sales, production and COGS budgets

The linked budgets deriving production and cost of goods sold from the sales forecast.

salient-pole rotor

A type of rotor, primarily used in low-speed applications, that has windings wrapped around metal pole pieces.

saline

Having some dissolved salt content.

salinity

The saltiness, or dissolved salt content, of water.

salinity, saline

Salinity is the saltiness, or dissolved salt content, of water.

salt

Halite, a soft soluble evaporite mineral that flows under load and is less dense than compacted sediment.

salt cavern

A void solution-mined in a salt bed and used for high-deliverability storage.

salt cavern storage

A storage facility that cycles gas in and out of underground caverns leached, brined or mined in either bedded salt or a salt dome.

salt diapir

A salt body that has risen through its overburden.

salt dome

A plug or mushroom of salt that has risen buoyantly through the overlying section, often carrying a cap rock.

salt halite

Rock salt, which flows plastically and forms diapirs and seals.

salt plug

A temporary barrier formed from graded salt granules, which later dissolve in undersaturated fluid.

salt proximity survey

A borehole seismic survey that locates the salt-sediment interface beside a well by timing energy refracted along it.

salt-proximity vertical seismic profile (VSP)

A VSP shot to locate the salt flank relative to a well, using energy refracted through or reflected off the interface.

saltwater flow

An influx of saline formation water into the wellbore, particularly from shallow overpressured sands.

saltwater mud

A water-base mud whose continuous phase carries substantial dissolved sodium chloride.

sample

A small representative quantity of gas or liquid obtained for analysis.

sample analysis

The procedure which measures the components, contaminants and/or BTU value of a natural gas or liquid stream.

sample container

The vessel a sample is collected and transported in.

sample cylinder

A pressure device with which natural gas and liquid samples are collected; typically made of stainless steel.

sample frequency

How often samples are taken, per unit of depth or time.

sample interval

The distance or time between successive samples.

sample point

The raw data from an analog to digital converter used to calculate waveform points.

sample probe

The insert drawing a representative sample from a flowing stream, positioned to catch the mixture and not the wall film.

sample rate

The number of samples taken per unit time, the reciprocal of the sample interval.

sampler

A device on the LACT unit which collects and maintains a sample of the liquid passing through the unit.

sampling error

The uncertainty introduced by measuring only part of a population rather than all of it.

sampling interval

The spacing in depth or time between successive readings taken by a sensor.

sampling line

The tubing carrying sample from probe to container, kept short and heated where the sample could drop out.

sampling method

The procedure by which a sample is taken, which affects the result as much as the analysis does.

Sampson post

The structure that supports the beam.

sand

A detrital grain between 0.0625 and 2 mm across, and by extension a rock made of such grains.

sand bailer

A slickline tool that collects sand or fill from the bottom of the well and brings it to surface.

sand cleanout

The removal of sand fill from the wellbore, usually by circulating it out with coiled tubing.

sand consolidation

A chemical treatment that bonds formation sand grains in place so they cannot be produced.

sand control

Any equipment or technique used to stop formation sand entering the wellbore with the produced fluids.

sand lense

An isolated sand body enclosed in finer sediment, forming a stratigraphic trap.

sand lifting

Removing sand or fill from a wellbore by circulating it out to surface.

sand line

A small-diameter wire rope on the rig drawworks, used for swabbing, bailing and running light tools.

sand lobe

A depositional body of sand, typically at the mouth of a channel or fan.

sand production

The movement of formation sand into the wellbore with the produced fluid.

sand reservoir

Reservoir in sand or sandstone.

sand ridge

An elongate shelf sand body built by currents.

sand test

The API test measuring the volume percent of a mud retained on a 200-mesh screen.

sand trap

An unstirred compartment just downstream of the shakers where coarse solids that got past the screens settle out.

sand-shale sequence

An alternation of sand and shale beds.

sandface

The physical interface between the formation and the wellbore.

sandface pressure

The pressure at the face of the formation, which sets the actual drawdown.

sandland (integrated petroleum simulation)

The integrated petroleum simulation, developing an oil company in a fictional West African country.

sandout

The premature bridging of proppant in the fracture or wellbore, so that no more solids can be placed.

sandstone

A clastic sedimentary rock (also called arenite) composed of sand-sized minerals and rock grains, most commonly quartz and/or feldspar.

sandstone formation

A named rock unit composed of sandstone.

sandstone line for spontaneous potential

The sandstone line on a Spontaneous Potential (SP) curve is established by the position of the SP curve opposite clean, permeable formations.

sandstone petrography

The microscopic description of a sandstone's grains, matrix, cement and pore space.

sandstone porosity

The pore fraction of a sandstone.

sandstone porosity unit

Neutron porosity reported on a sandstone matrix calibration rather than a limestone one.

sandstone reservoir

Reservoir in sandstone, where porosity is between grains and is fairly predictable.

sandstone, sand

Sandstone, or arenite, is a clastic sedimentary rock composed of sand-sized minerals and rock grains. Most sandstone is composed of quartz and/or feldspar.

sandstone, sand, siliciclastic

A clastic sedimentary rock (also called arenite) composed of sand-sized minerals and rock grains, most commonly quartz and/or feldspar.

sandstone, sand, siliciclastic, silica

Sandstone, or arenite, is a clastic sedimentary rock composed of sand-sized minerals and rock grains. Most sandstone is composed of quartz and/or feldspar. Often, in the oil industry, the terms sandstone and sand are incorrectly used interchangeably.

sandstone-compatible scale

Density and neutron scales set so the curves overlie in a clean water-filled sandstone.

SAPP

Sodium acid pyrophosphate: a phosphate deflocculant used to thin low-temperature water muds and to treat cement contamination.

saprolite

Saprolite is a soft, earthy, and thoroughly decomposed rock, often rich in clay, that is formed in situ by the chemical weathering of igneous, metamorphic, or sedimentary rocks that retains some of the original rock's structures.

SARA analysis

Fractionation of a crude into saturates, aromatics, resins and asphaltenes, abbreviated SARA.

Sarbanes-Oxley Act

The United States statute imposing financial reporting and internal control obligations after Enron.

SASB (Sustainability Accounting Standards Board)

The standards setting industry-specific sustainability metrics for investors.

satellite platform

A small unmanned platform tied back to a main host facility, which does the processing and export.

saturant

The fluid occupying the pore space.

saturated air

Air that is holding its maximum amount of water vapor.

saturated gas

A gas stream which contains the maximum water vapor at its operating conditions.

saturated molecule

A molecule whose structure is such that no additional atoms may be added to it.

saturated solution

A solution containing as much solute as it can dissolve at a given temperature and pressure.

saturating

Filling the available pore space with fluid.

saturating transformer

A device in a pilot wire relay that limits the voltage output that is impressed on the pilot wires in a pilot wire relaying system.

saturation

A state in which an increase in the input signal to an amplifier causes no further increase in output; the output is at or near the supply voltage.

saturation equation

The relation used to compute water saturation from resistivity, porosity and formation water resistivity.

saturation exponent

The exponent n relating resistivity index to water saturation, typically about 2 in water-wet rock.

saturation exponent (n)

The exponent n in the relation of water saturation (Sw) to resistivity index (I) where I = Sw⁻ⁿ. It expresses the effect on resistivity of desaturating a rock sample, or replacing water with a non-conductive fluid.

saturation temperature

The temperature at which water will boil at a given pressure.

saturation unit

One percent of pore volume occupied by a given fluid.

saturation value

The fraction of pore space a phase occupies.

save

The process of uploading a project from a PLC to a PC or to an EEPROM.

saver sub

A short sub run between the kelly or top drive and the drillstring, so wear falls on it rather than on the expensive component above.

sawtooth and triangle waves

Waves that result from circuits designed to control voltages linearly, such as the horizontal sweep of an analog oscilloscope. The transitions between voltage levels of these waves change at a constant rate. These transitions are called ramps.

SBR

Synthetic/brine ratio — the proportion of synthetic base fluid to brine in the liquid phase of a synthetic mud.

SC connector

A type of optic cable connector that snaps straight into equipment.

SCADA (Supervisory Control and Data Acquisition)

The system collecting field data and issuing control commands across a dispersed facility.

SCADA system

Supervisory Control and Data Acquisition system that collects data on process or production, and issues automated control decisions to local equipment controllers.

scaffold

An elevated work platform for personnel and materials.

SCAL

Special core analysis: laboratory flow experiments on core plugs that measure relative permeability, capillary pressure, wettability and electrical properties.

scale

A deposit or coating formed on the surface of metal, rock, or other material due to precipitation from chemical reactions or changes in pressure, temperature, or solution composition. Can build up on the insides of water tubes, pipes, and equipment, interfering with heat transfer and restricting flow. Also, the ratio between the size of an object on a drawing and its actual size.

scale inhibitor

A chemical that stops scale-forming minerals from crystallizing, or keeps the crystals too small to adhere.

scale inhibitor squeeze

Pumping scale inhibitor into the formation so it adsorbs on the rock and releases slowly back into the produced water.

scale inhibitors

Chemicals added to cooling water to protect equipment from scale formation.

scale removal

The mechanical or chemical clearing of deposited scale from tubing, perforations and near-wellbore rock.

scallop gun

A hollow carrier gun with recesses machined opposite each charge, so the wall is thinner where the jet must pass.

scan cycle

The three-step process that a PLC uses to perform its job: scan the inputs, perform the program logic, and set the outputs.

scan time

How long a programmable controller takes to execute its logic once.

scanning electron microscope (SEM)

A scanning electron microscope is a type of electron microscope that produces images of a rock sample by scanning it with a focused beam of electrons. The electrons interact with atoms in the rock, producing various signals that can be detected and that contain information about the rock's composition.

scarp

A steep face produced by faulting or erosion.

scattered noise

Energy returned from small irregularities, which cannot be stacked out because it is not coherent.

scatterer

A small feature that returns seismic energy in all directions, producing a diffraction.

scattergram

A plot of one variable against another as unconnected points, showing how the two relate.

scavenger

An additive that reacts with a contaminant in a fluid to convert it into a harmless compound.

SCC

Stress corrosion cracking: brittle cracking of a susceptible metal under the combined action of tensile stress and a specific corrosive environment.

scenario analysis

Testing coherent combinations of assumptions rather than moving variables independently.

scenario planning

Preparing for several plausible futures rather than forecasting one.

schedule

The dimensionless number that specifies a pipe's wall thickness for a given nominal size.

schedule control

Tracking progress against plan and acting on the variance early enough to matter.

schein's decision-making strategies

The range of ways a group can decide, from unilateral to full consensus.

schematic

A schematic is a diagram that represents the elements of a system using abstract, graphic symbols rather than realistic pictures.

schematic diagram

A drawing that uses symbols to show the electrical connections and functions of a specific circuit arrangement, with components shown in their proper electrical locations. Also called an elementary diagram.

schematic symbol

The drawing convention representing a component.

schlumberger

The largest oilfield service company.

scientific notation

The expression of a quantity as a decimal number times a power of ten.

scintillation counter

A scintillation counter is a device for detecting and recording scintillations, especially in order to measure ionizing radiation.

scintillation detector

Scintillation detectors use crystals that emit light when gamma rays interact with the atoms in the crystals. The intensity of the light produced is proportional to the energy deposited in the crystal by the gamma ray.

scope

Everything the project will produce, and by implication everything it will not.

scope 1, 2 and 3 emissions

Direct emissions, those from purchased energy, and those across the value chain including product use.

scope creep

Incremental additions to scope that are never formally approved or funded.

scope definition

Fixing precisely what is and is not included, the single biggest driver of cost certainty.

scope of work

The precise statement of what the contractor must deliver.

SCORM

The long-standing standard letting course packages run in any conforming platform.

Scotch yoke

A slotted-link mechanism converting a piston's linear stroke into the quarter turn of a valve stem.

Scottish qualifications authority (SQA)

The national accreditation and awarding body for Scotland. Its purpose is to help people fulfill their potential and maintain standards across Scottish education. SQA engages with learners, schools, colleges and training providers across Scotland, the rest of the UK and internationally, to develop, maintain, and improve a framework of qualifications, and to set and maintain standards for many other awarding bodies and accredited qualifications.

Scottish vocational qualification (SVQ)

SVQs are work-based qualifications that work as a guarantee that someone can do their job well and to the national standards for their sector. Qualifications in the oil and gas sector include, among others, Instrument and Control Technicians, Electrical Technicians, Mechanical Technicians, Control Room Operators.

scour

Erosion by flowing water, which cuts into the underlying bed and marks the base of a channel.

scour and fill

Scour and fill refers to a structure that has been eroded by water flow and has then been filled with coarse sediment over time.

scout

To gather information on another operator's activity in an area, or the person who does so.

scout ticket

A one-page summary of a well's permit, drilling, testing and completion history.

SCR

Silicon-Controlled Rectifier. A silicon device with four PNPN layers having an input control terminal (gate), an output terminal (anode), and a terminal common to both (cathode). A high-speed, solid-state switch used in variable speed drives and for lighting/heating control.

scraper

A utility pig fitted with blades or brushes to clean deposits from the inside of a pipeline.

scraper rings

Rings on the piston rod which remove lubricants.

scraper trap

A pipeline launcher or receiver — a barrel with a closure through which a pig is inserted or removed under isolation.

scrapers

Tools run to clean scale, cement or debris from the inside of casing.

scratcher

A device fitted to casing that scrapes mud cake off the borehole wall as the string is moved during cementing.

scratchers

Devices on casing that scrape mud cake from the hole so cement can bond.

screen

An air cleaning device to prevent large contaminants from entering a system. Also, a device installed upstream of a pump or compressor to keep solid material from entering the suction.

screen out

A condition that occurs when the solid proppant carried out in fracture treatment fluid creates a bridge across the perforations or similar restriction flow area.

screen time

Hours spent at displays, relevant to eye strain, posture and rest.

screening

A first-pass assessment of whether a reservoir suits a particular recovery process, before detailed study.

screw

A threaded fastener with a nail-shaped or rod-shaped body and a slotted or recessed head. A screw is designed to be inserted into material by rotating, and is used for fastening pieces of solid material together.

screw pump

A rotary positive displacement pump that uses one or more screws to move fluid.

scrub

To clean a gas stream by contacting it with a liquid that absorbs the contaminants out of it.

scrubber

A device or vessel that uses absorption, spray, or other methods to remove impurities and contaminants from a gas, vapor, or exhaust stream. In amine treatment, a component that removes amine solution carried by sweetened gas.

scrubber liquid level

The liquid level in a scrubber, whose rise means the drain has failed and carryover is next.

scrubber oil

Liquid hydrocarbon knocked out of a gas stream in a scrubber and collected for recovery.

scrum

An agile framework organizing work into fixed-length sprints with defined roles and events.

scrum artifacts

The product backlog, sprint backlog and increment.

scrum cycle

The sprint loop from planning through daily coordination to review and retrospective.

scssv

Surface-controlled subsurface safety valve, which shuts the well in from surface.

sea floor

This effect can also occur in fresh water bodies, but for consistency, we have chosen to use the term 'sea floor' in this section.

seabed geophone

A geophone placed on the sea floor, usually with a hydrophone, to record seismic data at the water bottom.

seal

A layered lithological unit capable of impeding hydrocarbon movement, typically thick, laterally continuous, ductile rock with high capillary entry pressure. Also, any device for eliminating or controlling fluid flow between areas.

seal assembly

A stack of seals on the end of a string that engages a polished bore to isolate the tubing from the annulus.

seal gas

Dry, clean, higher pressure gas supplied between labyrinth seals of the expander-compressor to prevent process gas from reaching the bearings or lubrication system.

seal receptacle

A polished internal profile built into a completion string to receive a mating seal assembly.

seal, sealing fault

A seal is a layered lithological unit capable of impeding hydrocarbon movement. Effective seals for hydrocarbon accumulations are typically thick, laterally continuous, ductile rocks with high capillary entry pressures. Faults can be seals.

sealbore

The machined, polished internal surface a seal assembly seals against.

sealbore packer

A permanent packer with a polished bore through it, into which the tubing's seal assembly stabs.

sealing line

The line of contact that makes a seal.

sealing surface

The face that makes a seal.

seals

The low-permeability rock units that hold hydrocarbons in a trap and separate one fluid compartment from another.

search

A software troubleshooting tool that allows you to find specific instructions in a program.

search angle

Search angle defines how far up and down the hole the computer matching process seeks a correlation and, depending on the hole size, reflects the analyst's initial estimate of the highest expected dip.

search engine marketing (SEM)

Buying visibility in search results, as distinct from earning it.

search engine optimization (SEO)

Improving a site so it ranks higher in unpaid search results.

seasonal gas

Gas supply or storage used to meet winter demand.

seasonal market

A market whose demand varies systematically through the year.

seasonal swing

The variation between summer and winter demand, which storage exists to absorb.

seasoning new wireline logging cable

Seasoning is the process of balancing cable torque in a new wireline logging cable.

seat

A stationary part of a valve onto which a disc or other flow control component presses to stop flow through the valve.

seating area

The contact area between a valve closure member and its seat.

seating nipple

A profiled short tubular in which a pump or downhole device lands and seals.

seating surface

The face a valve closure member seats against.

seaward

Toward the basin, the direction in which prograding sediment builds.

seawater mud

A water-base mud mixed on seawater, so its base fluid already carries about 35,000 ppm of dissolved salts.

second chance agreement

A documented condition of continued employment following a substance policy breach.

secondary burn

See Proof burn.

secondary cementing

Cementing carried out after the primary job to repair it or to deal with a later problem.

secondary coil

The coil in a transformer in which an EMF is induced.

secondary element

Part of a meter station, consisting of the meter piping, meter manifold, recording devices, and associated measurement equipment such as static pressure recorders, density meters, and samplers.

secondary loop

The inner, or slave, control loop in a cascade control system that controls its variable according to a set point provided by the primary loop.

secondary migration

The movement of expelled hydrocarbons through carrier beds and faults into a trap.

secondary porosity

Porosity created after deposition and burial through alteration of rock by mechanical processes (compaction, deformation, fracturing) and geochemical processes (dissolution, dolomitization, precipitation, volume reductions by mineralogical changes).

secondary porosity index

The secondary porosity index is an indicator of the porosity that does not contribute to a sonic measurement of interval transit time. The transit time is little affected by vugs, fractures and other irregular events because the sonic wave finds a faster path around them. Spherical pores such as oomolds also have less effect on travel time than oblate pores. Thus, when the sonic porosity is less than some measurement of the total porosity, the difference can be attributed to the presence of post-depositional, or secondary, porosity.

secondary production

Production supported by injecting water or gas to maintain pressure once natural energy has declined.

secondary recovery

Secondary recovery technique refers to any method for removing oil from a reservoir after all natural recovery methods have been exhausted.

secondary reflection

Seismic energy that has been reflected more than once before reaching the receiver.

secondary superheater

The second superheater stage, taking steam to its final temperature.

secondary supervisor

Supervisors may assign an employee's competency role to another user with Supervisor permissions in order to have that person - called a secondary supervisor - complete all or part of the supervisor assessment. One example might be where the secondary supervisor is a subject matter expert in a safety critical competency. The primary supervisor will need to review and submit any assessment completed by a secondary supervisor. Although the secondary supervisor will mark an assessment complete when finished, it will not be finalized until the primary supervisor submits it.

secondary term

The period after a lease's primary term during which it stays alive so long as production or the specified operations continue.

secondary voltage

The voltage on a transformer's output winding.

secondary winding

The winding of a transformer into which voltage is induced and to which a load is connected.

secondee

An employee placed temporarily with a partner, venture or government while remaining on the home payroll.

section

A subdivision of a part in the NEC.

section drawing

A cutaway drawing that shows the inside of a building or an object.

sectionalizer

Operates when a line is "dead" due to the operation of a reclosing relay or circuit breaker in order to isolate a section of line while allowing the remainder of the circuit to remain energized.

security awareness training

Training staff to recognize and respond to threats, since most breaches begin with a person.

security breach

An incident in which controls failed and information was exposed or systems compromised.

security control

Any measure implemented to reduce a security risk.

security governance

The structure of accountability and policy directing how security is managed.

