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Discover the IHRDC Energy Glossarybeta

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T

T 1

Longitudinal relaxation time — how long excited protons take to realign with the static magnetic field in an NMR measurement.

T 2

Transverse relaxation time — the decay of the in-plane NMR signal, faster in small pores than in large ones.

T-account

The simple two-sided representation of an account, used to work out entries.

table

A type of chart used in the NEC to provide detailed information explaining code content.

tachometer

A feedback device in which a rotor shaft generates a voltage indicating its speed; commonly called a tach.

tadpole

The dipmeter plot symbol whose position gives dip angle and whose tail points in the dip direction.

tag

The name given to a device to identify it in a ladder diagram; synonym for alias, label, or symbol.

tag line

A tine, often made of fiber rope, that is used to help prevent a load from swaying or spinning during a lift and to help guide the load to its final position.

tag number

The identification number assigned to a specific process instrument or field device, often tied to a process loop or plant location.

tagout

A procedure that uses tags on points of control to warn personnel, employees, and contractors not to operate equipment or activate switches and valves.

tail

The closing pages of a log print, carrying the well data, recording parameters and calibration records.

tail buoy

The surface float marking the far end of a towed streamer.

tail cement

The denser, higher-strength slurry pumped last in a primary job, so it ends up around the shoe.

tail gas

Leftover gas that leaves the catalytic reaction section of a sulfur recovery unit.

tail mute

A cutoff applied at the far-offset, late-time end of a gather to remove noise that stacking would otherwise carry.

tail pipe

The tubulars and equipment run below the production packer, into the perforated interval.

tailoring

Adapting a methodology to the project rather than applying it wholesale.

Taitel–Dukler

The 1980 mechanistic model predicting which flow regime forms in vertical two-phase flow, from the physics of each transition.

take-off

The removal of either overhead product or bottoms product from a distillation system.

take-or-pay

An obligation to pay for contracted volume whether or not it is lifted.

take-up

A value used to determine where to start a conduit bend.

talent acquisition

The end-to-end work of attracting and hiring people, wider than recruitment alone.

talent acquisition process

The defined sequence from workforce plan through sourcing and selection to accepted offer.

talent management system

The software holding recruitment, performance and development records together.

talent pipeline

A maintained pool of potential candidates, built before the vacancy exists.

talent supply chain

Treating the flow of people into and through roles as a supply problem to be managed.

tall oil

A by-product of wood pulping, rich in fatty and resin acids, used as a raw material for oilfield emulsifiers.

tally

The measured record of every tubular run into or pulled out of the well, with its length and position in the string.

talus

Talus forms when rocks are weathered and erode from a cliff or steep slope. The resulting debris, which can include anything from small pebbles to large boulders, accumulates at the base of the cliff or slope.

TAME

Thermally activated mud emulsion — the use of a cloud point glycol that comes out of solution at temperature and seals the shale it contacts.

tangent

A trigonometric function expressing the ratio between the lengths of the opposite and adjacent sides of a right triangle.

tangential

Relating to a line or direction perpendicular to the radial direction.

tangential wave

A shear wave, in which particle motion is perpendicular to the direction of travel.

tank

A vessel for storing or measuring liquid.

tank battery

A system of two or more storage tanks located together at the same facility, connected by pipelines and used to store produced water, natural gas, and crude oil.

tank bottoms

The settlings in the bottom of a lease tank.

tank calibration

Measuring a tank's dimensions and building the table that converts liquid level into volume.

tank circuit

A tuned circuit in which current flow changes direction as a result of the charging and discharging of a capacitor and the expanding and collapsing of a magnetic field around a coil.

tank dike

A bund wall built around a storage tank to contain the contents if the tank fails.

tank farm

A collection of storage tanks in one area of a facility.

tank reactor

A stirred vessel in which reaction occurs, as distinct from a tubular reactor.

tank rental

The cost of leasing storage, central to whether a contango play pays.

tank table

A table giving barrels of oil for any depth of oil in a lease tank.

tankage

The total storage capacity of the tanks serving a field or facility.

tanker

A ship built to carry liquid cargo in bulk — crude, products, LPG or LNG.

tanker agreement

The contract governing carriage of a cargo by tanker, whether charter or contract of affreightment.

tanker capacity

The cargo a vessel or fleet can carry.

tanker demand

The requirement for tanker capacity, which with supply sets freight rates.

tanker fleet

The total tonnage available to move crude and products.

tanker size

The vessel class, which determines cargo capacity and port access.

tanker truck

The road vehicle distributing fuel from terminal to retail outlet.

tankerman

An operator who is trained and certified to work on barges and handle marine vapor recovery equipment.

tannic acid

The polyphenolic acid extracted from tannins such as quebracho, used as a mud thinner.

tannin

A tree bark extract used as a deflocculant in high-pH water-base muds.

tannins

Plant-derived thinners used to reduce drilling fluid viscosity.

tap

A connection at some point between the ends of a winding.

taper gauge

A wedge-shaped gauge used to measure spaces between parallel surfaces. Also called a wedge gauge.

taper tap

A tapered, threaded fishing tool screwed into the bore of a hollow fish to grip it.

tapered cutoff

An NMR processing choice that grades the split between bound and free water across a range of T2 rather than at a single value.

tapered string

A string made up of two or more sizes or weights of pipe, heaviest where the load is greatest.

tar sand

Sand whose pore space is filled with bitumen or heavily degraded oil that has lost its light ends.

tar sands

More technically called bituminous sands, a type of unconventional petroleum deposit.

tare weight

The empty weight of a vessel or the weight of a vessel with all air re¬moved.

target formation

The specific rock unit a well is drilled to reach and test.

target market

The specific group a product is aimed at.

target octane

The desired octane number for a product.

target organ effect

The characteristic of a hazardous substance that causes it to affect a specific organ.

target organ hazards

Chemicals that target and create effects in specific body organs, including the liver, the kidneys, and the nervous system.

target temperature range

A temperature range including the temperature at which a fraction is separated.

task list

The enumerated activities to be performed.

task management

Tracking discrete pieces of work through to completion.

tattletale light

A local indicator lamp showing a device has operated, so a passing operator can see it without instruments.

tau

Tau is the neutron decay time (in microseconds).

tax law

The rules determining what is taxable, when, and at what rate.

tax-and-royalty regime

A fiscal system in which the state takes a royalty on production plus tax on profit.

taxes, duties and quotas

The fiscal and quantitative measures applied to goods crossing a border.

Taylor bubbles

The large bullet-shaped gas bubbles, nearly filling the pipe, that characterize slug flow.

TC

The abbreviation often used to represent time constant.

TCF

Trillion cubic feet; a unit of measurement for natural gas volumes.

TCFD (Task Force on Climate-related Financial Disclosures)

The disclosure framework asking companies to report climate risk in financial terms.

TCP

Tubing-conveyed perforating: running perforating guns on tubing, drillpipe or coiled tubing rather than on wireline.

TCP/IP

Transmission Control Protocol/Internet Protocol. A common communication protocol used to configure networks on Ethernet and on the Internet.

TCP/IP model

The four-layer model that actually underlies the internet.

TD

Total depth — the deepest point reached by the well.

TDA

TDA - time domain analysis.

TDEM

Time domain electromagnetic method — an EM survey using switched current pulses and measuring the decaying secondary field afterwards.

TE

Transverse electric — the electromagnetic mode with the electric field entirely perpendicular to the direction of propagation.

team assignment

Work given to a small group, used to force discussion rather than individual recall.

team building

Deliberate work to improve how a team functions together.

team cohesion

The strength of members' commitment to the team and to each other.

team dynamics

How a group's roles, trust and conflict determine whether it performs.

team room

A dedicated space where a team works together and its information is displayed.

team types

The recognized forms — functional, cross-functional, project, virtual — each with different demands.

team vs. group

A team shares a goal and depends on each other; a group merely shares a manager or a room.

techlog

Techlog is a Schlumberger owned Windows based software platform intended to aggregate all the wellbore information. It allows the user to interpret any log and core data.

technical data

Data collected from seismic surveys and the drilling of wells together with their technical interpretation.

technical document

A document whose purpose is to specify, instruct or record technical matter.

technical evaluation agreement (TEA)

An agreement letting a company evaluate a concession's geological and engineering data, usually with a right to negotiate afterwards, abbreviated TEA.

technical writing

Writing that conveys technical information accurately to a defined audience.

technology mapping

Matching available technologies to the business problems each could actually address.

tectonic

Relating to the structure of the Earth's crust and the large-scale processes that control its properties and evolution over geological time.

tectonic environment

The setting of an area relative to plate boundaries and the deformation those boundaries produce.

tectonic event

A tectonic event is a physical occurrence resulting from the movement of the Earth's crust.

tectonic history

The sequence of deformation a region has experienced.

tectonic setting

The plate-scale situation a basin sits in, which predicts its shape, fill and heat flow.

tectonic stress

Stress imposed by plate motion rather than by overburden weight.

tectonic subsidence

Sinking driven by lithospheric processes rather than by sediment load.

tectonics

Tectonics is concerned with the processes which control the structure and properties of the Earth's crust, and its evolution through time.

tectonics and structure

Tectonics is concerned with the processes which control the structure and properties of the Earth's crust, and its evolution through time.

tectonism

Deformation of the crust by plate tectonic forces.

teflon

A fluoropolymer used for seals and seats where chemical resistance and low friction matter.

telemetry

The highly automated communications process by which measurements are made and other data collected at remote or inaccessible points and transmitted to receiving equipment for monitoring and usage.

telemetry system

The means of getting downhole measurements to surface.

telescoping

Extending or retracting by sliding sections, as a derrick or a joint.

telescoping gauge

A non-graduated precision measurement tool used to measure inside diameters and the distances between parallel surfaces. Also called a snap gauge.

televiewer

A tool imaging the borehole wall acoustically.

tell-tale

An indicator that makes the position or state of a hidden mechanical component visible from outside.

telluric current

A natural low-frequency electric current flowing through the Earth's crust, driven by variations in the external magnetic field.

telluric-current method

A survey comparing natural earth currents measured at a roving station against those at a fixed base station.

temperature

The degree of hotness or coldness of a substance, as measured on a scale; the average molecular kinetic energy of a substance.

temperature compensator

Device correcting a measured volume to reference temperature, since a liquid's volume changes with heat.

temperature control valve

Valve modulating a heating or cooling medium to hold a measured temperature.

temperature controller

The instrument holding temperature, usually by modulating a heating or cooling medium.

temperature differential

The difference in temperature across an exchanger or between two points, the driving force for heat transfer.

temperature gauge

A local instrument showing temperature.

temperature gradient

The rate at which temperature rises with depth in the Earth, typically 1 to 2°F per 100 ft.

temperature indicator

The device showing temperature locally.

temperature log

A continuous record of borehole temperature against depth.

temperature measurement

Determining temperature, whose accuracy depends more on where the element sits than on the element itself.

temperature measurement device

The element sensing temperature, whose placement matters as much as its calibration.

temperature recorder

Instrument keeping a continuous temperature trace, the record a measurement dispute relies on.

temperature rise

The increase above ambient temperature of a transformer winding due to energizing and loading the transformer.

temperature sensor

The element converting temperature into a signal.

temperature separator

Vessel separating a chilled stream into gas and condensed liquid at a controlled low temperature.

temperature separator lts

The low-temperature separator, splitting gas and liquid at the coldest point in the train.

temperature stability

A fluid or additive's ability to keep its properties through prolonged exposure to heat.

temperature survey

A set of borehole temperature measurements run to locate cement tops, flow behind pipe or injection profiles.

temperature-compensated flow control valve

A flow control valve that compensates for system temperature changes by changing orifice size.

ten-minute gel strength

The shear stress needed to start a mud moving after it has stood undisturbed for ten minutes.

ten-second gel strength

The shear stress needed to start a mud moving after ten seconds at rest, measured by the API procedure.

tender evaluation criteria

The stated basis on which bids will be scored, fixed before bids are opened.

tender pack

The complete document set issued to bidders: scope, terms, forms and evaluation basis.

tendinitis

An inflammation of a tendon that causes soreness, pain and restriction of movement. Tendinitis usually results from repetitious, forceful exertions, oftentimes when there is an awkward posture like a bent wrist or reaching overhead. It commonly occurs at the wrist, elbow and shoulder.

tenosynovitis

Inflammation of the sheath within which a tendon slides back and forth. It usually occurs at the wrist and hand area and results in soreness, pain and a reduction of movement.

tensile

Relating to pulling stress, which determines how much load a string can carry.

tensile strength

The stress a material can carry in tension before it parts.

tensile stress

Stress pulling material apart, which rock resists poorly and which opens fractures.

tension device

A tension device measures strain on the logging cable.

tension fracture

A tension fracture is the result of tensional stress in a rock.

tension load

The load (or force) on the piston rod as it travels toward the crank end of the cylinder.

tension loaded disc

A pressure relief device that ruptures when pressure under the dome of the disc exceeds the disc design strength.

tension loading

The forces acting on a sucker rod during the upstroke because of the weight of the rods below it plus the weight of the fluid being lifted. Tension loading causes the rod to stretch along its vertical axis.

tension release

Physical techniques for discharging the tension that otherwise shows in delivery.

tension-set packer

A packer set by pulling up on the running string, which compresses the element from below.

tensional

Relating to stretching stress, which produces normal faults.

tensioning

Applying controlled tension, as to a belt or bolt.

tensioning device

The component applying and holding tension in a belt or chain.

tensor

A tensor method is a mathematical entity with components that change in a particular way in a transformation from one coordinate system to another. Tensor methods are used in "upscaling" reservoir parameters for use in reservoir simulation studies.

tensor methods

Analysis using tensors — quantities whose components transform in a defined way between coordinate systems.

tent card

The folded name card on the table, and a standing item on every program's print list.