Security Vulnerability Assessment (API RP 780)

The industry recommended practice giving a standard method for that assessment.

sediment

Loose material — mineral grains, rock fragments or organic matter — transported by water, wind or ice and deposited.

sediment accumulation

The build-up of sediment through time.

sediment fill

The sediment that has filled a basin or a channel.

sediment load

The sediment a current carries, and the weight that drives basin subsidence.

sediment source

The area sediment was eroded from and supplied by.

sedimentary

Pertaining to rock formed by the deposition and lithification of sediment, one of the three main rock classes.

sedimentary basin

A region of prolonged crustal subsidence in which a thick sedimentary fill accumulates.

sedimentary cover

The sedimentary section overlying basement.

sedimentary environment

The physical setting sediment was deposited in, which controls grain size and geometry.

sedimentary particle

A grain transported and deposited to form sedimentary rock.

sedimentary rock

Rock formed from deposited particles or precipitates, in which nearly all petroleum is found.

sedimentary rock property

A measured attribute of sedimentary rock such as porosity or permeability.

sedimentary sequence

A succession of sedimentary strata.

sedimentary structure

A feature formed in sediment as it was laid down, from which flow conditions can be read.

sedimentation

The whole process by which sediment is produced, transported and laid down.

sedimentological

Concerning the deposition and character of sediment.

sedimentology

The study of sediments such as sand, silt, and clay, and the processes that result in their formation, transport, deposition, and diagenesis.

seeding

Adding crystals to a solution to cause new crystals to form around them.

seep

A natural leak of oil, gas or water at the surface, from a subsurface accumulation or source.

seeps

Natural surface leakage of oil or gas, historically the first sign of a petroleum system.

segmentation (web)

Splitting site visitors into groups whose behavior can be compared.

seif dune

A seif dune is a long, narrow sand dune or chain of dunes, generally oriented in a direction parallel to the prevailing wind.

seismic

Pertaining to elastic waves in the roughly 1 to 100 Hz band used to image the subsurface.

seismic acquisition

The field work of generating seismic energy and recording the returning wavefield.

seismic amplitude

The strength of a reflection, which carries information about rock and fluid contrast.

seismic attribute

A quantity derived from the seismic trace, used to infer rock or fluid property.

seismic crew

The field party acquiring a seismic survey.

seismic data

Seismic data is comprised of sound (seismic) wave recordings of Earth's subsurface that are obtained in seismic surveys. Seismic waves are generated by specialized equipment that reflects off subsurface rock layers which are then are captured by recording equipment. The data are processed and interpreted to provide a "picture" of the subsurface geology in either 2D (single slice) or 3D (volume) formats, depending on the survey design.

seismic data (3D and 2D)

3D seismic data is a set of numerous, closely spaced seismic lines that provide a high spatially sampled measure of the subsurface reflectivity. 2D seismic data is a group of 2D seismic lines acquired individually, as opposed to the multiple, closely spaced lines acquired together in 3D seismic data.

seismic data processing

The computational sequence turning field records into an image.

seismic energy

The elastic energy put into the ground and recovered as reflections.

seismic exploration

Searching for prospects using reflection seismic data.

seismic expression

How a geological feature appears in seismic data, which is rarely how it appears in rock.

seismic facies

The character of a reflection package, used to infer depositional environment.

seismic image

The processed picture of the subsurface.

seismic imaging

Turning recorded reflections into a picture of the subsurface in its correct position.

seismic impedance

The product of density and velocity in a rock layer, the property whose contrast produces reflections.

seismic interpretation

The derivation of subsurface structure and stratigraphy from processed seismic data.

seismic line

A display of seismic data along a single traverse, whether acquired in 2D or extracted from a 3D volume.

seismic method

The technique of imaging the subsurface with reflected elastic waves.

seismic migration

Repositioning reflections to where the reflecting rock actually is, rather than where the energy was recorded.

seismic modeling

The forward calculation of the seismic response an assumed earth model would produce.

seismic processing

The sequence of operations that turns field records into an interpretable image — noise suppression, deconvolution, stacking and migration.

seismic profile

A section of seismic data along a line.

seismic pulse

The short wavelet the source puts into the ground.

seismic record

All the traces recorded from one shot.

seismic reflection

The return of seismic energy from an interface, the basis of subsurface imaging.

seismic reflection tomography

Inversion of reflected traveltimes from many source-receiver pairs into a three-dimensional velocity model.

seismic reflector

An interface producing a recorded reflection.

seismic refraction method

A survey that measures energy critically refracted along a high-velocity layer, giving that layer's velocity and depth.

seismic resolution

The smallest feature the data can separate, set by bandwidth rather than by sample rate.

seismic response

The reflection a given rock and fluid arrangement produces, which is what interpretation works backward from.

seismic section

A display of processed seismic traces side by side along a line, in time or depth.

seismic sequence

A package of reflections bounded by unconformities, interpreted as one depositional episode.

seismic signal

The part of the record carrying subsurface information, as opposed to noise.

seismic source

The device putting energy into the ground, whether vibrator, airgun or explosive.

seismic stratigraphy

The interpretation of depositional sequences and their environments from reflection geometry on seismic data.

seismic survey

Technique for determining the structure of underground rock formations by sending energy waves or sound waves into the earth and recording the time it takes for waves to reflect back to the surface. Three-dimensional (3D) seismic surveys provide enhanced subsurface images for selecting well locations.

seismic time

Two-way travel time, the vertical axis seismic data is recorded on.

seismic trace

The recorded time series for a single channel.

seismic velocity

The speed at which a seismic wave travels through rock, distance divided by traveltime.

seismic vessel

The ship towing sources and streamers for marine acquisition.

seismic wave

A disturbance that carries elastic energy through rock by moving particles about their rest positions, without transporting the rock itself.

seismic wavelet

The short pulse convolved with the earth's reflectivity to make the recorded trace.

seismic-while-drilling vertical seismic profile

A VSP recorded during connections, with a surface source and receivers in the bottomhole assembly.

seismite

A sedimentary bed deformed or injected by earthquake shaking.

seismogram

The recorded traces from a single shotpoint, displayed together.

seismograph

An instrument that detects and records ground motion, whether from earthquakes or from an exploration source.

seismology

The study of elastic waves in the Earth and of what their propagation reveals about its structure.

seismometer

A sensor that converts ground motion into an electrical signal for recording.

select carcinogen

Any substance which meets one of the following criteria: (i) It is regulated by OSHA as a carcinogen; or (ii) It is listed under the category, "known to be carcinogens," in the Annual Report on Carcinogens published by the National Toxicology Program (NTP) (latest edition); or (iii) It is listed under Group 1 ("carcinogenic to humans") by the International Agency for Research on Cancer Monographs (IARC) (latest editions); or (iv) It is listed in either Group 2A or 2B by IARC or under the category, "reasonably anticipated to be carcinogens" by NTP, and causes statistically significant tumor incidence in experimental animals in accordance with any of the following criteria: (A) After inhalation exposure of 6-7 hours per day, 5 days per week, for a significant portion of a lifetime to dosages of less than 10 mg/(3); (B) After repeated skin application of less than 300 (mg/kg of body weight) per week; or (C) After oral dosages of less than 50 mg/kg of body weight per day.

selective azeotropic solvents

Solvents that form azeotropes with only certain types of compounds.

selective control

A control system in which the numbers of controlled and manipulated variables are unequal; a method of sharing variables.

selective coordination

The process of isolating a faulted circuit from the rest of an electrical system by the proper selection of overcurrent protective devices within the system.

selective firing

Firing individual guns of a multi-gun string separately rather than all at once.

selective nipple

A landing nipple that can be run several times in one string, with a device landed in whichever one is wanted.

selective perforating

Choosing which intervals of a multi-gun string to fire, so only the wanted sections are opened.

selective running tool

A tool that sets or retrieves a device in whichever of several identical nipples is chosen, rather than the first one it reaches.

selectivity

The differing degrees of attraction that different ions have to resin bead sites. Also, the ability of a catalyst to select certain hydrocarbon components for reaction.

selector

A control device that selects one input from two or more inputs on the basis of comparative magnitude; for example, a high selector or low selector.

selector switch

A switch choosing between several modes or sources.

self-assessment or employee assessment (EA)

An employee uses CMS Online software to indicate his competency level for each Competency Unit by checking the box next to the skills that he can perform.

self-contained breathing apparatus

An air-supplied respirator that provides clean air from tanks for breathing. Also referred to as an SCBA.

self-contained breathing apparatus (SCBA)

Personal protective equipment that supplies users with breathable air from a compressed air tank that is typically worn on the user's back.

self-cooled power transformer

A power transformer that is cooled by the natural circulation of oil and air.

self-cooled/forced-air cooled power transformer

A power transformer that is cooled by the natural circulation of oil and the forced circulation of air.

self-induction

A type of induction that occurs within a single conductor; it occurs when a change in the electromagnetic field around a conductor induces a voltage in that conductor.

self-paced course

A course the learner works through on their own schedule.

semblance

A normalized measure of trace-to-trace coherence, the stacked energy divided by the summed energy of the input traces.

semi-open impeller

An impeller that has a shroud on only one side of the vanes.

semiconductor device

A component whose conduction is controlled, the basis of all modern electronics.

semilog

A plot with one logarithmic axis, on which pressure transient data forms a straight line.

semilog straight line

The straight portion of a pressure transient plot, from which permeability is calculated.

semiregenerative reforming

A type of catalytic reforming in which the catalyst is regenerated inside the reactors while the unit is shut down.

semisubmersible

A floating drilling vessel supported on submerged pontoons, so most of its buoyancy sits below wave action.

sendout

The rate at which an LNG terminal delivers gas into the network.

sensible heat

Heat that is transferred during a temperature change.

sensible heat transfer

A heat transfer process that causes a measurable change in temperature rather than a phase change.

sensing device

A device that responds to the condition of a process variable.

sensitive volume

The region from which an NMR signal will preferentially be acquired because of strong magnetic field inhomogeneity elsewhere.

sensitivity

The difference between the MON and RON of a given gasoline. Gasoline with high sensitivity is more affected by changes in engine operating conditions than is gasoline with low sensitivity.

sensitivity analysis

Varying one input at a time to see which assumptions the answer actually depends on.

sensitizer

A chemical that causes an allergic reaction in normal tissue after repeated exposure to the chemical.

sensor

A transducer whose purpose is to sense or detect some characteristic of its environment.

sentiment analysis

Automatically classifying the opinion or attitude expressed in a piece of text.

separately excited

A DC motor in which the armature windings and the field windings are not energized by the same source.

separating people from the problem

Dealing with the relationship and the substance on separate tracks.

separation facility

The plant separating produced fluids into saleable phases.

separator

A vessel that allows gas to separate from liquids, or in which different components settle out according to their different densities. Also called a settling tank, accumulator, or receiver.

separator backpressure

The pressure held on a separator, which the well must overcome for its fluids to enter.

separator function

What a given separator is there to do, since vessels that look alike may split two phases or three.

separator gas

The gas stream leaving a separator after the liquid has been dropped out of the wellstream.

separator pressure

The pressure a separator is held at, which decides how much gas flashes off and how much liquid is recovered.

sepiolite

A needle-shaped magnesium silicate clay used to viscosify muds where bentonite will not work.

sequence

A relatively conformable succession of strata bounded above and below by unconformities or their correlative conformities.

sequence boundary

The unconformity, or its correlative conformity, that separates one depositional sequence from the next.

sequence filter

A device in a pilot wire relay that converts three-phase current inputs into a single-phase voltage output.

sequence stratigraphic

Relating to the interpretation of strata as cycles bounded by surfaces of erosion or flooding.

sequence stratigraphic surface

A bounding surface within a depositional sequence.

sequence stratigraphy

The study of genetically related strata within a framework of surfaces of erosion or non-deposition and their correlative conformities.

sequence valve

A pressure control valve that senses pressure changes to control the sequence of operation of two separate components.

sequencing

A discrete control function that allows events to take place only in a particular order.

sequencing chart

A chart that shows the positions of a motor controller's components during various stages of controller operation.

sequential Gaussian simulation

A geostatistical method that fills a grid one cell at a time along a random path, drawing each value from a conditional distribution, abbreviated SGS.

sequestering agent

A chemical that binds a troublesome ion into a soluble complex so it cannot precipitate.

serial connection

A connection between racks or devices where data is transmitted one bit at a time. The physical medium is usually coaxial cable or a shielded twisted pair.

serial troubleshooting

A method of troubleshooting in which each component in a circuit or process is tested in sequence until the source of the problem is located.

sericite

Sericite is a fine-grained fibrous variety of muscovite, mainly found in schist.

series

A DC motor in which the armature windings and the field windings are wired in series and energized by the same source.

series circuit

A circuit that has only one path for current flow, with components connected end to end.

series motor

A DC motor in which the field coils are connected in series with the armature.

series reactor

Substation equipment used to limit rapid changes in current flow.

series regulator

A regulator that is in series with the load.

series-parallel circuit

A circuit that has both series and parallel current paths, with some components connected in series and some in parallel.

servant leadership

Leading by removing obstacles and serving the team's needs first.

service contract

An arrangement paying the contractor a fee for work done, with no entitlement to the hydrocarbons.

service level

The proportion of demand met from stock or within the promised time.

servo system

A system that employs proportional valves along with a system of feedback in a closed loop configuration.

set point

The desired limit or particular value at which a control loop attempts to maintain a process variable.

set rod

A rod that can be screwed in to disconnect limit switch gearing from motor operator gearing.

setpoint

The point at which a process loop should stabilize, typically established by supervisory controllers. Also, the commanded speed at which a variable speed drive is set to run.

setscrew

A screw locking a component to a shaft.

setting tool

The tool that carries a packer or plug to depth, sets it and then releases.

settlement

Final payment and closing out of a contract, financially or by delivery.

settling

The third stage of clarification, in which floc settles to the bottom of a settling basin, leaving clarified water at the top.

settling pit

An unstirred mud pit in which cuttings and sand drop out by gravity before the fluid returns to the active system.

settling rate

How fast a dispersed phase separates, set by density difference, droplet size and viscosity.

settling tank

A vessel in which suspended or emulsified phases separate under gravity over time.

settling time

The time required for an output voltage to settle within a specified error band of the final value after a step change at the input (also known as total response time). Also, the time it takes for water to separate from oil.

seven bases for leadership

The course's enumeration of those foundations, from expertise to relationship.

Seven Basic Quality Tools

The standard diagnostic set: cause-and-effect, checksheet, control chart, histogram, Pareto, scatter, flowchart.

seven stages of public speaking

The course's sequence from analyzing the audience through to handling questions.

severance

The legal separation of the mineral estate from the surface estate, so the two can be owned and conveyed apart.

severity

A measure of how much a hydrocarbon molecule is cracked during the cat cracking process.

sexual harassment

Unwanted conduct of a sexual nature, or conduct creating a hostile environment on grounds of sex.