TEOR

Thermal enhanced oil recovery — recovery processes that add heat to the reservoir to reduce oil viscosity.

term lease

An oil and gas lease that ends on a fixed date whether or not production has been established.

term sheet

The outline of principal commercial terms agreed before full documentation is drafted.

term sheet projections

The financial forecasts accompanying a term sheet, which the eventual covenants are set against.

terminal

A component that forms the end of an electrical circuit.

terminal lugs

Certain types of larger terminals.

terminal stud

The screw or bolt used to attach a terminal to a device.

terminal temperature difference (TTD)

The difference between a feedwater heater's feedwater outlet temperature and the saturation temperature of the steam in the condensing section.

terminating resistor

A resistor used to close a communications link.

termination

A connection between a conductor and a piece of electrical equipment.

ternary diagram

A triangular plot in which each point represents a mixture of three components summing to 100 percent.

terrain correction

A gravity correction for the pull of hills above and the missing mass of valleys below the station, both of which reduce the reading.

terrestrial

Pertaining to sediments deposited on land, above the reach of the tide.

terrigenous

Refers to materials, particularly sediments such as mud, clay, sand, gravel, volcanic materials, and boulders, that originate on land through weathering and erosion and are transported to marine or other depositional environments by rivers, wind, glaciers, or other processes.

terrigenous (clastic) sediment

Terrigenous sediments are sediments that come from land and are the most abundant type of sediment. They are created when rocks on land are eroded by wind, rivers, and volcanism, and are then transported by waterways.

terrigenous sediments

Terrigenous sediments are derived from eroded rocks on land (including mud, clay, sand, gravel, volcanic materials and boulders) and are transported by rivers to the sea where they are deposited on continental slopes, shores or shelves.

tertiary recovery

Tertiary recovery, or enhanced oil recovery (EOR), is a process for extracting oil that has not already been retrieved through the primary or secondary oil recovery techniques.

test separator

A small separator used to isolate one well's production and meter its oil, gas and water.

testing

The process by which the hazards that may confront entrants of a permit space are identified and evaluated. Testing includes specifying the tests that are to be performed in the permit space.

tests

In this context, a test is the term for a foraminifera's shell. Foraminifera are a group of single-celled organisms that build a shell-like structure called a test, which is typically made of calcium carbonate or other materials.

Tethyan trend

The Tethyan Trend refers to an expansive area of fold belts that range from Western Europe to the Australian coast. Formation of this area began with the separation of Eurasia from Gondwana in post-Paleozoic times, resulting in the creation of the Tethys Ocean. Subsequent convergence and collision of the Africa and Eurasia tectonic plates, which began at the start of the Late Cretaceous, caused subsequent uplift and folding. Additional plate convergences of the Philippine, Pacific and Australia plates caused additional deformation in this area (De Graciansky et al., 2011).

tetrahedral layer

The sheet of linked SiO4 tetrahedra that pairs with an octahedral sheet to build a clay mineral.

tetrahedral sheet

The silica layer in clay mineral structure, paired with the octahedral sheet.

Texas deck

The deck immediately below the drill floor on a jackup, from which the BOP stack and wellhead are accessed.

textural

Relating to grain size, shape and packing, which control porosity and permeability.

textural maturity

How far transport has sorted and rounded the grains, which predicts reservoir quality.

texture

In geology, texture refers to the size, shape and arrangement of the grains, crystals or particles within a rock or soil.

TFNB

Trip for new bit — the drilling report notation for a round trip made to change the bit.

TG

Trip gas — the slug of gas returned after a trip, from swabbing and from the time spent without circulation.

THAI

Toe-to-heel air injection: in-situ combustion using stacked horizontal wells, so combustion products and heated oil drain almost immediately into the producer below.

thalweg

Thalweg is the line of lowest elevation within a river valley or water course.

THD

Total Harmonic Distortion. A measure of the extent to which an electrical system's current draw is out of phase with the applied voltage.

the hydraulic principle

The principle that pressure applied to a confined fluid is transmitted throughout the fluid and the confining vessel or system.

theoretical

Derived from principle and equation rather than from measurement.

thereon

On that thing already named.

thereto

To that thing already named.

thermal alteration

Change in organic matter or mineralogy caused by heating.

thermal capture

The absorption of a slowed neutron by a nucleus, which then emits gamma rays as it settles back to its ground state.

thermal conductivity

A measurement of how easily heat is conducted through a substance; the ability of a substance to conduct heat.

thermal conductivity cell

A detector inferring composition from how readily the sample conducts heat.

thermal decay time log

A thermal decay time log is a record of the rate of capture of thermal neutrons in a formation after it is bombarded with a burst of neutrons.

thermal decay time logging tools

Thermal Decay Time (TDT) tools are Schlumberger's early series of pulsed neutron capture logging tools.

thermal decomposition

Breaking down the chemical composition of glycol due to high temperature.

thermal degradation

A condition in which the temperatures used for distillation degrade, or decompose, the feed.

thermal diffusion length

The average distance a thermal neutron travels while diffusing before it is captured.

thermal energy

A form of energy related to the amount of heat in a fluid that can be stored or transferred.

thermal energy unit

A unit of heat, the basis on which gas is bought and sold.

thermal expansion

The expansion of a liquid that occurs when temperature increases.

thermal gradient

The rate at which temperature increases with depth, also called the geothermal gradient.

thermal growth

The dimensional change of a machine as it reaches operating temperature, allowed for in cold alignment.

thermal history

The temperature a rock has experienced through time, which fixes its maturity.

thermal maturation

The heat-driven conversion of organic matter to oil and then gas.

thermal maturity

How far a source rock has been taken through the heating that converts kerogen into oil and gas.

thermal neutron

A neutron slowed to thermal energy, whose capture rate is what a neutron log responds to.

thermal neutron absorber

An element with a large cross section for capturing slow neutrons.

thermal neutron porosity

Thermal neutron porosity tools measure the slowing down and capture of neutrons between a source and one, or more, thermal neutron detectors.

thermal neutron porosity measurement

The thermal neutron porosity is a measurement of the slowing down and capture of neutrons between a source and one, or more, thermal neutron detectors. The neutron source emits high energy neutrons that are slowed mainly by elastic scattering to near thermal levels. Thermal neutrons have about the same energy as the surrounding matter, typically less than 0.4 eV. The slowing down process is dominated by hydrogen.

thermal neutrons

Free neutrons whose energies have a Maxwell–Boltzmann distribution with kT = 0.0253 eV (4.0 × 10⁻²¹ J) at room temperature.

thermal overload

A protective device tripping on the heating effect of sustained excess current.

thermal overload device

A type of overload device that operates on the heat generated by current.

thermal reaction section

The section of a sulfur recovery unit in which H2S is burned to produce SO2 and some sulfur is condensed and removed.

thermal recovery

Any recovery process that adds heat to the reservoir to cut oil viscosity and improve its mobility.

thermal simulation

Reservoir simulation that solves an energy balance alongside the flow equations, so heat transport is modeled.

thermal subsidence

Sinking as stretched lithosphere cools and contracts, which fills a rift basin after rifting stops.

thermal unit

A unit of heat energy, the basis on which gas is bought and sold.

thermally activated mud emulsion

A glycol mud in which the glycol comes out of solution above its cloud point and deposits on the hot shale face.

thermistor

A temperature transducer that may be used as a temperature compensator in a measurement circuit.

thermochemical

Driven by heat rather than electricity, the route most high-temperature hydrogen processes take.

thermocouple

A temperature measurement device consisting primarily of two wires of dissimilar metals that produce a small voltage proportional to temperature.

thermocouple thermometer

A device that may be used to check the temperature of bearings in rotating equipment.

thermodynamic

Concerning heat, work and their conversion.

thermometer

A device or instrument used to measure and indicate temperature.

thermoplastics

Polymers that soften on heating, the largest class of petrochemical products.

thermosiphon

A type of reboiler in which the process vapor and liquid are not separated before leaving the reboiler. Flow through the unit is created by a difference in densities.

thermosiphon reboiler

A type of reboiler in which the process vapour and liquid are not separated before leaving the reboiler. Flow through the unit is created by a difference in densities.

thermostat

A pilot device that responds to temperature changes based on set point.

thermostatic

Acting on temperature to hold it constant.

thermowell

A closed tube in a vessel wall holding a temperature element, so it can be withdrawn without opening the process.

thicken

To increase viscosity, deliberately or through contamination.

thickener

A vessel concentrating settled solids into a denser sludge.

thickeners

Additives that raise viscosity, used in fracturing and drilling fluids.

thickening time

How long a cement slurry stays pumpable under downhole conditions, measured on a consistometer.

thickest

The greatest thickness in a mapped interval.

thief

A device that is pushed down into solid materials to obtain samples, or lowered into a lease tank to collect an oil sample for testing.

thief hatch

The small hinged opening on top of a lease tank through which the gauger looks in, gauges the level and takes samples.

thief zone

A permeable or fractured interval that takes drilling fluid away from the wellbore.

thief zones

A formation encountered during drilling into which circulating fluids can be lost.

thimble

A metal insert that is placed inside a loop of wire rope to prevent kinking and deformation of the loop.

thin section, petrographic thin section

A thin section, or petrographic thin section, is a laboratory preparation of a rock or mineral sample for use with a polarizing petrographic microscope, electron microscope and electron microprobe.

thinner

An additive that lowers a mud's viscosity by dispersing the clay platelets that are holding it together.

third-party logistics (3PL)

Outsourcing warehousing and transport to a specialist provider.

thirty-two-bit word

A digital expression of 32 bits; for example, 0100 0111 0100 0111 0100 0111 0100 0111.

thixotropic

Said of a fluid that gels when left still and thins again when stirred, reversibly.

thixotropy

The reversible development of gel strength in a fluid at rest, and its breakdown under shear.

Thomas-Kilmann conflict mode instrument

The assessment placing a person's conflict style on assertiveness and cooperativeness.

thomsen

The parameters describing weak seismic anisotropy in layered rock.

thorium

A chemical element with symbol Th and atomic number 90. A radioactive actinide metal, thorium is one of only four radioactive elements that still occur in quantity in nature as a primordial element. In sedimentary rocks, thorium is essentially resistate in character, as its major host minerals (monazite and zircon) are highly resistant to both chemical and physical breakdown. Because it is radioactive, thorium is identified in gamma ray logging tools, useful for correlating with offset wells during drilling.

thousand standard cubic feet per day

A gas rate unit, one thousand cubic feet per day at standard conditions, abbreviated Mcf/d.

thread protector

A cheap threaded cap or plug fitted over a connection to keep the threads undamaged in handling and transport.

thread rule

A pocket gauge used at the wellsite to identify or confirm a tubular's thread type and size.

threadform

The profile and geometry of a threaded connection, particularly a rotary shouldered one.

threading

A condition that Leaves fine tines on the surface of a commutator.

threat

Anything with the potential to cause harm to an asset.

threat actor

The person or group behind an attack, whose capability and motive shape the risk.

Threat and Vulnerability Assessment (TVA)

A structured review of security threats against a facility and the weaknesses they could exploit.

threat profile

The specific set of adversaries and methods a given facility realistically faces.

three levels of editing

Substantive, copy and proof editing, done in that order and not conflated.

Three Scorecards

The integration of the corporate, human resources and workforce scorecards into one line of sight.

three types of data analytics

Descriptive, predictive and prescriptive — what happened, what will, and what to do.

three-component (3C) seismic data

Data recorded with three orthogonal sensors at each station, capturing the full vector of ground motion, abbreviated 3C.

three-dimensional (3D) seismic data

A closely spaced grid of seismic lines processed as a volume, giving continuous spatial sampling of the subsurface.

three-dimensional (3D) survey

Acquisition on a grid of closely spaced source and receiver lines, giving continuous subsurface coverage rather than isolated sections.

three-dimensional seismic

Seismic recorded on a grid rather than along lines, giving a data volume that can be sliced any way.

three-phase

Separation into gas, oil and water.

three-phase alternating current

Three separate alternating currents that flow through three separate conductors.

three-phase flow

Simultaneous flow of oil, gas and water.

three-phase generator

A generator that has three sets of stator windings and produces three output voltages.

three-phase separation

Separating gas, oil, and water.

three-phase separator

A vessel that splits the wellstream into gas, oil and free water.

three-phase vertical

A vertical vessel arranged to split gas, oil and water.

three-phase vertical separator

Vertical vessel splitting gas, oil and water.

three-second rule

A defensive driving technique that keeps three seconds between vehicles and gives you enough time to react in the event of an unexpected event. When the vehicle in front of you passes a fixed object, you should be able to count to three seconds before your vehicle reaches the object.

three-way valve

A multiport valve with three ports.

threshold limit value (TLV)

The time-weighted average concentration for a normal eight-hour workday to which nearly all workers may be repeatedly exposed without adverse effect.

threshold velocity

The lowest fluid velocity at which a spinner will begin to turn.

throat bushing

A bushing at the end of a pump's stuffing box that prevents packing from being pushed out of the stuffing box into the suction eye of the impeller.

throttling

The regulation of fluid flow by positioning a flow control valve somewhere between fully open and fully closed. In compressors, partially opening the suction valve to control the volume of gas entering the cylinder, though this increases discharge temperature and horsepower requirements and is used only as a temporary control measure.

through-conduit

Said of a valve whose bore is smooth and unobstructed when fully open, so a pig or tool can pass through it.

through-flowline (TFL)

A method of servicing a subsea well by pumping tools down the flowline and back, without a vessel over the well, abbreviated TFL.

through-tubing

Pertaining to any operation carried out through the production tubing without pulling the completion.

through-tubing gun

A small-diameter perforating gun able to pass through the tubing and fire below it.

through-tubing perforating

Perforating with small guns run through the production tubing.

throughput capacity

The maximum a facility can process or move in a period.

thrust bearing

A bearing that prevents shaft movements in the same direction as the centerline of the shaft.

thrust belt

A zone of stacked thrust sheets, structurally complex and seismically hard to image.

thrust collar

The shoulder on a shaft transmitting axial load to the thrust bearing.

thrust fault

A reverse fault dipping 45 degrees or less, on which the hanging wall has ridden up and over the footwall under compression.

thrust sheet

A slab of rock carried over younger rock along a thrust fault.

thrust shoe

The pad carrying axial load in a thrust bearing.

thrusting

Compressional faulting that stacks older rock over younger.

thyristor

The thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material.