SH-wave

A shear wave polarized so that its particle motion lies in the horizontal plane, perpendicular to the direction of travel.

shackle

A U-shaped connector with a removable pin used to connect or couple rope or chain to other pieces of rigging equipment. Sometimes called a clevis.

shading

The short-circuiting of a portion of an electromagnet by metal rings or coils in a protective relay.

shadow IT

Systems adopted by staff without the knowledge of the technology function.

shadow zone

A region from which no energy is recorded because it has been blocked or bent away by an intervening body.

shaft alignment

Bringing two shafts onto a common axis at operating temperature.

shaft bearing

The bearing supporting a shaft.

shaft centerline

The axis of a shaft.

shaft runout

Deviation of a shaft surface from true rotation.

shaft sleeve

A replaceable sleeve protecting the shaft where packing or a seal runs on it.

shaft voltage

The difference in voltage potential between the shaft of a motor and ground. Shaft voltages can cause lubricant failure and bearing failure, and they can affect the stability of motor flux fields during the operation of a variable speed drive.

shaker

Short for shale shaker, the vibrating screen that makes the first and largest cut of drilled solids out of the returning mud.

shale

A fine-grained, fissile, detrital sedimentary rock formed by consolidation of clay- and silt-sized particles into thin, relatively impermeable layers. Certain shale formations (such as the Eagle Ford and Barnett) contain large amounts of oil and natural gas.

shale baseline

The shale baseline is the average reading of the spontaneous potential (SP) log opposite the shale layers in a well. Opposite shales, the SP is relatively constant and changes only slowly with depth.

shale content

The proportion of shale in a rock, which lowers both porosity and permeability and confuses logs.

shale distribution

How shale is arranged in the rock, as beds, laminae or dispersed clay, which matters more than its total amount.

shale formation

A named unit of shale, whether seal, source or unconventional reservoir.

shale gas

Natural gas that is found trapped within shale formations.

shale interval

A depth range of shale.

shale layer

A bed of shale, which may seal the reservoir or merely baffle it.

shale model

The assumption made about how shale is distributed, which changes every saturation calculation.

shale oil

Shale oil is oil that is found trapped within shale formations.

shale play

A regionally extensive shale developed as a reservoir rather than as a source or seal.

shale reservoir

Shale produced as a reservoir in its own right, needing stimulation to flow at all.

shale resistivity

The resistivity of shale, used as a reference in log interpretation.

shale shaker

A shale shaker is a piece of equipment that is part of the solids-control equipment on a drilling rig. It has mesh grills used for separating the drill cuttings from the circulating drilling mud.

shale shakers

Components of drilling equipment (mesh grills) used as the first phase of solids control on a drilling rig, separating drill cuttings from the circulating drilling mud.

shale shavers

Shale shakers are mesh grills used for separating the drill, or ditch, cuttings from the circulating drilling mud.

shale swelling

Shale swelling is caused by clay (one of the major components of shale) absorbing water, usually from drilling fluid.

shale volume, volume of shale, Vsh

Shale volume (Vsh) is the volumetric percentage of shale within a formation, or in a specific interval of a formation.

shale, shaly

Shale is a fine-grained, fissile, detrital sedimentary rock formed by consolidation of clay- and silt-sized particles into thin, relatively impermeable layers.

shaliness

The proportion of clay in a formation, which suppresses apparent resistivity.

shallow laterolog

The resistivity curve reading the invaded zone close to the borehole.

shallow marine

Deposited in shallow sea, the setting of many good reservoirs.

shallow resistivity

A measurement of the rock nearest the borehole, compared with deep readings to detect invasion.

shallower

At lesser depth, and so generally at lower pressure and temperature.

shallowest

The least deep in a succession or a set of measurements.

shaly

Containing shale or dispersed clay within an otherwise clean rock.

shaly formation

A formation with significant clay, which complicates saturation calculation.

shaly sandstone

Sandstone with significant clay content, which complicates log interpretation of saturation.

shaped charge

An explosive with a conical metal-lined cavity, so detonation focuses its energy into a directed penetrating jet.

shared responsibility

The division of security duties between provider and customer, misunderstanding of which causes breaches.

shareholder value

The return delivered to owners, and the question of whether it is the only proper aim.

shareholder versus stakeholder model

Whether a company is run for its owners alone or for a wider set of interests.

shear

Deformation in which parallel planes slide past one another, or the stress that produces it.

shear fracture

A shear fracture refers to the breakage and/or disintegration of a rock formation due to the application of a strain force on its surface.

shear modulus

The elastic constant relating shear stress to the shear strain it produces, a measure of a material's rigidity.

shear pin

A calibrated brass or steel pin that holds a mechanism in place until a known force breaks it.

shear ram

A blowout preventer ram with hardened blades that cuts the pipe in the hole and then seals the bore.

shear rate

The velocity gradient across a flowing fluid — how fast one layer moves relative to the next.

shear stock

The bar or wire from which shear pins are cut, of a known and controlled shear strength.

shear strain

The angular distortion produced when parallel planes in a material slide past each other.

shear strength

Shear strength is the strength of a material against the type of yield or structural failure when the material fails in shear.

shear stress

The force per unit area acting parallel to a surface, resisting the sliding of adjacent fluid layers or rock planes.

shear velocity

Shear velocity is the velocity of shear waves.

shear wave

A shear wave (S wave) is an elastic body wave in which particles oscillate perpendicular to the direction in which the wave propagates. Shear waves travel more slowly than compressional waves (P waves) and cannot travel through fluids because fluids do not support shear. Interpretation of S waves can allow determination of rock properties such as fracture density and orientation, Poisson's ratio, and rock type by cross-plotting P wave and S wave velocities and by other techniques.

shear-seal BOP

A blowout preventer whose rams cut the workstring and seal the bore in the same stroke.

shear-strength measurement test

An API procedure using a shearometer tube and calibrated weights to measure the shear strength of a mud or a spacer.

shearing

Deformation by sliding along planes rather than by compression or extension.

shearometer

A thin-walled tube lowered into a mud sample, whose sinking under set weights measures the gel's shear strength.

sheathed capacitance probe

A singular capacitance probe that uses a tubular metal shell and a metal inner rod as the two plates of the "capacitor."

sheave

A grooved wheel or pulley used for changing a rope's direction of travel.

sheave, sheave wheel

A sheave is a pulley used for running wireline tools into the wellbore. During wireline operations, two sheaves are temporarily hung in the derrick, and the wireline is run from the logging truck through the sheaves and then down to the logging tool in the wellbore.

sheaves

The grooved wheels a belt or rope runs in.

sheen

The thin iridescent film oil forms on a water surface, used as a field indicator of hydrocarbon presence.

sheen test

A visual check for free oil, made by observing whether a discharge leaves a visible film on the water surface.

shelf

The shallow, gently sloping submerged margin of a continent, from the shoreline out to about 200 m where the slope begins.

shelf couplers

Devices located at the ends of a tank car and used to connect the car to other cars in a train.

shelf edge

The break between shelf and slope.

shelf margin

The break where the gentle shelf steepens to the slope, and a persistent site of sand deposition.

shelf sand

Sand deposited on the continental shelf.

shell

The part of a fire tube boiler that holds the water necessary to produce steam.

shell and tube heat exchanger

A heat exchanger that consists of a shell, tubes, tube sheets, and heads that function together in the heat exchange process between two fluids.

shell side

The area within the shell and outside pf the tubes of a shell and tube heat exchanger.

shell-side fluid

The fluid flowing through the shell and around the outside of the tubes in a shell and tube heat exchanger.

shielded metal arc welding

A method of arc welding that uses short, coated electrodes to provide metal for the weld and material to create the gas shield. Also called stick welding.

shifted spectrum

An NMR technique comparing T2 distributions acquired at different echo spacings, so diffusion effects shift the spectra apart.

shifting tool

A slickline tool that engages a sliding sleeve's inner sleeve and moves it to open or close the ports.

shim

A thin plate inserted to adjust height or alignment.

ship dimension

The length, beam and draft that determine which ports and canals a vessel can use.

shipbroker

The intermediary who matches cargoes to ships and negotiates the charter.

shipowner

The party owning the vessel and supplying crew and maintenance under the charter.

shipping papers

Documentation that must accompany a hazardous materials shipment; shipping papers (sometimes referred to as manifests, invoices, or bills of lading) detail the type of hazardous material being shipped and any safety concerns presented by that material.

shoal

A shallow bank, on carbonate platforms a site of clean grainstone deposition.

shock

A condition caused by a sudden change in operating conditions that tends to severely disrupt a biological treatment process.

shoe

The fitting made up on the bottom joint of a casing string, and by extension the depth at which that casing ends.

shoe joint

The casing between the float shoe and the float collar, deliberately left full of cement.

shoe track

The joint or two of casing between the float collar and the shoe, deliberately left full of cement.

shoot a level

To fire an acoustic pulse down the annulus and time its echo, to find the liquid level in the well.

shoot a well

To acquire a check-shot or velocity survey by firing a surface source and recording at known depths in the well.

shooters

A shooter is a position on the field seismic crew whose primary responsibility is to detonate explosive charges, in coordination with the Observer.

shoreface

The zone from beach to shelf, whose upward-coarsening sand is a classic reservoir.

short

A condition of maximum current flow and minimum resistance in an electrical circuit; an accidental low-resistance current path.

short circuit

A connection accidentally established in an electrical circuit when an unintended path of very low resistance is created, causing current to reach its maximum value.

short position

Having sold more than is held, so gaining when prices fall.

short trip

Pulling the string only part way out of the hole and running it back, to check hole condition before committing to a full trip.

short- vs. long-term goals

Objectives for the coming months against those for the coming years.

short-circuit output current

The maximum continuous output current available from the amplifier with the output shorted to ground, to either supply, or to a specified point. Sometimes a low value series resistor is specified.

short-path multiple

A multiple that arrives within the duration of its own primary, typically 50 to 100 ms behind it.

short-term exposure limit (STEL)

The maximum amount of a substance to which a worker can be exposed for up to fifteen minutes.

shorting

Making an unintended low-resistance connection.

shot depth

The depth below surface or below sea level at which a seismic source is fired.

shot detection

Surface monitoring that confirms perforating guns have fired.

shot point

A surveyed surface location at which the seismic source is activated.

shothole

The drilled hole a land seismic charge is placed in.

shotholes

The shallow holes drilled to place explosive charges for land seismic.

should-cost modelling

Building an independent estimate of what a scope ought to cost, to test the bids received.

shoulder bed

The formation immediately above or below the bed a logging tool is reading.

shoulder tendinitis

Inflammation of the tendons of the shoulder. Also called rotator cuff syndrome, it can result from working overhead with heavy objects.

show

A show is a surface observation of hydrocarbons, which usually appears as florescent liquid on cuttings when viewed with an ultraviolet or black light (oil show) or increased gas readings from the mud logger's gas-detection equipment (gas show).

shrimp test

A bioassay using a living organism, typically mysid shrimp, to measure the toxicity of a fluid to be discharged.

shrink

A temporary drop in boiler drum level caused by changes in steam flow.

shrinkage

The volume reduction when reservoir oil loses its dissolved gas at surface.

shrinkage factor

The ratio converting reservoir volume to the smaller volume measured at surface.

SHRM

The Society for Human Resource Management, which awards its own competency-based HR credentials.

shroud

A metal plate or covering over the vanes of an impeller or over a compressor component, providing support and protection.

shunt

A DC motor in which the armature windings and the field windings are wired in parallel and energized by the same source.

shunt field

A machine field winding connected across the supply rather than in series with the load.

shunt motor

A DC motor in which the field coils and the armature are connected in parallel.

shunt reactor

Equipment used to improve power factor by offsetting excessive demand for capacitive power.

shunt regulator

A regulator that is in parallel with the load.

shunt resistor

The component in an ammeter that causes most of the current being measured to bypass the display circuitry; also called a meter shunt.

shut in

To close off a well so that it stops producing.

shut-in bottomhole pressure

The pressure measured at the bottom of a well after it has been closed in and allowed to stabilize.

shut-in pressure

The pressure measured at surface once the well is closed at the tree or the BOP stack.

shut-in royalty

A payment made to royalty owners to keep a lease alive when a capable well is shut in for want of a market.

shutdown procedure

The ordered method for taking equipment out of service safely.

shutdown system

The instrumented arrangement bringing a facility to a safe state on demand or on fault.

shutoff

Stopping flow completely, which a throttling valve is not designed to do.

shutoff valve

A valve intended only to be fully open or fully closed, not to throttle flow.

shutter ridges

A ridge which has moved along a fault line, blocking or diverting drainage.

SIBHP

Shut-in bottomhole pressure — the pressure at the bottom of the well once it has been closed in and stabilized.

SIBP

Shut-in bottomhole pressure, an alternative abbreviation for SIBHP.

side door overshot

The side door overshot is a fishing tool that is used to retrieve logging sondes that are stuck in a borehole. The advantage of this method is that it does not require the wireline to be cut. This tool is attached to drill pipe and lowered downhole.

side letter

A separate agreement modifying or interpreting the main contract, sometimes not disclosed to all parties.

side pocket mandrel

A tubing component with an offset pocket that holds a gas lift valve or other device clear of the main bore.

side-scan sonar

A towed acoustic system that images the seabed to either side of the tow path.

sidelobes

Sidelobes are additional components of the main source signature pulse that are usually noise and detract from the main signal.

sidereal

Sidereal: The time it takes for the Earth to complete one rotation about its axis, with respect to the “fixed” stars.

siderite

Iron carbonate, FeCO3, a dense diagenetic mineral of specific gravity about 3.8.

sidestream stripper

A small tower, with trays inside, that uses steam to remove light ends from the LCD fraction from the main fractionator.

sideswipe

An event on a 2D section reflected from a feature out of the plane of the line.

sidetrack

A secondary wellbore that deviates from the original wellbore. Intentional sidetracks might bypass an unusable section of the original wellbore or explore a nearby geological feature.

sidewall

Pertaining to something held against, or taken from, the wall of the borehole.

sidewall core

A small rock sample taken from the borehole wall by a wireline tool after the hole is drilled.

sidewall core (percussion sidewall core and rotary sidewall core)

A sidewall core is taken from the side of the borehole, using either percussion or a mechanical drilling process (rotary sidewall cores).

sidewall core (percussion sidewall cores and rotary sidewall cores)

A core taken from the side of the borehole using either a percussion tool (firing hollow bullets) or a mechanical drilling process (rotary sidewall cores).

sidewall core acquisition

Taking small samples from the borehole wall after drilling.

sidewall core sample

A small sample taken from the borehole wall.

sidewall cores

A sidewall core is a small cylindrical core of rock, of maximum length 3 in. and maximum diameter 1 in., taken from the side of the open borehole using a logging tool run on wireline. Sidewall cores can be acquired using either percussion or mechanical drilling methods.

sidewall coring

Taking small samples from the borehole wall with a wireline tool, when no core was cut.

sidewall coring tool

The device recovering samples from the borehole wall.

siemen

Standard international unit of measurement for conductivity. Usually expressed in readouts as micro siemens, S.

Sierpinski gasket

A fractal built by repeatedly removing the central triangle from each remaining triangle.

sieve

A screen of known aperture used to separate a sample into size fractions.

sieve analysis

The measurement of a sand or gravel's grain size distribution by passing it through a stack of graded screens.

sight glass

A device located on the outside of a vessel or separator used for monitoring and checking liquid levels inside.

sight glass valve

The isolation valve on a sight glass, closed before the glass is cleaned or replaced.

sightglass

A transparent vertical tube attached to a tank that fills to the same level as the liquid in the tank, allowing operators to see the level in the tank.

sigma

Sigma is the macroscopic cross section for the absorption of thermal neutrons, or capture cross section, of a volume of matter, measured in capture units.

signal

Electronic information sent from one device or element to another.

signal common

Similar to electrical ground. In op amp circuits with bipolar supply voltages. signal common is a point that is electrically common to the supply voltages and to the input and output voltages; usually zero volts.

signal-to-noise ratio

The ratio of wanted energy to unwanted energy in a recording.

signature

The waveform a seismic source actually produces, in shape, amplitude, polarity and phase.

signature bonus

Cash consideration paid to a landowner or mineral owner upon the execution of an oil and gas Exploration Agreement.

signature deconvolution

A processing step that uses the recorded source waveform to replace it with a shorter, known wavelet.

signed number

A number that is marked as either positive or negative.

silica

Silicon dioxide, SiO2, occurring as crystalline quartz, cryptocrystalline chert and amorphous opal.

silica gel

A porous solid desiccant adsorbing water, used to dry gas and instruments.

silica layer

The sheet of linked silica tetrahedra that forms one of the two building layers of a clay mineral.

silicate

A compound containing silicon and oxygen combined with metal cations.

silicate anion

The SiO4 4- ion present in sodium and potassium silicate solutions, formed by dissolving silica in caustic.

silicate mineral

A rock-forming mineral built from SiO4 tetrahedra linked to each other and to cations.

silicate mud

A water-base mud inhibited with sodium or potassium silicate, which gels in the pore mouths of an exposed shale and seals it.

silicates, silica

A silicate is a compound containing an anionic silicon compound. The great majority of silicates are oxides.

silicic acid

The acid form of dissolved silica, which polymerizes through Si-O-Si bonds as pH falls.

siliciclastic

Siliciclastic is containing silica.

siliciclastic sediment

Siliciclastic sediments are silica-based, non-carbonaceous sediments that are broken from pre-existing rocks, transported elsewhere, and redeposited before forming another rock.

silicon controlled rectifier (SCR)

A unidirectional electronic device that has three P-N junctions. The point at which the device can conduct can be controlled by applying a potential to its gate. SCR's are often used as rectifiers when the value of DC output must be regulated.

sill

A sheet of igneous rock injected parallel to bedding, which can seal or destroy a reservoir.

silo

A relatively large and narrow, vertical, cylindrical vessel that usually has a closed, dome-shaped top.

silt

Particles between 2 and 74 micrometres across — finer than sand and coarser than clay.

siltstone

A sedimentary rock with a grain size in the silt range, finer than sandstone and coarser than claystone.

siltstone, silt

A sedimentary rock with a grain size in the silt range, finer than sandstone and coarser than claystone.

siltstone, silt, silty

Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystone.

silver nitrate

The titrant used to measure chloride content, with potassium chromate as the endpoint indicator.

silver oxide

A film that forms on the surfaces of silver contacts; a good conductor of electricity.

similar fold

A fold whose layers keep constant thickness measured parallel to the axial surface, so each layer repeats the same shape.

simple and compound interest

Interest on the principal only, against interest that itself earns interest.

simple multiple

A multiple involving one deep reflector and one near-surface reflector such as the sea floor or the base of weathering.

simplex

Optical cable containing one fiber.

simplex piston pump

A piston pump that contains one piston.

simplex pump

A reciprocating pump that contains a single piston, plunger, or similar device.

simplification

Reducing a model to its essential elements so it can be solved or understood.

simulated annealing

An optimization method that accepts worse solutions early and fewer later, by analogy with cooling a metal into a low-energy state.

simulation

A modeled environment where a learner practices without real consequence.

simulation [evidence]

The employee performs a task in a simulated or training environment. Simulation is used when the employee is unlikely, within a reasonable time frame, to have the opportunity to demonstrate competence at the workplace. Any simulation will have to mirror real activities and must be stated in the assessment plan.

simulation [learning resource]

Simulation-based training uses simulated environments and scenarios to prepare learners for real-life situations. The learner can practice in a safe, controlled setting before facing actual challenges in the workplace. They are more motivated and engaged, leading to better long-term retention of skill and knowledge.

simulation model

The gridded numerical model used to forecast reservoir performance.

simulation study

A modeling exercise run to compare development options before capital is committed.

simultaneous operation (SIMOP)

Two or more activities carried out at the same time on one installation, where each could affect the safety of the other, abbreviated SIMOP.

sinc x

The function sin(x)/x, the shape that a perfect band-limiting filter takes in the time domain.

sine curve

A sine curve is a curve representing periodic oscillations of constant amplitude as given by a sine function.

sine wave

The output voltage waveform produced by a typical AC generator.

single

A single is one section of drill pipe, 30 ft (9.1m) in length.

single blade damper

A type of damper that has only one blade. Also known as a butterfly damper.

single customer view

One consolidated record of a customer across every channel and system.

single hull

The older tanker design without an inner hull, now largely phased out.

single line diagram

A drawing that shows all of the circuits of a system as single lines.