TI

Transverse isotropy — anisotropy with a single symmetry axis, properties being equal in every direction perpendicular to it.

tick mark

A mark recorded with logging-while-drilling data showing when each sample was taken.

ticket printer

The printer producing the custody transfer ticket at a metering station.

tidal current

Water movement driven by tides, which sorts and transports sediment on shelves.

tidal flat

A low-relief intertidal surface, laying down thin alternations of sand and mud.

tie

To match data from different sources at a common point so that one can be interpreted in terms of the other.

tie line

On a phase diagram, the line joining the compositions of two phases in equilibrium with each other.

tie wrap

A length of material, usually nylon, that has a self-locking device at one end.

tieback

Connecting a new well or completion into existing infrastructure rather than building afresh.

tieback liner

A casing string run from the top of an existing liner back to the wellhead after the liner has been set and cemented.

tieback packer

The sealing assembly at the top of a liner into which a tieback string stabs and seals.

tieback string

Another name for a tieback liner — casing run from a liner top back to the wellhead.

tight

A relatively impermeable reservoir rock formation that does not allow fluids to pass through easily, making hydrocarbon production extremely difficult.

tight emulsion

An emulsion which is difficult to break.

tight formation

A tight formation is a relatively impermeable reservoir rock from which hydrocarbon production is difficult.

tight gas

Natural gas produced from relatively impermeable rock. Getting tight gas out usually requires enhanced technology applications like hydraulic fracturing. The term is generally used for reservoirs other than shale.

tight hole

A section of hole where the drillstring meets resistance because the wellbore has narrowed.

tight oil

Oil produced from a low-permeability reservoir that needs hydraulic fracturing to flow at commercial rates.

tight rocks, tight

Tight rocks are those formations with lo permeability.

TIH

Transverse isotropy with a horizontal symmetry axis, the fabric produced by one set of aligned vertical fractures.

time after bit

The interval between the bit drilling a formation and a log being recorded across it.

time base

The interval in which a timer counts elapsed time.

time base accuracy

An indication of how accurately the horizontal system of an oscilloscope displays the timing of a signal; usually listed as a percentage error.

time charter

Hiring a ship for a period at a daily rate, with the charterer directing its employment.

time constant

The time between when a process variable begins to respond to a changed control output and when it has substantially re-stabilized. Also called lag.

time domain

The representation of a signal as amplitude against time, rather than against frequency.

time domain analysis

Analysis of data and mathematical calculations in reference to time.

time line

A drawn sequence of cash flows against periods, used to set up a valuation.

time log

A record of where hours actually went, usually revealing a gap from where they were thought to go.

time management

Directing one's own hours toward what matters rather than toward what arrives.

time migration

Migration that repositions reflections in time, valid where velocity varies vertically but not strongly across the section.

time series analysis

Analyzing observations ordered in time, where sequence itself carries information.

time slice

A horizontal cut through a 3D seismic volume at a constant arrival time.

time spread

The price difference between two delivery months, traded in its own right.

time to fill

The days from opening a vacancy to an accepted offer.

time value of money (TVM)

The principle that money now is worth more than the same sum later.

time-average equation

The relation converting sonic travel time to porosity by weighting matrix and fluid.

time-domain electromagnetic method

An electromagnetic survey using transient current pulses and measuring the decaying secondary field after each pulse is switched off, abbreviated TDEM.

time-lapse

Pertaining to measurements repeated over the same area at intervals, to detect what has changed.

time-lapse mode logging

Time-lapse mode logging is the repeated acquisition with the same well logging tool at designated time intervals. Systematic time-lapse pulsed neutron capture logging gives a dynamic picture of the reservoir saturation response to production and water injection operations.

time-lapse seismic data

Repeat seismic surveys over a producing field, differenced to show where fluids have moved or pressure has changed.

timed contacts

The contacts on a timer that become energized when the timer has timed out.

timed slug analysis

Measuring injection velocity from the time a slug of radioactive tracer takes to travel a known distance down the well.

timeout

A deliberate break to consult, reconsider or defuse.

timer

A time-delay relay.

timing relay

A relay that imposes a brief delay before sending signals that cause breakers to trip.

Tin Can API

The successor standard recording learning experiences wherever they occur, also called xAPI.

tip

The part of an oxy-fuel gas welding torch that supplies the oxygen and acetylene mixture to the flame. Also called a nozzle.

tire concept

A defensive driving technique that involves being able to see the bottom of the tires of the vehicle in front of you when you stop.

tissot

Co-author of the standard text on petroleum formation and occurrence.

title block

A block of information on a diagram that contains details such as the diagram's name, what system or unit it is for, an identification number, revision number, and other information.

titrate

To add a reagent of known strength to a sample until a color change or meter reading marks the reaction complete.

titration

A test that uses a chemical reaction to determine the concentration of a solution.

TIV

Transverse isotropy with a vertical symmetry axis, the fabric of horizontally layered shale.

TM

Transverse magnetic — the electromagnetic mode with the magnetic field entirely perpendicular to the direction of propagation.

TOC

Total organic carbon: the weight percent of organic carbon in a rock, and the first measure of its source potential.

toe

Toe refers to the bottom or base of a slope, specifically the point where the slope meets a flat structure, or the outermost margin of displaced material during a landslide.

toe to heel air injection

An in-situ combustion process in which a vertical injector burns toward the toe of a horizontal producer, sweeping oil along it, abbreviated THAI.

toeset and foreset dips

Foreset dips are characterized by a depositional angle ranging between 25° and 30°, but they can reach 40° if the sediment is sufficiently coarse. Toeset dips represent the transition between the steeply inclined foreset and the sub-horizontal bottomset beds.

token

In a language model, the unit of text a model reads and generates; more generally, a metered unit of service consumption.

toluene

An aromatic solvent used in chemicals and to dissolve asphaltene deposits.

tomographic

Reconstructing an image from measurements made along many crossing paths.

tomography

Imaging the interior of a volume by inverting many measurements that pass through it along different paths.

tongs

Large hinged wrenches used to make up and break out threaded connections in the string.

tongue

The part of a terminal that connects to the terminal stud.

tongue-and-groove flange

A flange with a raised area on one half that contains a groove into which the tongue from the opposite flange half fits.

tool joint

The thick threaded connection welded to each end of a joint of drillpipe.

tool string

The assembled set of downhole tools run together on one trip.

toolface

The angular orientation of a bent housing or deflection tool around the axis of the hole.

toolpusher

The drilling contractor's senior representative at the rig, in charge of the rig crew and equipment.

tooth contact

Where gear teeth touch, whose pattern shows whether the mesh is correct.

top drive

A device that turns the drill string, consisting of one or more motors connected with appropriate gearing to a short section of pipe called a quill, which may be screwed into a saver sub or the drill string itself. The top drive is suspended from the hook, so the rotary mechanism is free to travel up and down the derrick.

top entry

A valve or vessel design allowing the internals to be serviced from above without removing the body from the line.

top lease

A lease taken on acreage already covered by an existing lease, taking effect only if and when that lease expires.

top log interval

The shallowest depth at which the log readings are valid, at or below the top of the logged interval.

top reflux

Straight run gasoline from the accumulator that is pumped back into the top of an atmospheric tower.

top tray

The uppermost contacting tray in a column, where the leanest solvent meets the cleanest gas.

topographic features

The physical features of an area.

topographic map

A map showing the shape of the land surface by contours of elevation, along with drainage and cultural features.

tops

“Tops” or “picks” are the common name for the top surface of a geologic layer.

topset, topset beds

Topset beds are the nearly level layers of sediment deposited on the top of a delta.

topside

The processing and utility equipment above water on an offshore platform.

torch

The component of an oxy-fuel gas welding rig that mixes the oxygen and acetylene to create a flame.