single loop

A closed process control loop in which a single process variable is controlled by a single analog or digital controller.

single loop control

A type of process control in which one process loop is controlled by a single controller.

single phase

Consisting of only one fluid phase — all liquid or all gas.

single phasing

The loss of voltage on one of three phases of a three-phase circuit.

single shot

A signal measured by an oscilloscope that occurs only once.

single sweep

A trigger mode for displaying one screen full of a signal and then stopping.

single-acting compressor

A compressor which compresses gas on only the forward stroke.

single-acting pump

A reciprocating pump that operates by admitting fluid on one part of the reciprocating movement and discharging fluid on the other part.

single-azimuth towed-streamer acquisition

Conventional marine acquisition with one vessel towing sources and streamers along straight parallel lines in a single direction.

single-barrel, offset tongue connector

A mechanical connector that is used for terminating a single conductor. The offset tongue allows the terminal and the conductor to he relatively flat against a surface.

single-conductor cable

A cable that consists of one large stranded conductor.

single-duct ventilation system

A system that has one supply air duct and one return air duct.

single-leg sling

A length of wire rope, chain, or synthetic material with some type of fitting or connector at each end.

single-mode fiber

Fibers with a central core of about 9 microns. Commonly used either for very high data transmission speed or long distance Wide Area Networks.

single-pass condenser

A type of condenser in which circulating water flows through the condenser only once.

single-pass heat exchanger

A heat exchanger in which each fluid passes through only once.

single-pass method

Interpreting a spinner flowmeter from one logging run, using a calibration taken from elsewhere.

single-phase flow

Flow in which only one fluid phase is present.

single-phase generator

A generator that has one stator winding and produces one output voltage.

single-point level detection

A system of level measurement that monitors levels at critical points; when a liquid reaches a predetermined level, the system initiates an alarm or a corrective action.

single-shot reclosing

A reclosing relay that recloses a circuit breaker only once, usually instantaneously.

single-shot survey

A directional survey taking one measurement of inclination and azimuth at a single depth.

single-stage compressor

Compressor achieving its whole ratio in one stage, simple but limited by discharge temperature.

single-strand conductor

A conductor that consists of a single wire.

single-tank composite sample

A blend of samples drawn from the top, middle and bottom of one storage tank.

sinistral

Said of a strike-slip fault on which the far block has moved to the left as seen by an observer facing it.

sinker bar

A weight bar run at the top of a slickline toolstring to push the string down against wellhead pressure and stuffing box friction.

sinking

An electrical connection with the field device connected to the power source. In sinking I/O modules, the common side connects to ground and the field device connects to the power source and the module.

sinking connection

A type of electrical connection. Sinking input or output modules have their common side connected to ground. The field device has one side connected to the power source and the other to the I/O module's terminal.

sintered

Made by fusing small particles together with heat and pressure without fully melting them.

sinusoid

Another term for a sine curve.

sinusoidal

Following a sine curve, the shape a dipping bed makes on a borehole image.

sinusoidal oscillator

An oscillator that produces a sine wave signal.

siphon

A flow arrangement using gravity and pressure difference to move liquid over a rise.

siphon system

An arrangement drawing liquid over a rise by pressure difference rather than by pumping.

SIPOC diagram

A high-level map of suppliers, inputs, process, outputs and customers.

sites

Charged locations on resin beads that attract and hold ions.

siting

Choosing where a facility goes, weighing resource, grid access, permits and public acceptance.

situational awareness

Knowing what is happening around you and what it implies, whose loss precedes many incidents.

Six Sigma

A method of reducing process variation until defects become statistically rare.

Six Sigma Green Belt certification

Recognition of ability to lead a defined improvement project.

Six Sigma Yellow Belt certification

Recognition of ability to contribute to an improvement team.

Six Thinking Hats

De Bono's method of examining a decision from one defined perspective at a time.

six-step model for difficult conversations

A structure for raising a hard subject that keeps the discussion on behavior and outcome.

sixteen-bit word

A digital expression of 16 bits; for example, 0100 0111 0100 0111.

sized calcium carbonate

Ground limestone, marble or shell supplied to a controlled particle size range for bridging.

sized salt

Sodium chloride ground to a controlled particle size distribution, used as a bridging and lost circulation material.

sizer

A device used to determine the proper size of respirator for an individual to wear.

skewness

A measure of how asymmetric a distribution is about its mean.

skid

A steel frame carrying a machine and its auxiliaries as a single unit, so it can be lifted and moved intact.

skill gap

The distance between current ability and the standard the role requires.

skill gap assessment

Comparing current capability against what the plan requires, to size the development need.

skill gap matrix

The grid of people against competencies that makes coverage and single points of failure visible.

skill-based information

Information that requires hands-on experience to practice and learn; usually taught more effectively through OJT than in a classroom.

skilled application (competency level 3)

Able to analyze and explain task in depth including impact on operations, key operating parameters and other related systems & processes / Able to troubleshoot / Can identify abnormal situations / Able to work independently / Applies procedures consistently and understands concepts / Shares and transfers information, best practices, and lessons learned / Mentors and coaches less experienced employees.

skills-based information

Information that requires hands-on experience to practice and learn; usually taught more effectively through OJT than in a classroom.

skimmer

A device removing a floating layer from a liquid surface.

skin

A dimensionless number expressing the extra pressure drop near the wellbore caused by damage or by stimulation.

skin damage, factor

The most commonly used measure of formation damage in a well is the skin factor, S. The skin factor is a dimensionless pressure drop caused by a flow restriction in the near-wellbore region.

skin depth

The depth at which an electromagnetic field has fallen to 1/e of its surface amplitude in a conductive medium.

skin effect

The loss of amplitude and shift in phase suffered by an electromagnetic field as it penetrates a conductor.

skin factor

A dimensionless number representing the degree of formation damage caused by drilling.

skin factor, skin

The skin factor (s) is a dimensionless number representing the degree of formation “damage”, or “improvement”, each of which can be the result of a number of different causes. Formation damage is assigned a positive number; formation improvement is assigned a negative number.

slack water

A short period in a body of tidal water when the water is completely unstressed and there is no movement either way in the tidal stream. This period occurs before the direction of the tidal stream reverses.

slaked lime

Calcium hydroxide, Ca(OH)2, made by adding water to quicklime.

slam retarder

A damper that slows a check valve's clapper as it closes, so it seats without shock.

slant rig

A rig whose mast and drive are inclined, so the well starts deviated from surface rather than kicking off below it.

slant stack

A transform that sums traces along straight lines of varying slope, mapping the gather into intercept time and ray parameter.

slant-hole rig

A rig whose mast and drive are inclined, so the well starts deviated at surface instead of being kicked off below it.

sleep hygiene

The habits that determine sleep quality, and through it daytime performance and safety.

sleeve bearing

A plain bearing in which the shaft turns on a lubricated cylindrical surface.

slew rate

The rate of change in the output voltage with respect to time for a step change at the input.

slickensides

Smoothly polished rock surfaces caused by frictional movement between rocks along both sides of a fault or fracture.

slickline

A thin, non-electric cable used for the selective placement and retrieval of wellbore hardware, such as plugs, gauges, and valves located in sidepocket mandrels.

slickwater

A low-viscosity fracturing fluid using friction reducer instead of gel.

slide

To drill with a mud motor turning the bit while the drillstring is held without rotating, so the bent housing steers the hole.

slide readability

Whether the slide can actually be read from the back of the room.

sliding scale

A term that varies with production rate, profitability or cumulative return rather than staying fixed.

sliding sleeve

A tubing-mounted device with ports that can be opened or closed downhole to connect the tubing to the annulus.

sliding surface bearing

A bearing carrying load on a lubricated sliding film rather than on rolling elements.

sliding vane

A vane sliding in a rotor slot to sweep the working volume.

sliding vane pump

A rotary pump that uses vanes that slide in and out of a rotor to move fluid.

slightly compressible

Changing volume only a little with pressure, the usual assumption for liquids.

slightly dolomitic limestone

Limestone with a minor dolomite component, which alters its porosity and acid response.

slim-tube test

A laboratory displacement through a long sand-packed tube, run at several pressures to find the minimum miscibility pressure.

slime-forming bacteria

Bacteria that grow as dense surface mats, tolerating either the presence or the absence of oxygen.

slimhole

An inexact term describing a borehole, and its associated casing program, that is significantly smaller than a standard approach, commonly a wellbore with a diameter less than 6 inches.

slimhole logging tool

A slimhole logging tool is one capable of being run in small borehole diameters, sometimes as small as 3 7/8 inches in diameter.

slimhole well

A well drilled and cased significantly smaller than conventional, often with a final hole under 6 inches.

sling

A length of wire rope, chain, or synthetic material used to secure a lifting device to a load, often serving as the connecting link between them.

sling angle

The angle a sling makes with vertical, which multiplies the tension it carries.

sling psychrometer

A device that is commonly used for spot-checking humidity measurements.

slip

The difference in speed between the stator's magnetic field and the rotor in an AC motor, often expressed as a percentage.

slip and cut

To move the drilling line through the system and cut off the worn section, so wear is redistributed and the line renewed.

slip blind

A circular metal plate installed in a line to prohibit flow. Normally the blind has a "Tee" handle to facilitate the identification, installation, and removal of the blind.

slip joint

A telescoping joint that lets a string change length while its two ends stay connected.

slip lock

A slickline-set lock that anchors on the tubing wall with slips rather than in a machined nipple profile.

slip rings

Metallic rings used on some AC generators either to transfer the output voltage to brushes that are connected to an external circuit or to carry excitation current from the exciter to the field of the AC generator.

slip velocity

The difference in velocity between two phases, or between a particle and the fluid carrying it.

slip-on flange

A flange with a socket-type hub that slips over the end of a piece of pipe and is welded to the pipe.

slip-type micrometer

An outside micrometer with a slip device to keep excess pressure from being applied from the tool to the object being measured.

slippage

The difference between the theoretical and actual displacement of a pump or a fluid.

slips

Wedge-shaped gripping segments that hold a tubular by friction against a tapered bowl.

slop drain

The drain from the area that collects leakoff from a pump's stuffing box.

slop tank

See Recovery tank.

slope

On a graph or an oscilloscope screen, the ratio of a vertical distance to a horizontal distance.

slotted liner

A liner with cut slots, holding the hole open while letting fluid in without gravel or screens.

slotted liners

Slotted (or pre-perforated) liner completions are by far the most common completion run in horizontal wells. The primary purpose of the slotted liner is preventing hole collapse in formations that may tend to cave in after being drilled, or as the formation pressure depletes.

sloughing

Wellbore wall material falling in, usually from unstable shale.

sloughing shale

Shale that breaks away from the borehole wall and falls into the hole, producing cavings and pack-off risk.

slow formation

A formation whose shear velocity is below the compressional velocity of the borehole fluid.

slow-release inhibitor

A corrosion inhibitor formulated or packaged to dissolve gradually into the produced stream over weeks or months.

slowing-down length

The average distance a fast neutron travels while being moderated down to epithermal energy.

slowing-down time

The characteristic time for fast neutrons to be moderated to epithermal energy, measured by an epithermal neutron tool.

slowness

Slowness is the reciprocal of velocity.

slowness time coherence

A processing method that searches an array of sonic waveforms for the slowness and arrival time at which the energy is most coherent, abbreviated STC.

sludge

Suspended solids that have settled and formed a thick mixture; a thick concentration of suspended solids in cooling towers, wastewater, or other systems.

sludge blanket

The suspended layer of settled solids in a clarifier, through which incoming water is filtered.

sludge blanket level

The height of the settled solids layer in a clarifier.

sludge handling

Treating sludge to reduce its volume and prepare it for safe disposal.

slug

A small volume of heavy mud pumped into the drillpipe before a trip so the pipe stands dry when it is pulled.

slug flow

A two-phase flow regime in which liquid plugs and large gas pockets pass alternately along the pipe.

slugging

The intermittent arrival of liquid slugs at the end of a multiphase line, driven by terrain or by flow instability.

slugging compound

A demulsifier added to a crude sample so the water separates and the sediment and water content can be read.

slugging pill

A small volume of mud weighted above the system, pumped into the drillpipe so the string can be pulled dry.

slumping

A condition in which a loss of aeration causes the catalyst to become less fluid and back up in a cat cracker.

slurries

Plural of slurry, a suspension of solid particles in a liquid.

slurry

A mixture of liquid and solids flowing together.

slurry density

The mass per unit volume of a slurry, in lbm/gal or kg/m3.

slurry service

Duty in which the fluid handled carries suspended solids.

slurry stability

A cement slurry's resistance to settling of solids and separation of free water while it is still fluid.

slurry yield

The volume of slurry produced from one sack of cement with its water and additives, in cubic feet per sack.

small business management

Running a business where the owner is close to every function.

small volume prover

A precise volume checking device which can prove flow meters with fewer pulses.

small-pore water

Water held in micropores and pore corners, immobile under normal production drawdown.

smart analog

An analog instrument with digital processing and communication added.

smart controller

A controller with its own processor, able to self-diagnose and communicate digitally.

smart device

A process control field device with an internal microprocessor that can store data, instructions. etc. A fully digital device can transmit process data to and receive configuration data from controllers or a DCS.

SMART goal action plan

The steps, owners and dates that turn a stated goal into work.

SMART goals

Goals framed as specific, measurable, achievable, relevant and time-bound.

smart pigging

Smart or “intelligent” pigs inspect the pipeline with sensors and record the data for later analysis.

smart transmitter

A transmitter with its own processor, able to self-diagnose and be configured remotely.

smectite

A group of clay phyllosilicate minerals with a relatively open, three-layer 2:1 (TOT) structure, including dioctahedral smectites (such as montmorillonite and nontronite) and trioctahedral smectites (such as saponite). They mainly consist of montmorillonite but can contain secondary minerals such as quartz and calcite.

smectite clay

A three-layer clay group, one alumina sheet between two silica sheets, that swells when it takes water into its interlayer.

smile

A concave-upward arc on a migrated section, produced by migrating noise or by using too high a velocity.

smoke point

The flame height a kerosene reaches before smoking, a proxy for aromatic content in jet fuel.

smolen

The author of a widely used cased hole log interpretation text.

Snell's law

The relation fixing the angle at which a wave refracts crossing into a medium of different velocity, the ratio of the sines equalling the ratio of velocities.

SNG

Synthetic natural gas — methane-rich gas manufactured from coal or heavy hydrocarbons rather than produced.

snowballing

A condition in which coke deposits on the catalyst build up on previous deposits; caused by insufficient combustion.

snub

To force pipe into a live well against wellbore pressure, with the preventers closed.

snubbers

The opposed sets of slips on a snubbing unit that grip the pipe and control it against well pressure.

snubbing

Running or pulling pipe in a well that is under enough pressure to eject it, using a hydraulic unit to hold it against that force.

snubbing basket

The elevated work platform on a snubbing unit, carrying the operator's controls and the tubular handling equipment.

snubbing force

The push needed to drive a string into a live well against the pressure acting to expel it.

snubbing jack

The hydraulic cylinders of a snubbing unit that provide the stroke to push or pull the work string against well pressure.

soak

The time specified to keep a process variable at a designated set point during a ramp startup.

soak phase

The shut-in period in cyclic steam injection, between injecting steam and putting the well back on production.

soap

The salt formed when a fatty acid reacts with a base, and a surface-active agent as a result.

social circles of influence

The rings of relationship through which opinion actually travels in a community.

social licence renewal

Re-earning community acceptance, which lapses if the relationship is not maintained.

social license to operate

The acceptance from communities and society that lets a project proceed, which no permit confers.

social life cycle analysis (S-LCA)

A methodology for assessing internalities and externalities of the production of goods and services based on social and socioeconomic indicators.

social media influencer

Someone whose following makes their endorsement commercially valuable.

social media marketing

Using social platforms to reach and engage an audience.

social motives

The underlying drives — achievement, affiliation, power — that shape how a person leads.

sock filter

A replaceable fabric filter element shaped like a sock.

socket

A type of end fitting that is used to attach a wire rope to other rigging equipment.

socratic method

Questioning assumptions systematically to expose what an argument actually rests on.

soda ash

Sodium carbonate, Na2CO3, used to precipitate calcium out of a water-base mud.

sodium acid pyrophosphate

A phosphate used to treat cement contamination and to thin low-temperature water muds, abbreviated SAPP.

sodium bicarbonate

NaHCO3, used in a water-base mud to remove calcium introduced by cement or gypsum contamination.

sodium carbonate

Na2CO3, also called soda ash or washing soda, a white hygroscopic alkaline powder.

sodium chloride

Common salt, present in formation water and used to weight and inhibit drilling fluids.

sodium chloride (NaCl) equivalent

The sodium chloride (NaCl) equivalent is correctly calculated using the following formula: Sodium (mg) \( \small \times \) 2.54 ÷ 1,000 = Salt content (g).

sodium chromate

Na2CrO4, a hexavalent chromium salt formerly used as a corrosion inhibitor and mud thinner.

sodium dichromate

Na2Cr2O7, a strong oxidiser used with zinc sulfate as a corrosion inhibitor in drilling fluids.

sodium hydroxide

NaOH, called caustic soda, the standard alkali for raising the pH of a water-base mud.

sodium hydroxide (NaOH)

A dilute alkali solution that s used to treat products that contain relatively small amount of H₂S: Also known as caustic soda.

sodium ion

The sodium cation, exchanged for hardness ions in a softener.

sodium phosphate

A sodium salt of phosphoric acid, used in muds as a thinner and to precipitate calcium contamination.

sodium polyacrylate

The sodium salt of polyacrylic acid, an anionic polymer used as a mud deflocculant and fluid-loss additive.

sodium silicate

An alkaline silicate solution made by dissolving silica in caustic soda.

soft rock

Informal term for sedimentary rocks and the petroleum geology practiced on them, as opposed to hard rock mining geology.

soft solder

A fusible alloy that consists primarily of tin and lead.

soft vs. hard metrics

Perception measures against countable ones, both needed to see whether inclusion is real.

soft water

Water low in calcium, magnesium and iron, and so suitable for prehydrating bentonite and polymers.

softener

The ion exchange unit removing hardness from water.

softline

Rig slang for non-steel rope — manila, nylon or cotton.

software

Programs composed of coded instructions that determine the functions of a computer, including screen display, operating environment, and various specific tasks such as word processing, database management, etc.

software as a service (saas)

Software delivered over the internet on subscription, with the provider running the infrastructure, abbreviated SaaS.