torch soldering

A joining process for copper, where the tube and fitting are properly heated, and solder (a solid wire) touched to the joint melts and is drawn in between the tube and the fitting, sealing the joint.

tornado chart

A tornado chart is a plot representing the effect of invasion on resistivity measurements that have different depths of investigation. The plot assumes a step-profile model of invasion and determines true resistivity, flushed zone resistivity and diameter of invasion from ratios of deep, medium and shallow resistivity measurements.

torpedo

The termination that joins the wireline logging cable to the bridle or tool head, carrying both the load and the electrical connections.

torque

A force that produces, or tends to produce, rotation; the turning or twisting force applied to an object, such as a motor shaft.

torque flowmeter

A flowmeter that measures the torque a flowing fluid exerts on a restrained rotor, rather than the speed of a free one.

torque switch

A device used in a motor operator to limit the torque that develops in the gear train, cutting off current to the motor when the turning force reaches a preset limit.

torque tube

A linkage mechanism that provides a high pressure seal and a twisting, or torquing, action used to convey motions that result from changes in level.

torque tube displacer

A type of displacer mechanism that converts the slight vertical motion of a displacer, through a special mechanical linkage, into a rotational motion that can be used to move a suitable indicator or can be amplified into a proportional signal for a transmitter or controller.

torque wrench

A wrench applying a measured tightening torque.

torsional

Relating to twisting, the load that fails drillpipe in high-torque wells.

tort law

Liability for harm caused outside contract, such as negligence or nuisance.

tortuosity

Tortuosity is a measure of the geometric complexity of a porous medium. Tortuosity is a ratio that characterizes the convoluted pathways of fluid diffusion and electrical conduction through porous media.

tortuosity factor

The term in the saturation equation accounting for the winding path current takes through pores.

tortuosity of a rock formation

The severity of curvature and size of pore necks in the pore network of a rock formation.

total condenser

A condenser that condenses all of the vapors from a distillation tower.

total current into VCC+

Maximum current that can be supplied to the positive power terminal of the op-amp. Usually specified as an absolute maximum.

total depth (TD)

The final measured depth reached by the well.

total flow

The amount of fluid that has passed a designated point.

total hardness test

The titration measuring combined calcium and magnesium in a mud filtrate or in makeup water.

total harmonic distortion

The ratio of the RMS voltage of the first nine harmonics of the fundamental signal to the total RMS voltage at the output.

total organic carbon (TOC)

Total organic carbon (TOC) is the amount of organic carbon in a geological formation. TOC is significant to oil and gas exploration because in sedimentary rock, it is a direct indicator for the rock's potential as a source rock in a petroleum system.

total petroleum initially-in-place

The quantity of petroleum estimated to exist originally in the naturally occurring accumulations. It includes the estimated quantity of petroleum in known accumulations (before any production), together with the estimated quantities in yet to be discovered accumulations.

total porosity

All the pore space in a rock as a fraction of its bulk volume, connected or not.

total power dissipation

The total dc power supplied to the device less any power delivered from the device to a load.

total pressure

The sum of the static pressure and the velocity pressure in a fan system.

total quality management (TQM)

An approach making quality the responsibility of everyone rather than of an inspection function.

total recordable rate (TRR)

The total recordable rate is a measure of the rate of recordable cases, normalized per 100 workers per year. The factor is derived by multiplying the number of recordable injuries in a calendar year by 200,000 (100 employees working 2,000 hours per year) and dividing this value by the total man hours actually worked in the year.

total residual chlorine

The total amount of free chlorine that remains in a process stream after the stream has been treated with chlorine. Abbreviated as TRC.

total shareholder return (TSR)

Represents share price appreciation and dividends returned to shareholders over a period. It is calculated as follows: [(stock price at the end of the period) – (stock price at the start of the period) + (dividends paid during the calculation period) ÷ (stock price at the start of the period)].

total solids

The volume percent of a mud that is solid, taken as what the retort does not recover as liquid.

totalizer

Either a mechanical or electronic device which counts pulses.

tour

A drilling crew's work shift, conventionally pronounced tower.

township

A survey township is a geographic reference used to define property locations for deeds and grants.

toxic chemicals

Chemicals that are poisonous.

toxic vapor

Vapor able to poison at concentrations that may not be detectable by smell.

toxic workplace culture

A culture where fear, blame or incivility drive out capable people and suppress bad news.

toxicity

A reference to how poisonous, or toxic, a material is.

trace

The visible shapes drawn on an oscilloscope screen by the movement of an electron beam.

trace element

An element in a sample that has an average concentration of less than 100 parts per million measured in atomic count.

tracer

A chemical, radioactive, or other material placed in the borehole fluid and later detected to infer information about the borehole or the drilled formations.

tracer measurement

Timing an injected marker between two detectors to find fluid velocity in a producing or injecting well.

tracer-ejector measurement

A velocity measurement made by releasing a slug of radioactive tracer and timing its arrival at detectors below.

tracer-loss measurement

An injection profile derived from how much tracer disappears from the stream between successive depths.

traces

A trace is the seismic data recorded for one channel. Typically, this is the sum of the recordings of the receivers in a group, or, with wireless receiver units, a single receiver group.

track

One of the vertical columns of a log presentation, each carrying its own set of curves and scale.

traction

Traction is a process that moves larger sediment grains or rocks along a riverbed, shore or planar surface by rolling or sliding them. This usually involves moderate to high water or wind velocity.

tractor trailer

The road vehicle combination used to move rigs and bulk product.

tractor, well tractor

A well tractor is an e-line, self-propelled robotic device used in highly deviated wells to drive tools down towards the toe of wellbores.

tractor, wireline tractor

Tractors are electrical tools used to push the tool string into hole, overcoming wireline's disadvantage of being gravity dependent. These are used for in highly deviated and horizontal wells where gravity is insufficient, even with roller stem. They push against the side of the wellbore either through the use of wheels or through a wormlike motion.

tractor, wireline tractor conveyance

A tractor is a device for assisting a wireline logging tool to descend a deviated or irregular profile wellbore.

trade agreement

A treaty setting the terms on which countries trade with each other.

trade convention

An international agreement standardizing how a trade matter is treated.

trade documentation

The paperwork without which goods do not clear customs or payment is not released.

trading book

The full set of a desk's open positions, physical and paper, viewed as one exposure.

trading counterparty

The other party to a trade, whose credit and performance must be assessed before dealing.

trading crude oil

Buying and selling cargoes and paper positions in crude.

trading hub

A location where physical trade concentrates and a reference price forms.

training data

The labelled examples a machine learning model is fitted to before it is applied to new data.

training delivery method

How training is delivered — classroom, online, on the job, blended.

training matchup

In order to create developments plans, SMEs align competency proficiency levels to identified training events that would close an employee competency gap in that area. Since the training matchup process links courses to specific levels of competency to close identified skill or knowledge gaps, it is important to consider the form of training selected, such as, e-Learning, instructor-led training, on-the-job training, etc. Other considerations include cost effectiveness, timeliness and whether the resource will deliver results that meet industry standards, statutory requirements and international acceptance (e.g., for accreditation or certification).

training needs analysis

Establishing what training is actually required before commissioning any.

training vs. development

Building capability for the current job against building it for future ones.