software development life cycle (SDLC)

The stages from requirements through design, build and test to maintenance.

solar photovoltaic

Generation converting sunlight to electricity in semiconductor cells, as distinct from solar thermal.

solar terrestrial rhythms

The regular periodicities in Earth's orbit and climate driven by its relationship with the sun.

solder connectors

Connectors that require soldering when they are insulted.

soldering

A welding application that uses lead-tin or silver solder as a filler and bonding material.

solderless connectors

Connectors that do not require soldering when they are installed. They include compression connectors and mechanical connectors.

sole proprietorship

A business owned by one person with no legal separation from them.

sole risk

A mechanism letting willing partners proceed alone when others decline, at their own cost and reward.

sole risk assets

Assets one partner develops and funds alone after the others decline to participate.

sole risk operation

Work undertaken by willing partners alone when others decline to participate.

solenoid

An on/off type of electric device, usually a coil of conducting wire, that uses an electromagnetic field to move metallic objects or operate valves. Also called a solenoid actuator.

solenoid actuator

An actuator moved by an electromagnet, usually two-position.

solid bed leaching

A leaching system in which a sol vent flows through a fixed bed of solid particles.

solid debris

Loose solids in a stream, which erode, plug and foul.

solid desiccant

A porous solid such as silica gel, activated alumina or a molecular sieve, used to adsorb water from a gas stream.

solid oxide

A ceramic electrolyte conducting oxygen ions at high temperature, used in both fuel cells and electrolyzers.

solid particle

A discrete solid carried in a fluid.

solid proppant

The granular material holding a fracture open after pressure is released.

solid-state circuit element

A relay element in which inputs are electronically processed through circuits to produce an output signal.

solid-state relay

A relay that consists of electronic circuits instead of moving electrical and mechanical parts.

solubility

How much of a substance a solvent can hold before the solution saturates, quoted at a stated temperature and pressure.

solute

The substance that is dissolved in a solution.

solution

In chemistry, one or more substances evenly dispersed throughout another substance (a homogeneous mixture) not easily separated by mechanical means. In geology, refers to the process where substances (such as carbonate sediments) form out of or dissolve into liquid, typically a brine solution, playing a crucial role in sediment transport and deposition.

solution evaluation

Assessing whether a delivered solution actually produced the intended benefit.

solution gas

Natural gas that is dissolved in crude oil in the reservoir at prevailing reservoir conditions of temperature and pressure. Also called entrained gas.

solution gasdrive

A drive mechanism in which gas coming out of solution as pressure falls expands and pushes the oil to the wells.

solution voids

Solution voids are spaces within a rock where some rock material has dissolved.

solvent

A substance that can dissolve another substance; usually the component making up the greater amount of a solution. Also, an ingredient added to a mixture to reduce attraction between molecules of close-boiling components and increase the difference in their volatilities.

solvent flow

The solvent circulation rate through an absorber or extractor.

solvent flow rate

The solvent circulation rate through an absorber or extractor.

solvent recovery

Recovering solvent from a stream so it can be reused rather than lost.

solvent recovery column

The column recovering solvent for reuse.

sonde

The part of a logging tool carrying the sensors, as distinct from the cartridge that holds the electronics.

sonde error

The nonzero reading an induction tool gives in a medium of zero conductivity, subtracted as a baseline correction.

sonde, logging sonde

The section of a logging tool that contains the measurement sensors, distinct from the cartridge that contains the electronics and power supplies.

sonic

Sonic, alternatively termed acoustic, is the branch of physics concerned with the properties of sound.

sonic log

A log of the time a compressional wave takes to travel a fixed distance through the formation, recorded as slowness against depth.

sonic log, acoustic log

A display of the travel time of acoustic (compressional) waves versus depth in a well. Sonic tools emit a sound wave that travels from the source to the formation and back to a receiver.

sonic logging

Measuring the formation's acoustic travel time, from which porosity and elastic properties follow.

sonic measurement

The determination of formation slowness from the transit time of an acoustic pulse between transmitter and receiver.

sonic monopole transducers

Sonic monopole (axisymmetric) transducers generate omnidirectional sonic, or acoustic, waves.

sonic tool

A logging tool measuring the formation's acoustic travel time.

sonic velocity, acoustic velocity

Sonic, or acoustic velocity, is the velocity of a sonic, or acoustic, wave in a medium.

sonolog

An acoustic survey that locates the annular fluid level from the echo time of a shot fired at the wellhead.

sootblower

A device that uses steam or compressed air to blow ash or slag off boiler tubes.

sootblowing

A method of controlling steam temperature by using sootblowers to remove soot from boiler tubes.

sorbed gas

Gas accumulated on the surface of a grain of reservoir rock or organic particles in a shale reservoir.

sorting

The range of sedimentary grain sizes that occur in sediment or sedimentary rocks.

sound

Any pressure variation that the human ear can detect.

sound waves

A series of pressure vibrations that travel through a medium such as air or water.

sour

Containing hydrogen sulfide or other sulfur compounds in commercially or operationally significant amounts.

sour corrosion

Corrosion of steel by hydrogen sulfide dissolved in water, producing iron sulfide and atomic hydrogen.

sour crude

Generally, a crude oil whose sulfur content is greater than 1%.

sour crude oil

Crude containing hydrogen sulfide, mercaptans or carbon dioxide above the sweet specification.

sour gas

Natural gas containing significant amounts of acid gases (hydrogen sulfide and/or carbon dioxide).

sour gas stream

Gas carrying hydrogen sulfide or carbon dioxide, requiring treatment before sale.

source

The primary source that provides the power that is converted to electricity through chemical, mechanical, or other means. Energy sources include coal, petroleum and petroleum products, gas, water, uranium, wind, sunlight, geothermal, and other sources.

source array

A group of sources fired together to shape the wavefield and cancel unwanted energy.

source conversion

The proportion of candidates from each channel that reach hire, showing which channels work.

source interval

The spacing between source points along a line.

source pattern

An arrangement of several seismic sources fired together or in sequence, acting as one effective source.

source point

A surveyed location at which the seismic source is fired.

source rock

Source rock is a rock capable of generating petroleum. Source rocks are usually shales, sometimes limestones.

source sampling

The process of using manual measurement methods to determine the emissions from a potential air pollution source.

source static

The static correction belonging to a source position.

source unit (source)

In a nuclear radiation system for level measurement or control, the part that contains the radioactive source and shielding; mounted externally on a container.

source voltage

The voltage the supply provides.

source wavelet

The pulse the seismic source emits, which convolves with reflectivity to make the trace.

sources and cost of debt and equity

Where a project's funding comes from and what each component charges for it.

sources of power

Where influence comes from: position, expertise, information, relationship, reward, coercion.

sourcing

An electrical connection with the field device connected to ground/common. In sourcing I/O modules, the common side connects to the power source and the field device connects to ground/common and the module.

sourcing connection

A type of electrical connection. Sourcing input or output modules have their common side connected to the power source. The field device has one side connected to ground/common and the other to the I/O modules terminal.

sourcing strategy

The deliberate plan for where and how a category will be bought.

south pole

The southernmost point of the Earth's axis.

sovereign cloud

A cloud environment built so that all data and operations stay within one country's legal jurisdiction.

sovereign immunity

A state's protection from suit, which contracts waive so disputes can actually be arbitrated.

Soxhlet extractor

A glassware apparatus that repeatedly washes a sample with condensing solvent vapor to extract its hydrocarbons.

SP

Shotpoint — a surveyed surface location at which a seismic source is fired.

space frequency domain

The two-dimensional transform of seismic data into frequency against wavenumber, called the f-k domain.

space management

A defensive driving technique that involves always keeping an appropriate amount of space around a vehicle to the front, to the sides and to the rear. It also involves staying out of an area where you can be in an accident as a result of someone else's sudden move or mistake.

space out

To adjust the length of a string with pup joints so a component lands at the exact depth required.

spacer

A metal disk similar in appearance to a slip blind, except that the spacer is not solid and thus permits flow through the line.

spacer fluid

A fluid pumped between two others to keep them from mixing.

spacing

The distance between wells producing from the same reservoir. Spacing is often expressed in terms of acres (e.g. 80-acre spacing) and is often established by regulatory agencies.

spacing unit

The area of land assigned to one well by regulation or field rules, defining how closely wells may be drilled.

spade terminal

A crimp-on terminal that has a forked tongue. Also called a fork terminal.

span of control

How many people report to one manager, which limits how closely each can be supported.

sparker seismic surveys

A seismic survey in which the energy source is an electrical discharge. The discharge occurs between two electrodes that are submerged in salt water. The heat generated by the discharge vaporizes the water, which then condenses to create an implosion.

spatial aliasing

Distortion caused by sampling seismic too coarsely across space.

spatial resolution

The smallest separation a measurement can distinguish.

spatial sampling

How finely the wavefield is sampled in space, which sets what can be imaged without aliasing.

speaking anxiety

The physiological stress response before speaking, manageable rather than eliminable.

spec plate

A plate that lists a tank truck's design specifications and Department of Transportation (DOT) classification.

special core analysis

Special core analysis, often abbreviated to SCAL, is a laboratory procedure for conducting flow experiments on core plugs taken from a petroleum reservoir. Special core analysis is distinguished from "routine or conventional core analysis" by adding more experiments, including measurements of two phase flow properties, determining relative permeability and capillary pressure.

special core analysis (SCAL)

A set of laboratory procedures for conducting flow experiments on core plugs, distinguished from routine core analysis by adding measurements of two-phase flow properties, including determining relative permeability and capillary pressure.

specialized product

A refined product made for a particular application rather than for general sale.

specialty company

A firm making small-volume, high-value products rather than bulk commodities.

specialty product

A refined product made in small volume for a specific use, usually at higher margin.

specific gravity

The ratio of the weight (or density) of a fixed volume of a substance to the weight (or density) of an equal volume of water, indicating whether a liquid is more or less dense than water.

specific gravity test

A test that determines the density of a liquid compared to the density of water at a standard temperature.

specific permeability

The permeability of a rock measured with a single fluid completely filling the pore space, also called absolute permeability.

specific permeability, absolute permeability

The permeability when a single fluid, or phase, is present in the rock. Often referred to as absolute permeability.

specification sheet

The document stating the required properties of equipment or product.

specification sheets

Written requirements issued by architects and engineers to establish general conditions, standards, and detailed instructions to use with the blueprints; also referred to as specs.

specificity

Naming the particular rather than the general, which is what makes writing usable.

specified range

The band a device is guaranteed accurate over.

spectacle blind

A combination blind and spacer formed from the same piece of metal. A spectacle blind has the shape of a figure "8". One end is solid and prohibits flow when inserted in the line; the other end is open and permits flow when inserted in the line.

spectral

Pertaining to how a signal's amplitude and phase are distributed across frequency.

spectral density analysis

Analysis of how a log's variance is distributed across spatial frequencies, used to characterize the scaling behavior of reservoir heterogeneity.

spectral fitting analysis technique

In the spectral fitting analysis technique, the elemental signature of elements is matched for the entire spectra.

spectral gamma

Gamma logging separating potassium, thorium and uranium, which distinguishes clay type from mere shaliness.

spectral gamma ray

Spectral gamma ray logs measure the amounts of potassium, thorium and uranium naturally emitted by rocks, which offers several advantages. They can help with clay typing. Variations of the relative amounts of potassium, thorium, and uranium are associated with specific shale minerals.

spectrometer

An instrument separating a signal by wavelength or mass to identify composition.

spectrometry

Measuring the energy spectrum of radiation, used to identify elements in the formation.

spectrophotometer

An instrument measuring how much light of a chosen wavelength a sample absorbs.

spectroscopy

The study of the interaction between matter and radiated energy. Used in pulsed neutron logging to measure the spectrum of gamma rays emitted by a formation bombarded by high-energy neutrons. Also, an analytical technique based on the interaction of electromagnetic radiation with matter.

spectrum

The distribution of a signal's energy or amplitude across frequency.

speculator

A trader taking price risk deliberately rather than hedging an underlying exposure.

speed coupling

A coupling between shafts running at different speeds through a gear.

speed range

The relationship between the maximum and minimum speeds at which a drive is designed to operate. The range is typically expressed as a ratio, such as 25:1, indicating the drive can operate from normal speed to 1/25 of normal speed.

spent catalyst

Catalyst with coke deposits resulting from the cracking process.

sphere

A ball-shaped tank that rests on legs elevating it off the ground. A type of high-pressure above ground storage tank.

spherical divergence

The fall in wave amplitude with distance as a fixed amount of energy spreads over an expanding wavefront.

spherical flow

Flow converging on a point from all directions, as into a probe or a partially penetrating completion.

spherical flow regime

A spherical flow regime is a flow regime that occurs when the predominant flow pattern is toward a point.

spherical focusing

An electrode arrangement that holds the equipotential surfaces spherical around the current electrode, confining the measurement to a defined volume.

spherical harmonic

One of the set of functions that solve Laplace's equation in spherical coordinates, used to describe a global field.

spherical separator

A ball-shaped separator vessel, compact and cheap for its pressure rating.

spherical spreading

The fall in wave amplitude with distance as energy spreads over a growing surface.

spherical wave

A wave spreading outward equally in all directions from a point source.

spherically focused log

A shallow resistivity measurement focused to read the flushed zone.

spheroid

A flat-bottomed, pumpkin-shaped spherical pressure tank that rests on the ground or on a concrete pad, braced by a series of supports around the base. Generally used as a low-pressure tank.

SPHR (Senior Professional in Human Resources)

The HRCI credential for HR professionals working at strategic level.

spiculed

Spiculed, or spiculitic, refers to rocks composed of sponge spicules, which are needle-like structures that form the skeletal support of sponges. These rocks are often found in sedimentary environments where sponges thrived.

spiking deconvolution

Deconvolution compressing the wavelet toward a spike, sharpening resolution at the cost of noise.

spill box

A containment device provided to catch leaks at sampling points, piping connections, valves, and on barges.

spill dam

A component located around the manway cover on a tank truck, designed to hold any spilled product until it can be recovered through a drain hose.

spill point

The lowest closing contour of a trap — the level at which further hydrocarbon escapes rather than accumulating.

spin echo

A spin echo is the refocusing of spin magnetization by a pulse of resonant electromagnetic radiation.

spin flowmeter

A production logging tool with a small impeller whose rotation rate follows the fluid velocity past it.

spinal column (spine)

The interlocking bones running from the skull to the hips that support the upper body and protect the spinal cord from injury.

spinal discs

Shock-absorbing cushions that separate the vertebrae of the spine and help bear the weight of the upper body.

spine and ribs plot

The spine and ribs plot is, for a two detector density tool, the plot of long-spacing versus short-spacing count rates for different formation densities, mud cake densities and mud cake thicknesses. The plot takes its name from the spine, which is the locus of points with no mud cake, and the ribs, which show the effect of mud cake at certain fixed formation densities. The plot illustrates graphically that for a given formation density there is only one rib for all normal mud cake densities and thicknesses. Thus, although there are three unknowns, it is possible to make a correction using two measurements.

spinner flowmeter

A production logging sensor whose impeller rotation rate measures the velocity of fluid passing it.

spinner reversal

The reversal of a spinner's rotation as the tool overtakes the fluid, or as the tool passes through zero relative velocity.

spinning chain

A chain wrapped around the pipe and pulled by the drawworks to spin a connection up quickly before final torque.

spinning-drop tensiometer

An instrument that derives interfacial tension from the elongation of a drop in a rapidly rotating tube.

spiral borehole

A hole that has been drilled in a corkscrew path rather than straight, from bit whirl or an unstable assembly.

spiral-wound gasket

A metallic gasket made from a continuous strip of corrugated metal with filler cushion and wound spirally from inside to outside. The gasket has a metal ring on its inner and outer rims.

splays

Minor faults or sand bodies branching off a main structure or channel.

splice

A connection made to join two conductors together.

spline

A piecewise polynomial fitted through data points so that the curve and its slope stay continuous at every knot.

splines

Equally spaced ridges on the surface of a component that allow the component to engage another component.

split centrifugal

A centrifugal machine with a casing split so the rotor can be lifted out without breaking pipework.

split-bolt connector

A mechanical connector in which two conductors are positioned on top of each other in the split, and a nut on the connector is tightened to secure the connection.

split-spread

Split spread is an acquisition method of reflection surveying in which the source point is at (or perpendicularly offset from) the center of the geophone spread. This is also called a straddle-spread.

split-spread method

Fold is the number of sets of subsurface seismic reflections that have the same common midpoint.

splitter

A device used for sampling solid materials traveling through conveyor systems.

sponge coke

Coke with a sponge-like appearance that is produced in a coking unit.

sponge coring

Sponge coring is a sponge sleeve modification to a conventional core barrel. This sponge sleeve or liner modification of the inner core barrel is made of a tough porous polyurethane sponge which is preferentially oil wet. The sponge absorbs any oil preferentially oil wet. The sponge absorbs any oil which bleeds from the core.

sponsor

The senior person accountable for the project's business case and its funding.

sponsorship

An advocate who actively promotes someone's advancement, which mentorship alone does not do.

spontaneous combustion

The self-ignition of a flammable or combustible material through chemical reaction of its elements, without an external source of ignition.

spontaneous potential

The natural electrical potential recorded between a borehole electrode and a surface reference, abbreviated SP.

spontaneous potential, SP

Spontaneous potential is the ideal spontaneous potential (SP) that would be observed opposite a shaly, permeable bed if the SP currents were prevented from flowing. In the middle of a thick, permeable bed whose resistivity is not too high, the SP reads close to the pseudostatic spontaneous potential (PSP). In other conditions, however, the SP may be significantly less than the PSP.

spool

A short flanged pipe section used to connect or space wellhead components.

spooler

A powered reel used to handle and store a coiled tubing string off the unit.

spooling

Winding cable or coiled tubing onto its drum.

spore

A plant reproductive body preserved in sediment, used for dating and correlation.

spot

To place a measured volume of fluid at a specific depth in the well rather than circulating it throughout.

spot cylinder

A sample collected at a particular location for one specific time.

spot market

Trading for immediate or near-term delivery rather than under term contract.

spot sample

A sample taken at one specific depth in a tank or line, using a thief or weighted bottle.

spotting

Positioning a tank truck, tank car, or barge at a location such as a loading rack or dock.

spotting fluid

A pill formulated to break the filter cake seal on differentially stuck pipe and free it.

spray tower

A scrubber that contains no packing; liquid is sprayed into the tower in the form of fine droplets that contact a rising gas or vapor stream and remove contaminants from it.

spread

The layout of receiver groups relative to the source for a given shot.

spread length

The spread length is the distance from the first shotpoint to the end of the last active receiver group.

spreader

Equipment distributing load or material evenly.

spreader beam

A device that is sometimes used to change the rigging configuration for a large load from an angled lift to a straight, vertical lift.

spreading loss

The extra amplitude loss a dielectric or propagation measurement suffers because its wave spreads spherically rather than travelling as a plane wave.

sprocket

A toothed wheel driving a chain.

spud

To start the well drilling process by removing rock, dirt and other sedimentary material with the drill bit.

spud mud

The simple, usually unweighted fluid used for the first, shallow hole section.

spud, well spud

Spudding in or to spud a well means to begin drilling operations. The drill string, consisting of a drill bit, drill collars, drill pipe, and kelly, is assembled and lowered into the conductor pipe.

spurt loss

The instantaneous volume (spurt) of drilling mud that passes through a filter medium prior to the deposition of a competent and controlling filter mud cake.

square

A four-sided shape with four 90° angles and four equal sides. Also, the result of multiplying any number by itself.

square log

A log processed so that each interval is represented by a single constant value, with abrupt steps at bed boundaries.

square root

A factor of a number that, when multiplied by itself (squared), produces the given number.

square root component

A control device in which the output is the square root of the input.

square wave

A common wave shape consisting of repeating square pulses.

squeeze

To apply pump pressure so that a fluid is forced into a formation, a perforation tunnel or a void behind pipe.

squeeze cementing

Remedial cementing in which slurry is pumped under pressure through perforations or casing damage into the space behind the pipe.

squeeze job

The complete operation of setting up, testing injectivity and pressuring cement into a target zone.

squeeze manifold

A valve manifold in the surface treating lines that routes and controls fluid during a squeeze job.

squeeze packer

A retrievable packer set above the zone so squeeze pressure acts only on the target interval.

squeeze pressure

The final pressure held against the formation at the end of a squeeze, taken as evidence the target has been filled.

squeeze tool

The retrievable packer assembly through which a squeeze is pumped and which isolates the casing above it.

squeezes

Cement or chemical treatments forced under pressure into a specific interval.

squirrel cage rotor

A rotor made of conducting bars that are shorted together by end rings.