Trans-Alaska Pipeline System

The 800-mile insulated crude line from Prudhoe Bay to the ice-free port of Valdez, abbreviated TAPS.

transducer

A device that converts variations in a physical quantity (such as pressure, temperature, or brightness) into an electrical or mechanical signal, or vice versa. In gas measurement, any element or device that converts physical energy into mechanical or electrical energy.

transducers

A device that converts pressure to an electrical impulse for transmitting to a recording device, e.g., mini-computer.

transfer lact unit

The lease automatic custody transfer skid, metering and sampling oil off the lease without an operator present.

transfer learning

Adapting a model trained on one task to a related task, rather than training from scratch.

transfer of interest

Any assignment of a participating share, usually requiring consent and often triggering preemption.

transfer pump

A pump that pressures the oil from the storage tank through the LACT unit.

transfer tripping

A method of providing high-speed protection for transmission lines by tripping the breakers in one substation and then sending a trip signal to the substation at the other end of a faulted line.

transform fault

A strike-slip fault that offsets a spreading ridge, forming a plate boundary along which crust is neither created nor destroyed.

transformation lever

A structural change — bundling, standardization, demand reduction — that shifts cost rather than trimming it.

transformer

An electromagnetic device that transmits AC power from one circuit to another using electromagnetic induction, increasing or decreasing voltage to meet specific requirements.

transformer model

A deep learning architecture built on attention, which relates every element of a sequence to every other.

transgressing

Transgression occurs when the sea level rises and the shoreline moves backward across the land, causing flooding.

transgression

The landward migration of the shoreline as relative sea level rises faster than sediment can fill the space.

transgression, marine transgression

A marine transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, resulting in flooding. Transgressions can be caused either by the land sinking or the ocean basins filling with water. Transgressions may be caused by tectonic events such as orogenies, severe climate change or isostatic adjustments following removal of ice or sediment load.

transgressive

Pertaining to deposition during a transgression, with the shoreline stepping landward.

transgressive surface

The flooding surface at the base of the transgressive systems tract, separating it from the lowstand deposits below.

transient drainage radius

The distance the pressure disturbance has travelled into the formation at a given time during a test.

transient electromagnetic method

An electromagnetic survey in which a current is switched abruptly and the decaying secondary field is measured after the primary field has gone.

transient flow

Transient flow, is flow where the flow velocity and pressure are changing with time.

transient pressure

Pressure that is still changing with time because a rate change has not yet propagated to the reservoir boundaries.

transient pressure testing

Transient pressure testing records the pressure measurements as a function of time, in the wellbore at the productive interval, after the flow rate of the well is changed. They form the basis for well test analysis and are primarily used for determining the properties of the reservoir rock, skin effect and reservoir boundaries.

transient rate and pressure test analysis

Interpretation that uses the measured rate history alongside pressure, rather than assuming a constant rate.

transient-pressure response

The pressure change a well shows after its rate is altered, before boundaries are felt.

transistor

A semiconductor device that transfers an electrical signal across a resistor.

transit time

The amount of time that it takes sound waves to travel from a transmitter to the surface of a liquid, reflect off the surface and return to a receiver.

transition flow

The flow regime lying between two named regimes, where neither description holds cleanly.

transition fuel

A fuel, usually gas, argued to be acceptable while higher-carbon sources are displaced.

transition zone

In reservoir engineering, the section of reservoir between the fully saturated hydrocarbon levels and the fully saturated water levels, where saturations grade from 100% water at the base to irreducible water saturation higher in the reservoir above the free water level. In seismic acquisition, an area between land and marine environments, typically comprised of marsh, lagoon, or shallow water zones.

transitional state

The unsettled period between the old arrangement and the new, when performance usually dips.

translational slide

In translational slides, the mass displaces along a planar or undulating surface of rupture, sliding out over the original ground surface.

transmissibility

The product of permeability and thickness divided by viscosity, governing flow between grid cells.

transmission coefficient

The fraction of wave energy passing through an interface rather than reflecting.

transmission decay

The loss of amplitude as energy passes through successive interfaces.

transmission line

Two conductors arranged in such a way as to have constant physical parameters such as characteristic impedance. The cable used for PLC network connections is a transmission line.

transmission path

The means by which the fluid in a system is transported from one place to another.

transmission tomography

Tomography using the direct signal transmitted from a source in one well to receivers in another, rather than reflections.

transmitter

In process control, a device containing a sensing element that measures a process variable (pressure, temperature, flow, etc.), translates it into an output signal, and sends the signal to a controller or DCS. In sonic level measurement, the device that converts electrical energy into sound waves.

transmitter/receiver

A device used to send and receive transfer trip signals.

transparent tubing

A flexible, non-shrinkable tubing that is used basically as an insulating sleeve. Also called spaghetti tubing.

transport layer

The network protocol level that defines the data packets that transmitting and receiving devices pass back and forth, data flow control procedures, and error response routines.

transportation mode

Road, rail, sea or air, each with a different cost, speed and reliability profile.

transpression

Deformation combining strike-slip movement with a component of shortening across the fault.

transtension

Deformation combining strike-slip movement with a component of extension across the fault.

transverse dune

Transverse dunes are sand dunes formed across the direction of the winds that prevail in a given area.

transverse electric mode

An electromagnetic field configuration with a single electric field component and the two magnetic components perpendicular to it, abbreviated TE.

transverse isotropy

Anisotropy with a single symmetry axis, so properties are the same in every direction perpendicular to it but differ along it.

transverse isotropy vti

Vertical transverse isotropy, uniform horizontally but different vertically.

transverse magnetic mode

An electromagnetic field configuration with a single magnetic field component and the two electric components perpendicular to it, abbreviated TM.

transverse relaxation

The decay of the in-plane component of proton magnetization during a nuclear magnetic resonance measurement, characterized by T2.

transverse relaxation time

The transverse relaxation time (T2) is an indication of how fast the tipped protons in the fluids relax transversely, relative to the axis of the static magnetic field during nuclear magnetic resonance logging.

trap

A rock geometry with a seal that holds hydrocarbons in place instead of letting them migrate on.

trap discharge

The condensate a steam trap releases.

trap inlet

The inlet connection of a steam trap.

trap outlet

The discharge connection of a steam trap.

trap valve

The isolation valve serving a steam trap.

trap, hydrocarbon trap

A trap consists of a geometric arrangement of porous and permeable, reservoir and impermeable seal rocks which, when combined with the physical and chemical properties of subsurface fluids, can allow hydrocarbons to accumulate.

trapped oil

Oil immobilized in the pore space by capillary forces, which flooding alone cannot displace.

travel joint

A telescoping joint in a marine riser that takes up vessel heave while the riser stays connected to the seafloor.

travel time, sonic travel time, transit time

Travel time is the duration of the passage of a signal from the source through the Earth and back to the receiver.

traveling block

The moving sheave assembly that hangs in the derrick on the drilling line and carries the hook load.

traveling slips

The moving slip set at the top of a snubbing jack, which grips the pipe while the jack strokes it in or out.

traveling snubbers

The moving slips used on a snubbing unit under light-pipe conditions, when well pressure is pushing the string out.

traveling valve

The valve in a rod pump that is on the part of the pump that moves up and down with the pumping cycle.

traveltime

The time a signal takes to travel from source to receiver.