SRB

Sulfate-reducing bacteria: anaerobes that reduce sulfate to sulfide while oxidizing a carbon source, souring reservoirs and driving microbially induced corrosion.

SSMA

Sulfonated styrene maleic anhydride copolymer, a high-temperature deflocculant and filtration control additive.

SSMA copolymer

The copolymer of sulfonated styrene and maleic anhydride used as a thermally stable mud additive.

SSP

Static spontaneous potential: the full SP deflection a thick, clean, water-bearing sand would develop, against the smaller deflection actually logged.

sssv

Subsurface safety valve, which shuts the well in below surface if control is lost.

ST connector

A type of optic cable connector that is connected to equipment with a turn.

stab

To enter the pin end of one tubular into the box of another before making the connection up.

stab in

To guide one component into another so they engage, as a seal assembly into a sealbore packer.

stab-in reboiler

A type of internal reboiler.

stabbing valve

A full-opening safety valve kept ready on the rig floor to be stabbed into the string if it starts to flow.

stability

A chemical's resistance to change or disintegration.

stability clause

A provision freezing the fiscal terms, or compensating the investor if the state changes them.

stability meter

The instrument that measures the electrical stability of an oil-base mud by raising voltage across a probe until the emulsion conducts.

stability triangle

The imaginary geometric figure formed by connecting the three support points of a forklift (at the two front wheels and the center of the rear axle at the steering pivot point). The center of gravity must remain within this triangle to prevent tipping.

stabilization

The condition in which a well's rate and pressure have stopped changing appreciably with time.

stabilization system

The column and reboiler driving light ends out of condensate so it can be stored safely.

stabilized

Said of a well flowing at a rate and pressure that no longer change measurably through a fixed choke.

stabilized cat-cracked gasoline

Cat-cracked gasoline from which the lighter components have been removed.

stabilized gas well

A gas well flowing at a rate and pressure that are no longer changing appreciably with time.

stabilizer

In drilling, a piece of downhole equipment in the BHA that mechanically stabilizes the assembly in the borehole to avoid unintentional sidetracking, vibrations, and ensure hole quality. In refining, a distillation tower used to separate light components to control a product's initial boiling point.

stabilizer bottom temperature

The temperature at the stabilizer's base, which sets the product's vapor pressure.

stabilizer system

The stabilizer column and its ancillaries, removing light ends from liquid product.

stabilizer, drilling stabilizer

A drilling stabilizer is a piece of downhole equipment used in the bottom hole assembly (BHA) of a drill string. It mechanically stabilizes the BHA in the borehole to avoid unintentional sidetracking and vibrations, which helps ensure the quality of the hole being drilled.

stable arch

The self-supporting shell of bridged sand grains that forms around a perforation and holds without producing sand.

stable emulsion

An emulsion whose interfacial film resists coalescence, needing heat, chemical or electricity to break.

stable state

A condition in multivibrator circuits in which one of the two amplifier stages is conducting and the other stage is not conducting.

stack

The sum of traces sharing a common midpoint after moveout correction, producing one output trace.

stack array

A receiver arrangement designed so that stacking suppresses ground roll.

stack damper

A device inside the stack that is adjusted to increase or decrease the amount of air and gas flow through a furnace.

stacked trace

The single trace resulting from summing a gather, with noise reduced and signal reinforced.

stacking velocity

The velocity that best flattens a reflection across a common midpoint gather, found by moveout analysis.

staff retention

Keeping the people the organization needs, measured against the cost of replacing them.

stage compression

Compression split across stages with cooling between, keeping discharge temperature and ratio within limits.

stage gate, stage gate process

A stage gate process is a project management technique in which the development of an exploration and production asset is divided into stages, separated by gates.

stage separation

Passing the wellstream through two or more separators in series at successively lower pressures.

stage-gate process

Advancing a project through defined phases, with a decision to continue at each boundary.

staged fracturing

Fracturing a long interval in a sequence of separate treatments, each isolated from the last.

stages of conflict

The progression from latent difference through emergence to escalation and outcome.

staggered stop

A defensive driving technique that involves stopping at least five or six feet behind the pavement markings when you stop in the lane closest to the center one. This protects your vehicle from large vehicles or others that may make short left turns.

stainless steel

Steel alloyed with chromium to resist corrosion, at the cost of price and of chloride cracking.

stakeholder

Any person or organization that is actively involved in the project, whose interests may be positively or negatively impacted by the project or who may exert influence over the project.

stakeholder bloc

A group whose members act together, so they must be engaged as one.

stakeholder engagement

The planned interaction that keeps stakeholders informed and supportive.

stakeholder engagement life cycle

The sequence from identification through consultation to sustained relationship over a project's life.

stakeholder expectations

What stakeholders believe they will get, which must be managed as actively as scope.

stakeholder mapping

Identifying who is affected by or can affect a project, and where each one stands.

stakeholder prioritization

Deciding where engagement effort goes, since not every stakeholder needs the same attention.

stand

Two or three joints of pipe left made up together and racked in the derrick during a trip.

standard

A single piece of metal precisely machined to a specific size.

standard batch

A corrosion inhibitor batch pumped down the tubing and allowed to fall or be displaced, coating the string as it goes.

standard competency models

standard deviation

The standard deviation is a statistic that measures the dispersion of a dataset relative to its mean and is calculated as the square root of the variance.

standard deviation rule

The approximation that most observations fall within two or three standard deviations of the mean.

standard of performance

The care an operator owes the venture, usually good oilfield practice rather than perfection.

standard temperature and pressure

An agreed reference temperature and pressure at which volumes are reported so that measurements can be compared.

standard threshold shift

The deviation, in decibels, of a measured hearing threshold level from one previously established.

standardization meetings

Assessors hold standardization meetings to identify any discrepancies between assessors in their judgment of candidates' evidence and allow adjustments to be made to remedy them. As well as reducing subjectivity among assessors, they help to improve the consistency of judgments and allows internal verifiers to identify and disseminate good practice. Standardization meetings should take place throughout the assessment process and records of these meetings, including any feedback to assessors, should be kept as evidence of internal verification activity.

standby attendant

A person who remains outside a storage tank during cleaning and maintenance work to monitor the workers who are inside the tank and tank conditions and notify rescue personnel when necessary.

standing valve

The valve in a rod pump closest to the bottom of the pump. It is in the part of the pump that does not move up and down.

standoff

The gap between a shaped charge and the surface it is fired at.

standpipe

A vertical pipe connected to a pressurized water supply system that is used to secure a uniform pressure.

star

A type of network topology in which all of the cables are routed to a central point, where they connect to a hub.

star formation

A grounding scheme in which grounds for multiple controllers are each wired directly to a grounding bus.

starch

A natural polysaccharide used to control filtration in water-base muds from fresh to saturated salt.

startup procedure

The ordered method for bringing equipment from shutdown into service.

statement of cash flows

The statement reconciling profit to cash actually received and paid.

static aging test

Heating a mud sample in a sealed cell without agitation, to see what temperature alone does to its properties.

static and dynamic reservoir modelling

The pairing of a fixed geological description with a flow model that evolves over time.

static correction

A constant time shift applied to a trace to remove the effect of elevation and the weathered layer.

static dissipative materials

Static dissipative materials have an electrical resistance between insulated and conductive materials.

static electricity

Accumulated charge, which on non-conductive liquid can spark into flammable vapor.

static filter press

The pressurized cell in which filtration is measured with the fluid at rest against the filter medium.

static filtration

Filtration in which the fluid is not moving across the filter surface, so the cake builds without being eroded.

static fluid level

The depth to which liquid stands in the annulus of a shut-in well once it has stopped moving.

static head

Pressure due to the height of a liquid column alone.

static mixer

A blending device with fixed blades, contained in a blend header or meter tube upstream of a sample probe, that causes mixing of the fluid stream.

static postures

A type of awkward posture in which the same posture or position is held throughout an exertion. Static postures put increased loads or forces on the muscles and tendons, which contributes to fatigue. Examples of static postures include gripping tools that cannot be put down, holding the arms out or up to perform tasks, or standing in one place for prolonged periods.

static pressure

The force exerted by a fluid confined within a tank, pipe, or duct as measured by a gauge. In HVAC, the pressure of air at rest inside a duct.

static reservoir

A reservoir considered at rest, before or between production periods.

static reservoir model

A computer model of a reservoir created by geologists and geophysicists that provides a static description of the reservoir prior to production, used for improving resource estimation and making field development decisions.

static reservoir modelling, static reservoir model

Static reservoir modelling is those reservoir modelling activities up to the point when a simulation model is ready to simulate the flow of fluids.

static seal

A seal between two parts that do not move relative to each other.

static SP, static spontaneous potential, SSP

The static spontaneous potential (SSP) is the ideal spontaneous potential that would be observed opposite a permeable bed if the SP currents were prevented from flowing and any shaliness in the bed were ignored. The SSP is equal to the electrochemical potential.

static spontaneous potential

The full SP deflection a clean permeable bed would show if no SP current could flow and the bed carried no shale, abbreviated SSP.

statics

Statics involves the correction for near surface velocity variations using surface velocity modeling and refraction analysis. This process uses the first arrival times of refracted seismic energy to compute near surface velocities and layer thicknesses.

statics problems

Statics problems can include variations in elevation, near-surface low-velocity-layer (weathering) thickness, weathering velocity, and/or reference to a datum.

stationarity

The assumption that a property's statistical behavior is the same everywhere in the area being estimated.

stationary

Not moving.

stationary blade

A fixed blade directing flow onto the moving blades in a turbine or compressor.

stationary component

A part that does not move, as distinct from the rotating element it seals or guides.

stationary contact

The fixed contact a moving contact closes onto.

stationary field generator

A type of AC generator in which direct current is fed to the stator and the output voltage from the generator is taken from the rotor through slip rings and brushes.

stationary part

A component that does not move.

stationary phase

The fixed material a sample passes over in chromatography, which separates the components.

stationary seal

The fixed half of a seal.

stationary slips

The fixed slip set at the base of a snubbing jack, which holds the pipe while the travelling slips reset.

stationary snubbers

The fixed slips on a snubbing unit that grip the pipe under light-pipe conditions, when the well is pushing the string upward.

statistical control

Monitoring a process by whether its variation stays within expected limits.

statistical process control (SPC)

A technique of using statistical methods to help identify and eliminate problems in some industrial processes.

statistical significance

Whether an observed difference is unlikely to have arisen by chance alone.

statistical vs. practical significance

Whether a difference is real against whether it is large enough to act on.

statistics

The branch of mathematics dealing with the collection, analysis and interpretation of quantitative data.

statoil

The former name of Norway's national oil company, now Equinor.

stator

The fixed, or non-moving, part of a motor or AC generator.

stator coil

A coil in the stationary winding of a machine.

stator field

The magnetic field produced by the stationary winding.

stator magnetic field

The magnetic field produced by the stationary winding.

stator winding

The stationary winding in a motor or generator.

STB

Stock tank barrel: a barrel of oil measured at surface stock tank conditions, after solution gas has been liberated.

steady state

A condition in which the quantities of interest no longer change with time.

steady state conditions

Operating conditions in which a boiler operates at a constant load and consistently produces a designated steam output with little or no fluctuation.

steady-state behavior

Flow in which rate and pressure are both constant with time.

steady-state conditions

Conditions in a system that remain constant over a period of time.

steam

Water in the vapor phase, and in practice a mixture of vapor and entrained liquid water whose proportions define its quality.

steam chamber

The heated region of reservoir around an injector in which mobile steam persists.

steam chest

A collection area designed to distribute steam to the turbine control valves.

steam cracker

The unit thermally breaking feedstock into ethylene and other olefins.

steam cracking

Thermally breaking hydrocarbon feedstock into ethylene and other olefins.

steam cycle

In a power plant, the fluid flow path from the boiler, through the turbine, through the condenser, and back to the boiler.

steam drum

The vessel at the top of a boiler where steam separates from water.

steam ejectors

Devices used to pull uncondensed vapor from the top of a vacuum tower or from a condenser.

steam header

The main distributing steam to its users.

steam injection

Injecting steam to heat heavy oil and cut its viscosity enough to flow.

steam jet

A device that uses the flow of steam to move another fluid, such as air.

steam jet air ejector

A device that can be used to establish a vacuum and remove non-condensable gases from a condenser.

steam management

The planning and control of heat and fuel across a steam injection project.

steam methane reforming

Reacting methane with steam to yield hydrogen and carbon dioxide, still the cheapest route and the dirtiest.

steam piping

Pipework carrying steam, which must allow for thermal expansion and drain condensate.

steam soak

The shut-in period after steam injection in a cyclic treatment, during which the heat spreads before the well is produced.

steam stop valve

The isolation valve on a steam main.

steam trap

In a steamflood, the cool oil- and water-saturated zone ahead of the steam front that resists steam breaking through to the producer.

steam traps

Devices located at low points in steam lines where condensate naturally collects. Designed to remove water from steam lines without allowing steam to escape.

steam turbine

A turbine driven by expanding steam.

steam valve

A valve on steam service.

steam-assisted gravity drainage (SAGD)

A process used to recover bitumen that is too deep to mine. A pair of horizontal wells is drilled from a central well pad. In a plant nearby, steam generators heat water and transform it into steam. The steam then travels through above-ground pipelines to the wells. It enters the ground via the steam injection well and heats the bitumen to a temperature at which it can flow by gravity into the producing well. The resulting bitumen and condensed steam emulsion is then piped from the producing well to the plant, where it is separated and treated. The water is recycled for generating new steam.

steam-oil ratio

The volume of steam injected per volume of oil produced, the efficiency measure of a thermal recovery project, abbreviated SOR.

steam/water cycle

The flow paths of steam and water through the various steam systems within a power plant.

steamflood

Continuous injection of surface-generated steam through dedicated injectors to heat the reservoir and drive oil to producers.

steamflooding

Injecting steam to heat and thin heavy oil so it will flow.

stearate

A salt of stearic acid, one of the long-chain fatty acids.

steep dip

Bedding inclined enough to complicate both drilling and seismic imaging.

steeper

Of greater gradient, as a decline curve or a structural dip.

steepest descent

Steepest descent is a special case of gradient descent where the step length is chosen to minimize the objective function value.

steeply dipping

Inclined enough that imaging and drilling both become harder.

steerable

Able to be directed while drilling, without tripping to change the assembly.

steerable motor

A mud motor with a bent housing, which builds angle when sliding and drills straight when the string is rotated.

stem

The part of a valve that connects the handwheel to the disc and moves the disc to control flow.

stem indicator

A marked rod or exposed stem showing how far a valve is open.

stem nut

A sleeve with threads inside and splines outside that transmits the motion of a drive sleeve to a valve stem.

step distance, step length

Step distance, or step length, defines the depth increment to be used between successive rounds of correlations. This is often set to half the correlation interval, giving a 50% overlap.

step input

A sudden change in the value of a process variable.

step profile

An invasion model in which resistivity changes abruptly from flushed zone to undisturbed zone, with nothing in between.

step rate test

An injection test run at a series of increasing rates, each held long enough to stabilize, to find the pressure at which the formation fractures.

step signal

Signals such as steps and pulses that only occur once are called single-shot or transient signals. The step indicates a sudden change in voltage, such as what you would see if you turned on a power switch.

step-down transformer

A transformer that decreases or reduces voltage as it induces voltage from its primary winding to its secondary winding.

step-out drilling

This process of drilling involves moving outward from the initial wildcat well to define the limits of the reservoir.

step-up transformer

A transformer that increases voltage as it induces voltage from its primary winding to its secondary winding.

step-up transformers

A transformer in which the output voltage is greater than the input voltage.

stepladder

A self-supporting ladder consisting of two elements hinged at the top.

sterane

A biomarker derived from steroids, used to fingerprint source rock and oil.

stereogram

A two-dimensional, circular representation of a sphere giving a three-dimensional representation of a solid object or surface, in which lines of longitude and latitude form a coordinate system (a net) on which projections of great and small circles occupy the equatorial plane.

stereonet

A graphical tool representing the hemisphere of a globe, used for the presentation, analysis, and interpretation of three-dimensional directional data such as planes and lines.

stick/slip

Motion that alternates between sticking and sudden release, rather than moving smoothly.

stiction

The effect of excessive static friction. Stiction causes analog actuators and actuated equipment to move in jets even when the input control signal is smoothly increasing or decreasing.

stimulation

Any treatment intended to raise a well's productivity above what it currently delivers.

stimulation by-product

A compound formed when a treatment fluid reacts with something already in the formation, rather than with its intended target.

stimulation fluid

The fluid pumped in a stimulation treatment, most often the acid system of a matrix treatment.

stimulation treatment

A pumped job improving inflow, by fracturing or by dissolving damage.

stimulation, well stimulation

A stimulation is any treatment performed to restore, or enhance, the productivity of a well. Stimulation treatments fall into two main categories, hydraulic fracturing treatments and matrix treatments.

stinger

A projecting tube on a tool that enters and seals in another component.

stirrer

A powered agitator mixing a liquid.

stochastic analysis

Analysis that treats inputs as random variables and produces a distribution of outcomes rather than a single answer.

stochastic methods

Techniques that generate many equally probable realizations by sampling random variables within statistical constraints.

stochastic modeling

Building reservoir models by stochastic interpolation between wells, producing many realizations rather than one.

stock market and trading venues

The exchanges and platforms on which shares are bought and sold.

stock tank

The atmospheric tank in which treated oil is held before sale.

stock tank barrel

A barrel of oil measured at stock tank conditions, abbreviated STB.

stock tank oil initially in place, STOIIP

STOIIP is the abbreviation for Stock Tank Oil Initially in Place.

stock-tank original oil in place

The oil originally in the reservoir, expressed as the stock tank volume it would occupy at surface, abbreviated STOIIP.

STOIIP

The abbreviation for Stock Tank Oil Initially In Place.

stoker

A type of combustion equipment that is designed to supply solid fuel, such as coal or wood, to a boiler.

Stoneley permeability

Permeability inferred from the attenuation and slowing of the borehole Stoneley wave as fluid is squeezed into and out of the formation.

Stoneley velocity

Stoneley velocity is the velocity of Stoneley waves.

Stoneley wave

A high-amplitude boundary wave, or interface wave, that typically propagates along a solid-solid interface.

stop valve

A valve for isolation, not intended to be left part open.

stopcock

A small manual valve on laboratory or sampling glassware.

stopple

A hot-tap repair method that plugs a live pipeline internally so a section can be isolated without a shutoff valve.

storage play

Any trade whose profit comes from holding barrels through time rather than moving them.

storage reservoir

A depleted field or aquifer used to store gas.

storage tank

A tank used to store a finished product ready for distribution, or to hold treated oil before transfer by a LACT unit.

storativity

The capacity of a formation to store and release fluid as pressure changes.

storm choke

A subsurface safety valve held open by flow and closed by the velocity of an uncontrolled flow, needing no surface control line.

storm packer

A heavy-duty retrievable packer set to secure the wellbore when operations are suspended, typically for weather.

stoss

Stoss refers to the side of a landform that receives, or has received, the thrust of a flow.

STP

Standard temperature and pressure — the agreed reference conditions at which volumes are reported.

straddle stacker

A type of forklift that conserves space by straddling the load.

straight angle

A180 angle.

straight ladder

A non-adjustable ladder of a fixed length.

straight run

A material that has been separated, but has not undergone any chemical changes.

straight run gasoline

A gasoline feed from the crude unit that is sent to the gasoline blending area.

straight-run asphalts

Semi-solid to solid products that remain after the lighter petroleum distillates and the heavier, oily distillates have been removed. Also called asphalt cements.

straight-run naphtha

Naphtha from primary distillation only, used as reformer feed or petrochemical feedstock.

straight-tube heat exchanger

A type of shell and tube heat exchanger that has straight tubes that extend from a tube sheet at one end of the heat exchanger to a tube sheet at the other end.

straightening vane

A bundle of tubes inserted in the meter tube upstream of the meter¬ing device to eliminate turbulence.

straightening vanes

Plates in a separator which reduce or eliminate gas turbulence.

strain

A normalized measure of deformation representing the displacement between particles in a body relative to a reference length.

strain gauge

A sensor measuring deformation, from which load or pressure is derived.

strainer

A device or vessel used to remove solid particles from a fluid stream, such as in a LACT unit or upstream of a metering device.

stranded asset

An asset that loses value before the end of its expected life because conditions change.

stranded conductor

A conductor that consists of a group of wires that are usually twisted together and not insulated from each other.

stranded reserves

Discovered hydrocarbons with no economic route to market.

strap

To measure the actual length of each joint as a string is run, and keep a running tally.

strapping

Measuring the dimensions of a lease tank to accurately determine the volume of oil at any measured depth.

strapping a tank

Following a standard method for measuring a tank to determine its exact volumetric capacity.

strapping tape

The graduated steel tape used to measure a tank's dimensions so its gauge table can be built.

strata

Layers of sedimentary rock, each distinguishable from those above and below; singular stratum.

stratabound fracture

A stratabound fracture is a fracture that terminates at geological strata.

stratal

Relating to the layering of strata.

stratal reflector

A seismic reflector following a depositional layer rather than cutting across it.

strategic alignment

Ensuring people practices support what the business is actually trying to do.

strategic fit

How well an opportunity matches the company's capabilities and direction.

strategic intent

The ambition that stretches an organization beyond its current resources.

strategic momentum

Sustaining progress on a strategy after the initial announcement and enthusiasm fade.

strategic planning process

The structured sequence by which an organization sets and reviews direction.

strategic sourcing

Sourcing based on total cost and market analysis rather than on price alone.

strategic vs. tactical budgeting

Budgeting to fund long-term direction against budgeting to run the coming period.

strategic workforce planning

Aligning that forecast with business strategy rather than with last year's headcount.

stratification

Stratification ordinarily describes the layering that occurs in sedimentary rocks. Stratification, or bedding layers, are greater than one centimeter in thickness. Laminations are less than one centimeter thick.

stratified flow

A two-phase regime in horizontal or near-horizontal pipe where gas runs along the top and liquid along the bottom.

stratigraphic

Stratigraphy is the study of the history, composition, relative ages and distribution of rock strata.

stratigraphic analysis

The study of the composition, age relations and distribution of strata to reconstruct geological history.

stratigraphic column

The vertical succession of units at a location, in depositional order.

stratigraphic correlation

Stratigraphic correlation is the demonstration of the equivalency of stratigraphic units, normally involving a correlation of geological events between nearby wells displayed on a cross-section.

stratigraphic feature

A feature of the succession rather than of deformation, such as a channel or a pinchout.

stratigraphic interpretation

Reading depositional history and correlation from the succession.

stratigraphic modeling

Modeling how a succession was built, to predict reservoir presence away from control.

stratigraphic sequence

A succession of strata bounded by surfaces of the same rank.

stratigraphic surface

A surface separating units, marking a change in depositional conditions.

stratigraphic trap

A trap formed by lateral or vertical change in rock type — a pinchout, a facies change or an unconformity — rather than by structure.

stratigraphic traps

A type of geologic trap, created by changes in rock lithologic characteristics, such as porosity or permeability.

stratigraphic unit

A named body of rock defined by its position in the succession.

stratigraphic units

Stratigraphic units are a sequence of rock beds, a specific rock type or group of rock types that can be traced over a fairly broad region.

stratigraphy

The study of the history, composition, relative ages, and distribution of rock strata.

stratigraphy, stratigraphic

Stratigraphy is the study of the history, composition, relative ages and distribution of rock strata.

stratum

A stratum is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as either bedding surfaces or bedding planes.

streamer

The buoyant cable of hydrophones towed behind a marine seismic vessel.

streamer feathering

The sideways drift of a towed streamer off the vessel's heading, caused by cross-currents.

streamtube modelling

A fast approximation that routes flow along streamlines instead of solving a full grid.

strength retrogression

The loss of set cement compressive strength, and rise in permeability, that occurs above about 230°F.

stress

A physical quantity that expresses the internal forces that neighboring particles of a continuous material exert on each other; the result of applied forces.

stress corrosion cracking

Cracking that occurs only when a susceptible alloy, a specific corrosive environment and tensile stress are present together.

stress magnitude

The size of a stress component, needed with its direction to predict rock behavior.

stress measurement

Determining the magnitude or direction of in-situ stress, usually from an injection test.

stress tensor

The full description of stress in three dimensions, needed because rock cares about direction.

stress vs. anxiety

A response to an identifiable pressure against persistent apprehension without one.

stress-induced anisotropy

Directional variation in shear velocity around a borehole caused by unequal horizontal stresses rather than by rock fabric.

stressor

The specific demand or condition producing the stress response.

strike

Strike is the direction of a line formed by the intersection of a fault, bed, or other planar feature with a horizontal plane.

strike direction

A geological feature's strike is the azimuth of an imagined horizontal line across the plane.

strike fault

A fault whose trace runs parallel to the regional strike of the beds it cuts.

strike slip, strike slip fault

A strike slip fault is a fault in which rock strata are displaced mainly in a horizontal direction, parallel to the line of the fault.

strike-slip fault

A steeply dipping fault on which the blocks move horizontally past each other.

strikers

Movable blocks on the front of a torque switch; used to adjust the amount of torque that the switch responds to.

string shots

A set of sources, either downhole or at the surface, that are repeated a number of times to help establish velocity models for a play.

stringer

A stringer is a very thin rock layer; typically this is comprised of sandstone.

strip chart

A chart made on a long strip of paper that can be used to show operating conditions over a period of time.

strip gun

A perforating gun whose charges are mounted on an open strip carrier rather than enclosed in a sealed tube.

stripper

In electrical work, a tool used to remove insulation from a conductor. In processing, a vessel that uses hot vapor to separate lighter, more volatile components from heavier ones. In catalytic cracking, a device that uses steam to remove hydrocarbon vapors from spent catalyst. In amine treatment, a component where acid gases are removed from rich amine.

stripper (still)

A vertical pressure vessel where rich amine and steam are brought together to remove acid gases from the amine solution.

stripper column

Column driving an absorbed component back out of a solvent with heat or stripping gas.

stripper rubber

The elastomer element that seals around coiled tubing or pipe while it is moved through a live wellhead.

stripper tower

A distillation tower that separates light components from a feed, but does not produce a liquid overhead product.

stripping

Moving pipe into or out of a well through closed preventers while pressure is contained.

stripping gas

Warm gas percolated through glycol being regenerated to help remove water not removed by the distillation process, enabling purification of glycol to nearly 100%.

stripping ram

A ram preventer with elements designed to seal on pipe while it is being moved through them.

stripping steam

Steam that is added to the bottom of a distillation tower in order to vaporize the light ends in the liquid.

stripping vapor

Vapor passed through a solvent to carry absorbed components out of it.

stroke

In pumping, one complete rotation of the crankshaft. In compressors, the movement of the piston from one end of the cylinder to the other.

strokes per minute

The cycle rate of a reciprocating machine — a pumping unit's polished rod or a mud pump's liners, abbreviated SPM.

strontium

An element whose sulfate forms scale, and whose isotopes date and correlate strata.

structural

Pertaining to the geometry and arrangement of rock bodies produced by deformation.

structural analysis

The interpretation of folds, faults and their geometry to establish how a region was deformed.

structural conflict

Conflict caused by how work and incentives are arranged, not by personalities.

structural contour

A contour of equal depth or elevation on a surface, from which closure is read.

structural contour map

A map of depth or elevation on a horizon, from which closure and volume are read.

structural dip

The tilt of beds caused by deformation rather than by original deposition.

structural formula

A representation of the number, kinds, and arrangement of atoms in a molecule.

structural geology

The study of rock deformation — folds, faults, fractures — and what it means for trapping.

structural reconstruction, restoration or palinspastic restoration

Structural reconstruction, or palinspastic restoration, is a technique used to progressively undeform a geological section in an attempt to validate the interpretation used to build the section.

structural shale

Structural shale is a particular type of shale distribution in which the shale exists as grains within a rock framework, in contrast to dispersed shale and laminar shale.

structural steering

Steering a horizontal well by tracking its position within the structural model rather than by formation markers alone.

structural trap

A trap created by deformation — a fold or a fault — that closes the reservoir against a seal.

structural trend

A structural trend indicates the compass direction in which the longest axis of the structure is aligned.

structure

A geological feature produced by deformation, such as a fold, fault or dome.

structure map

A contour map of the elevation of a chosen geological marker.

structure, structural, tectonics

Tectonics is concerned with the processes which control the structure and properties of the Earth's crust, and its evolution through time.

structure, tectonics

Tectonics is concerned with the processes that control the structure and properties of the Earth's crust and its evolution through time.

structured interview

An interview using the same planned questions and scoring for every candidate.

structured packing

Fabricated sheet packing giving a predictable surface and low pressure drop, unlike dumped random packing.

stub-up

The part of a length of conduit that is bent in a different direction when a stub bend is made.

stuck

Unable to move a string in the hole, by rotation, by pulling or at all.

stuck pipe

Drillstring that can no longer be rotated or moved vertically in the hole.

student loan assistance

Employer contributions toward repaying an employee's education debt.

stuffing box

The area between a pump shaft and casing that contains packing material or a mechanical seal. In beam pumping, the surface connection that seals the production tubing with packing around the polished rod to restrict leakage.

stylolite

A serrated, interlocking dissolution seam concentrating insoluble clay and iron oxide residue, common in carbonates.

styrene

C6H5CH=CH2, an aromatic monomer that polymerizes to polystyrene.

sub

Any short connecting component in a drillstring — a crossover, a bit sub, a float sub.

subaerial

Subaerial relates to something that exists or occurs in the open air or on Earth's surface, rather than underwater or underground.

subaerial unconformity

A surface of exposure and erosion, marking a sequence boundary.

subaqueous

Formed or deposited under water.

subcontractor

A firm engaged by the main contractor to perform part of the work.

subcooler

Exchanger taking a liquid below its boiling point so it does not flash in the line ahead.

subcritical conditions

Conditions below the critical point of 705 degrees Fahrenheit and 3206 psi.

subculture

A distinct set of norms within one part of an organization.

subduction

The descent of one lithospheric plate beneath another into the mantle at a convergent margin.

subduction zone

Where one plate descends beneath another, generating arcs and forearc basins.

subject matter expert (SME)

submarine fan

A submarine fan is a cone-shaped accumulation of sediment found on the deep ocean floor. These are formed by turbidity currents and sediment gravity flows.

submersible

Operating below the fluid surface, as an electric submersible pump.

submersible drilling rig

A mobile offshore unit that is floated to location and then ballasted down until it rests on the seabed, for shallow water only.

submersible pump

An electrically driven pump set downhole, used for high rates where rods will not serve.

subordinated shareholder debt

Sponsor lending that ranks behind bank debt, serving as equity while remaining repayable.

subproject and master project

A project nested inside a larger one, and the plan that consolidates them.

subroutine

A separate PLC program that runs when directed to by the main PLC program or by another subroutine.

subsalt

A play in which the reservoir lies beneath a salt body.

subsea

Equipment installed on the seabed rather than on a surface platform.

subsea bop

The blowout preventer stack landed on the seabed wellhead.

subsea equipment

The trees, manifolds and controls installed on the seabed.

subsea isolation valve

A remotely operated valve on the seabed that shuts in a flowline or riser in an emergency, abbreviated SSIV.

subsea manifold

The seabed structure gathering flow from several wells into one line.

subsea tree

The valve assembly installed on a seabed wellhead to control production.

subsea well

A well whose wellhead, tree and control equipment sit on the seabed rather than on a platform.

subsea wellhead

The wellhead on the seabed rather than at surface.

subsidence

The downward movement of the Earth's surface relative to a datum.

subsidence curve

The plot of basin sinking against time, from which tectonic mechanism is read.

subsidence history

The record of how a basin sank through time.

subsides

Sinks, as a basin floor does under sediment load.

subsidiary hazard

A hazard other than the most dangerous hazard posed by a material.

substance abuse policy

The rules on drugs and alcohol at work and the consequences of breaching them.

substation

A facility in which voltage is changed or transformed to accommodate one or more electrical distribution systems.

substation shunt reactor

A reactor connected across the busbars to absorb reactive power.

substitution cipher

A simple cipher replacing each character with another, easily broken but useful for teaching.

subsurface

Everything below ground surface or seabed, the domain the upstream business works blind in.

subsurface data

The logs, cores, tests and seismic from which the reservoir description is built.

subsurface design

The reservoir and well side of a development plan, as opposed to the facilities.

subsurface development plan

The reservoir and well plan for developing a discovery.

subsurface formation

A rock unit below surface.

subsurface geology

The geology below surface, known only through wells and remote measurement.

subsurface information

Data about the rock below surface.

subsurface lockdown

Freezing the reservoir and well assumptions so facilities design can proceed on a stable basis.

subsurface plan

The reservoir and well component of a field development plan.

subsurface pressure

Any pressure measured below surface in a well — hydrostatic, pore or fracture pressure.

subsurface pump

The downhole element of a rod-pumped well, as distinct from the surface unit driving it.

subsurface reservoir

The rock volume below ground holding the accumulation.

subsurface rock

Rock below surface, known only through wells and remote measurement.

subsurface safety valve (SSSV)

A downhole valve that shuts the tubing automatically if surface control is lost, abbreviated SSSV.

subsurface structure

The deformed arrangement of rock at depth.

subsurface surface-controlled safety valve (SSCSV)

A downhole safety valve operated from surface through a control line, closing automatically if that control is lost.

subsurface water

Water present below surface, whether formation water or invaded filtrate.

subsystem

A functional part of a larger system.

subtidal

Permanently below low tide.

successful efforts accounting

Capitalizing only the cost of wells that find reserves, expensing the dry holes as incurred.

succession planning

Identifying and preparing people to fill critical roles before they fall vacant.

successions

The chronological layers of sedimentary rock that accumulate in an area over time, influenced by geological processes such as tectonics, sediment supply, and changes in sea level. In undisturbed sequences, newer units are typically above older units.

sucker rod

A steel or fiberglass rod, coupled into a string, that transmits the surface pumping unit's stroke to the downhole pump.

sucker rod pump

A reciprocating downhole pump driven from surface through a rod string, the oldest and most common form of artificial lift.

sucker rod pumping

Artificial lift reciprocating a downhole pump on a sucker rod string.

sucker rod string

The rod column driving a downhole pump, named for the sucker rods it is built from.

suction discharge valve

The valve set in a compressor cylinder admitting and releasing gas each stroke.

suction eye

The area at the center of an impeller where fluid is drawn into a pump.

suction gas

Gas entering a compressor, whose pressure and liquid content decide what the machine survives.

suction head

The pressure available at a pump's suction, which must exceed vapor pressure or the pump cavitates.

suction header

The manifold collecting flow into a compressor's suction, sized to keep velocity and pulsation down.

suction line

A pipe that is used to discharge material from a tank.

suction piping

The pipework feeding a pump's suction, whose losses set available suction head.

suction pit

The mud tank from which the rig pumps draw their suction.

suction port

The opening fluid enters a machine through.

suction pressure

The pressure at the suction port of a compressor.

suction scrubber

Vessel removing liquid from gas immediately before a compressor, protecting it from slugs.

suction side

The inlet side of a machine.

suction stroke

The part of a reciprocating cycle that draws fluid in.

suction valve

The valve admitting fluid to a pump or compressor.

suction valves

Valves which open to allow gas to enter the cylinder.

suez transit charge

The toll levied for passing through the Suez Canal, weighed against the longer Cape route.

suezmax

The largest tanker able to transit the Suez Canal fully laden, around one million barrels.

suite, logging suite

Several wireline logging runs acquired in succession within the same activity stage, such as at a casing point.

sulfate resistance

A set cement's ability to withstand attack by sulfate ions in formation water without expanding and cracking.

sulfate-reducing bacteria

Anaerobic bacteria that reduce sulfate to sulfide, generating hydrogen sulfide in the process, abbreviated SRB.

sulfate-resistant cement

Cement with tricalcium aluminate limited by specification, so sulfate brines cannot attack it and cause expansion.

sulfide

A compound containing the S2− ion; hydrogen sulfide is its highly toxic gaseous form.

sulfide scavenger

An additive that converts dissolved sulfide into an insoluble, non-hazardous compound.

sulfide stress cracking

Sudden brittle failure of high-strength steel exposed to moist hydrogen sulfide, a form of hydrogen embrittlement.

sulfide test

The API procedure, run on a Garrett gas train, that measures soluble sulfide in the mud filtrate.

sulfides

A sulfide is a binary compound of sulfur with another element.

sulfidizing

A stage of catalyst regeneration in which sulfides are applied to the surface of the catalyst.

sulfite

An oxygen scavenger added to injection water to prevent corrosion.

sulfonate

A surfactant class used in drilling fluids and chemical flooding.

sulfonated asphalt

Asphalt reacted with sulfite to add anionic sulfonate groups, making it dispersible in water-base mud.

sulfonated polystyrene-maleic anhydride copolymer

A sulfonated copolymer of styrene and maleic anhydride used as a high-temperature deflocculant, abbreviated SSMA.

sulfur compound

A sulfur-bearing molecule, corrosive in service and a poison to catalyst.

sulfur concentration

The proportion of sulfur, which determines processing requirement and price.

sulfur content

The proportion of sulfur in a crude or product, which sets processing cost and specification.

sulfur diesel

Diesel classified by its sulfur content, which regulation has progressively reduced.

sulfur diesel fuel

Diesel classified by sulfur content, progressively restricted by regulation.

sulfur dioxide (SO₂)

A toxic gas that is produced when fuel products containing H₂S are burned.

sulfur light crude

A low-density crude that nonetheless carries appreciable sulfur, so it is light but sour.

sulfur oxide

An oxide of sulfur formed on combustion, regulated as an emission and corrosive when wet.

sulfur oxides

The products formed when sulfur combines with oxygen. When released to the environment, they create a form of air pollution.

sulfur recovery

Converting recovered hydrogen sulfide to elemental sulfur rather than flaring it.

sulfur recovery plant

Plant converting hydrogen sulfide from sweetening into elemental sulfur rather than flaring it.

sulfur recovery unit

The plant converting hydrogen sulfide into elemental sulfur.

sulfuric

Of sulfuric acid, used in alkylation and produced from recovered sulfur.

sulfuric acid

A type of catalyst that is commonly used in alkylation units.

sulphide

A sulfur compound, most often hydrogen sulfide, which is both corrosive and acutely toxic.

summary slide

The slide stating the conclusion, which many audiences read first.

summation

Adding traces together, the stacking step that improves seismic signal to noise.

summation of fluids method

Determining core porosity by adding the measured volumes of gas, oil and water recovered from the sample.

summation-of-fluid

A porosity method summing the fluid volumes measured on a core sample.

summing amplifier

An op amp circuit whose output voltage is the sum of it input voltages. Where all of the input voltages are applied to the inverting terminal, the circuit is known as an inverting summing amplifier.

summing component

A control device in which the output is the sum of two or more inputs.

summing junction

A point on the inverting input terminal of an op amp circuit at which the potential will equal the potential at the reference junction.

Summit Energy (workforce case)

The fictional energy company used as the workforce and talent management case.

sump

A low collecting point liquid drains to before being pumped away.

supercharging

Increased sand face pressure caused by drilling fluid filtrate leak-off, resulting in excess pressure due to mud filtrate invasion in low-permeability formations.

supercritical

Above the critical pressure and temperature, where liquid and gas are indistinguishable.

supercritical boiler

A boiler that normally operates at conditions that are above the critical point, at which the density of water and the density of steam are the same.

supercritical conditions

Conditions above the critical point of 705 degrees Fahrenheit and 3206 psi.

superficial velocity

A phase's volumetric rate divided by the whole pipe cross section, as if that phase filled the pipe alone.

superheated steam

Steam that has been heated above the saturation temperature.

superheater

A component that heats steam above the saturation temperature.

supermajor

One of the handful of largest publicly traded integrated oil companies by reserves and output.

superposition

The stratigraphic principle that in an undisturbed succession each layer is younger than the one beneath it.

superposition in space

Summing the pressure effects of several wells at a point, to model how they interfere with one another.

superposition in time

Summing the pressure responses of successive rate changes at one well, each starting when its change occurred.

supersaturated solution

A solution that contains more dissolved solute than it should be able to hold at a given temperature and pressure.

supervised learning

Machine learning in which the model is trained on examples whose correct answers are already known.

supervisor

The person assigned to complete a Supervisor Assessment. This may be the employee's actual supervisor or manager, a team leader, a senior position holder, a third-party from a different business unit or another competent person.

supervisor assessment (SA)

A supervisor completes an online Assessment of each of his personnel based on long-term observation of job performance using CMS Online software.

supervisory personnel

The people accountable for authorizing and overseeing work.

supplied respirator

A respirator fed clean air from outside the work area, needed where filtration cannot protect.

supplier appraisal

Assessing a supplier's capability and standing before or during engagement.

supplier diversity

Deliberately sourcing from businesses owned by under-represented groups.

supplier performance

How well a supplier actually delivers against quality, time and cost commitments.

Supplier Relationship Management (SRM)

Managing key suppliers as ongoing relationships rather than transaction by transaction.

supplier selection criteria

The stated basis on which suppliers are compared and chosen.

supply and demand balance

The running comparison of production against consumption that sets the direction of price.

supply base

The set of suppliers an organization actually uses.

supply chain disruption

An event that interrupts flow, whose cost usually exceeds the savings that created the exposure.

supply chain integration

Coordinating across organizations so the chain behaves as one system.

supply chain loss

The difference between volumes shipped and received, from evaporation, clingage and measurement error.

supply chain management

Coordinating the flow of goods, information and money from supplier to end customer.

supply chain risk

Exposure to disruption anywhere in the chain, including at suppliers' suppliers.

supply current

The current into the VCC+/VDD+ or VCC-/VDD- terminal of the op-amp while it is operating.

supply current (shutdown)

The current into the VCC+/VDD+ or VCC-/VDD- terminal of the amplifier while it is turned off.

supply management

The wider discipline of managing supply markets, not just placing orders.

supply vessel

A boat that carries equipment, consumables and personnel between shore and an offshore installation.

supply voltage

Bias voltage applied to the op amp power supply pin(s), usually specified as a ± value referenced to network ground.

support bracket

A bracket carrying the weight of piping or equipment.

support competencies

Competencies that identify the underlying basic knowledge, skills and experiences that an individual must have to undertake the Core Competencies to the required level. Included are those secondary and nonroutine competencies expected in defined job duties (competencies necessary to function effectively in a position, but the CUs would not be to the depth and detail of a Functional Core CU).

suppression

The deliberate reduction of unwanted amplitudes in seismic acquisition or processing.

suppressor

A device limiting a voltage surge or radio interference.

supratidal

Above normal high tide, flooded only by storms, and where evaporites form.

surface area

The amount of exposed surface between things. Usually expressed in square inches.

surface casing

The casing string set through the shallow section to protect fresh water and provide a base for well control equipment.

surface interest

Ownership of the surface of a tract, separate from ownership of the minerals beneath it.

surface pipe

Another term for surface casing, the shallow string that anchors the wellhead.

surface pressure

Pressure measured at the wellhead or in the surface equipment rather than downhole.

surface production facilities

The separators, treaters, compressors and tanks that process production before export.

surface seismic

Seismic recorded at surface, the standard method as against borehole measurements.

surface shut-in

Closing a well at the wellhead so that the tubing and casing hold the full shut-in pressure.

surface tension

The contractive tendency of the surface of a liquid that allows it to resist an external force, caused by the attraction of particles in the surface layer by the bulk of the liquid, which tends to minimize surface area. Surface tension applies to a single liquid surface, whereas interfacial tension applies to the interface of two immiscible liquids.

surface tension forces

A contractive tendency of the surface of a liquid that allows it to resist an external force.

surface wave

A wave that travels along an interface, its energy confined near the surface rather than spreading through the volume.

surface-controlled subsurface safety valve (SCSSV)

A downhole safety valve held open by hydraulic pressure from a control line run outside the tubing, abbreviated SCSSV.

surfactant

A molecule with a water-soluble and an oil-soluble end, which concentrates at interfaces and lowers the tension across them.

surfactant flooding

An enhanced recovery process in which surfactant is injected to cut interfacial tension and free trapped residual oil.

surfactant-alternating gas

An enhanced recovery scheme injecting alternating slugs of surfactant solution and gas, abbreviated SAG.

surfactants

Chemicals that lower interfacial tension, used to free trapped oil and to stabilize or break emulsions.

surge

A sudden rise in pressure caused by a rapid change in fluid velocity.

surge device

In a differential relay, a device that blocks small amounts of fault current, but allows heavy amounts of fault current to flow through the relay's current coil.

surge reliever

A fast-acting relief valve that opens on a pressure surge in a liquid pipeline.

surge suppressors

Electrical components typically applied to contactors, relays, and solenoids to prevent induced voltages from disturbing nearby drive components.

surge tank

A vessel or tank that provides the capacity for handling surges in the volume of flow between process units, or for storing dry glycol.

surging

The rapid flow of gas back and forth through a centrifugal compressor.

surrounding bed

The formation above or below the bed a logging tool is reading, whose properties leak into the measurement.

survey

A set of measurements made and recorded over a defined area or along a defined path.

surveying technique

The method used to determine wellbore or surface position.

suspended particle

A solid held in a fluid without dissolving.

suspended solids

Dust and other solid particles that contaminate the water in a cooling tower.

suspended well

A suspended well is one which used to produce hydrocarbons from a reservoir and at which operations have ceased and will not resume for a period of time, often at least 30 days.

sustainability

Meeting present needs without compromising the ability of others to meet theirs.

sustainability report

The annual account of environmental and social performance published alongside the financials.

sustainable development

Meeting present needs without foreclosing the ability of later generations to meet theirs.

sustainable management

Running an organization with long-term environmental and social effects in view.

sustainable marketing

Marketing that accounts for long-term social and environmental effect, not just the sale.

sustainable procurement

Buying in a way that accounts for environmental and social impact alongside price.

sustainable sourcing

Buying with regard to environmental and social impact across the supply chain.

sustaining change

Making a change permanent after the attention and the project team have moved on.

SV-wave

A shear wave polarized so that its particle motion lies in the vertical plane containing the direction of travel.

swab

To lower wellbore pressure by dragging fluid up with pipe, a tool or a cupped seal being pulled out.

swab valve

The valve on top of the Christmas tree that gives vertical access into the well for wireline and coiled tubing.

swabbing

Reducing wellbore pressure by pulling pipe too quickly, drawing formation fluid in.

swage

A tapered solid tool driven through tubing to push a collapsed or restricted section back to full internal diameter.

swaging tool

A tapered slickline tool driven through collapsed or deformed tubing to push it back to round.

swamp

A wetland with standing or intermittent water supporting trees and woody plants.

swap

An agreement to exchange a floating price for a fixed one over a defined period.

swap contract

An agreement to exchange a floating price for a fixed one over a period.

swash bar

Swash bars are built by wave-induced accumulations of sand in the distal portions of ebb deltas and move onshore.

swath

The strip of ground covered in one pass of a seismic acquisition.

sweep

One horizontal pass of an oscilloscope's electron beam from left to right across the screen.

sweep efficiency

The fraction of the reservoir volume actually contacted by an injected fluid.

sweep pill

A small volume of viscous fluid circulated to pick up debris or residual fluid from the hole or the surface system.

sweep speed

For an analog oscilloscope, an indication of how fast the Dace can sweep across the screen, allowing you to see fine details. The fastest sweep speed of an oscilloscope is usually given in nanoseconds/div.

sweet

Said of oil or gas containing little or no hydrogen sulfide or other sulfur compounds.

sweet corrosion

Corrosion driven by carbon dioxide dissolved in water, forming carbonic acid, with no hydrogen sulfide involved.

sweet crude

Generally, a crude oil whose sulfur content is less than 1%.

sweet crude oil

Crude with sulfur content below about 0.5 to 0.7 percent by weight.

sweet gas

Natural gas containing little or no acid gases (hydrogen sulfide or CO2).

sweet gas specification

The sulfur limit gas must meet to be called sweet and sold.

sweet spot

The part of a play or reservoir expected to produce best.

sweetening

The process of removing sour contaminants (acid gases or sulfur compounds) from natural gas to improve odor or color.

sweetening unit

The plant section removing acid gases so the product meets sulfur specification.

swell

A temporary rise in boiler drum level caused by changes in steam flow.

swellable

Expanding on contact with water or oil, used in self-setting annular seals.

swellable packer

A packer whose elastomer sleeve swells on contact with oil or water downhole, sealing the annulus without any setting mechanism.

swing check valve

A check valve that has a hinged disc that swings open to allow fluid to flow through the valve.

swiss cheese model

The image of layered defenses each with holes, an accident happening when the holes line up.

switch

A device that can be opened or closed to start or stop current flow in a circuit.

switch rack

Equipment that routes electricity to pump slabs and pits; also called a motor control center.

switchboard

The electrical distribution panel supplying rig or platform equipment.

switched feedback resistance amplifier

An inverting amplifier with two or more resistors in its feedback path that are switched into the feedback path by a switching device.

switchgear

The assembly of breakers and busbars distributing and protecting electrical supply.

switchgear assembly

An assembly of circuit breakers and related components that are housed in a single enclosure.

switchyard

A facility that connects generators to transmission lines or connects transmission lines together.

swivel

A component that helps prevent wire rope from transferring its normal twisting motion to the load being lifted.

swivel flange

A two-part flange whose bolt ring turns independently of the hub, so bolt holes can be aligned without rotating the pipe.

SWOT analysis

Setting internal strengths and weaknesses against external opportunities and threats.

SWR

Synthetic/water ratio — the proportion of synthetic base fluid to water in the liquid phase of a synthetic mud.

symbol

A name given to a device in a ladder diagram (synonym for alias, tag, or label). Also, a small picture used to represent a component in an electrical system.

symmetric vs. asymmetric cryptography

One shared key against a public and private key pair.

syn

Abbreviation for synthetic, most often for synthetic-base drilling fluid.

synchronous inputs

Are normal data inputs J and K to a flip-flop that has effect on the outputs Q and Q-NOT only in step, or in sync, with the clock signal transitions.

syncline

A downward-convex fold in which the youngest beds lie at the core.

syndepositional

Occurring at the same time as deposition.

syngas

A hydrogen and carbon monoxide mixture from reforming or gasification, feedstock for fuels and chemicals.

synrift

Deposited while rifting was active, so beds thicken toward the controlling fault.

synsedimentary

A fault or fold that forms or grows within a sediment during sedimentation.

synthesis gas

A mixture of hydrogen and carbon monoxide, the intermediate in gas-to-liquids and ammonia.

synthetic data

Data generated by computation from a model rather than recorded from the physical world.

synthetic fault

A subsidiary fault dipping in the same direction and with the same sense of throw as the master fault it accompanies.

synthetic natural gas

Methane-rich gas manufactured from coal or heavy hydrocarbons rather than produced from a reservoir, abbreviated SNG.

synthetic seismic

Modelled seismic data computed from an earth model.

synthetic seismogram

A direct one-dimensional model of acoustic energy traveling through the layers of the Earth, generated by calculating reflection coefficients from sonic and density logs and applying a wavelet. Usually generated to compare with actual seismic data and identify reflectors with known formations.

synthetic seismograms

Seismic traces computed from a well's sonic and density logs to predict what the surface seismic should show there.

synthetic-base fluid

A drilling fluid built on a manufactured base liquid such as an olefin or ester, of known composition rather than refined from crude.

synthetic-base mud

An invert-emulsion mud whose continuous phase is a manufactured base fluid rather than a refined oil.

synthetic/brine ratio

The volume ratio of synthetic base fluid to brine in a synthetic-base mud.

synthetic/water ratio

The proportion of synthetic base fluid to water in the liquid phase of a synthetic mud, abbreviated S/W.

syphilis

A chronic infectious disease, caused by a bacteria, that affects the genitals, skin, mucous membranes, aorta, brain, liver, bones and nerves. It is usually transmitted during sexual intercourse, but often passed on to an unborn child.

system

A group of equipment that works together to process materials.

system diagram

A drawing showing how a system's components connect.

system factors

The structures, processes and incentives that will either sustain a change or undo it.

system identification number

A number assigned to the components in a process control system to identify the system to which the components belong.

system leverage point

The place in a system where a small change produces a disproportionate effect.

system piping

The pipework belonging to a system.

system prefix

A prefix that identifies which plant system a component belongs to.

system tract

A package of strata deposited during one part of a sea-level cycle.

systematic decision-making model

A defined sequence for making a decision, used to avoid deciding by impression.

systematic error

An error that keeps the same sign and magnitude, so it accumulates instead of averaging out.

systems thinking

Seeing a problem as part of an interacting whole rather than as an isolated fault.

systems tract

A subdivision of a depositional sequence, bounded by sequence stratigraphic surfaces and deposited during one segment of the relative sea level cycle.