tray

A plate holding bubble caps and downcomers in a contactor column. There are usually 5 to 7 trays in each contactor column.

tray column

Column using discrete trays to stage contact between gas and liquid.

tray contactor

A trayed absorber where gas and solvent meet stage by stage.

tray dryer

A dryer that uses heat transfer and hollow shelves to dry material that is placed on trays.

tray packed column

A column combining trays and packed sections, taking the advantages of each over its own length.

tray packing

The contacting internals of a column, whether trays or packing.

treated emulsion

Emulsion that has been through heat or chemical treatment, whether or not it fully broke.

treater

A vessel that breaks an oil-water emulsion, usually with heat, so the oil meets pipeline water content specification.

treating

Removing sulfur, nitrogen and other contaminants so a stream meets product specification.

treating iron

The temporary high-pressure pipe, swivels and manifolds that carry treatment fluid from the pumps to the wellhead.

treating section

The section in a amine treatment unit in which amine contacts the sour fuel gas stream and H2S is absorbed by the amine.

treatment fluid

Any fluid pumped into a well to change the condition of the wellbore or the formation.

tree saver

A sleeve run through the production tree to carry treating pressure past its valves and bore.

trend

A consistent pattern, such as a gradual increase or decrease, in the value of a process variable over a period of time. On a control chart, a pattern of instability clearly showing a gradual upward or downward direction.

trend analysis

Reading patterns across many small events to find the weakness before a large one occurs.

triac

A three-terminal silicon device that functions as two SCRs configured in an inverse, parallel arrangement, providing a means of providing load current during both halves of the AC supply voltage. A TRIAC is generally used for motor speed control.

triangle

A closed shape that has three sides and three angles.

triangular distribution

A distribution defined by minimum, most likely and maximum, used where only those three are known.

triassic

The period whose strata host major reservoirs in the North Sea and elsewhere.

triaxial

Involving three mutually perpendicular axes, as in a rock strength test or a survey tool.

triaxial compression test

A triaxial compression test is when a cylindrical specimen of rock encased in an impervious membrane is subjected to a confining pressure and then loaded axially to failure.

tribolectric

Nuisance electrostatic charging, or Triboelectric charging, has become more and more common in the modern world, due primarily to widespread use of synthetic fabrics and plastics. These materials are good insulators and do not dissipate charge once it has been separated. Examples of such charging, such as those below, can be used effectively in electrostatic demonstrations.

triethylene glycol

The glycol most used to dehydrate natural gas.

trigger

In oscilloscopy, the circuit that initiates a horizontal sweep and determines the beginning point of the waveform. In digital electronics, a momentary change in input signals that causes the state of a flip-flop to change.

trigger hold-off control

A control that inhibits an oscilloscope's trigger circuit from looking for a trigger level for some specified time after the end of a waveform.

trigger level

The voltage level that a trigger source signal must reach before the trigger circuit initiates a sweep.

trigger pricing

A contract term letting the buyer fix the price on chosen days within an agreed window.

trim

Trim is an object's floating angle in the water, with respect to its fore and aft components.

trim components

Selected blend components whose amounts are increased or decreased during blending to maintain the target octane number and RVP.

trim cooler

Small exchanger making the final temperature adjustment after the main cooler.

trimming

Increasing or decreasing the amounts of selected components in a blend to maintain the target octane number and RVP.

trip

The immediate stop of an operating piece of equipment, such as a pump or turbine. In metering, the movement of a displacer from a starting point to a stopping point.

trip gas

The slug of gas that appears in the returns after a trip, from swabbing and from the time spent without circulation.

trip out

To pull the string out of the hole, joint by joint or stand by stand.

trip pill

A short slug of heavy mud pumped into the drillpipe before a trip so the string stands dry as it is pulled.

triple

Three joints (sections) of drill pipe (each approximately 30 ft / 9.1 m) screwed together.

triplex

A three-cylinder reciprocating pump, the standard configuration for mud pumps.

triplex pump

A reciprocating positive displacement pump with three plungers, the standard rig mud pump.

tripping drill pipe, tripping

The act of pulling the drill string or bottom hole assembly out of the hole, or replacing it in the hole. A round trip includes pulling out and returning to the bottom of the borehole.

tripping pipe

Running the drillstring into or out of the hole.

TRIR (Total Recordable Incident Rate)

Recordable injuries per two hundred thousand hours worked, the standard safety comparison measure.

trolley

A component that is mounted onto the bridge of an overhead crane and used to carry the hoist mechanism back and forth across the bridge.

troubleshoot

To locate and identify the cause of a problem.

troubleshooting

A process of detecting problems, determining their causes, and correcting the problems.

troubleshooting procedure

The ordered sequence for finding a fault, which prevents parts being changed at random.

trough

The maximum negative excursion of a seismic wavelet.

truck loading

Filling road tankers with product.

true amplitude recovery

Processing that restores relative amplitudes by removing spherical divergence, attenuation and other propagation losses.

true boiling point (TBP) curve

The laboratory distillation curve showing what fraction of a crude boils off at each temperature.

true dip

The maximum inclination of a plane from horizontal, measured perpendicular to its strike.

true formation resistivity

The resistivity of the undisturbed rock beyond the invaded zone.

true porosity

Porosity after correcting the log response for lithology and fluid effects.

true power

Power used to do useful work.

true resistivity

The resistivity of the formation beyond the invaded zone, symbol Rt.

true stratigraphic thickness

The thickness of a unit measured perpendicular to its bedding, corrected for both bed dip and well deviation.

true vertical depth

The vertical distance from a surface reference, usually the kelly bushing, down to a point in the well, abbreviated TVD.

true vertical thickness

The thickness of a bed measured vertically, as a vertical well would penetrate it.

truncation

Erosional cutting-off of a bed, which can form a trap where the eroded edge is sealed.

trunk line

The main pipeline of a gathering or export system, into which branch lines feed.

trunnion

The pair of pins that support a valve ball on a fixed axis so it turns without floating downstream.

trusted recovery

Restoring a system after failure in a way that does not reintroduce the compromise.

truth table

A tabular description of a logic function that lists all possible combinations of input variables together with the corresponding output variables for each state, used for Boolean functions such as AND, OR, NOT, IMPLIES, XOR, NAND, and NOR.

tube axial fan

A type of axial fan that is basically a propeller fan built inside a housing, which helps collect and direct the air.

tube boiler

A boiler whose heat transfer surface is formed of tubes.

tube exchanger

Shell-and-tube exchanger, the common form where pressures differ across the two sides.

tube heat exchanger

An exchanger transferring heat through tube walls.

tube leak

A failure of an exchanger or boiler tube, which mixes two fluids that must stay apart.

tube orifice fitting

The fitting holding an orifice plate in the line, allowing it to be changed without breaking pipe.

tube rupture

Failure of an exchanger tube, which mixes the two fluids at once.

tube side

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

tube wave

A low-frequency Stoneley wave travelling along the borehole fluid column.

tube-side fluid

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

tuberculocidal disinfectant

A hospital disinfectant used on inanimate surfaces and objects to destroy the bacteria that causes tuberculosis and other pathogenic microorganisms.

tubesheet

The plate an exchanger's tubes are fixed into, and the boundary between the two fluids.

tubing

Tubing, or production tubing, is a wellbore tubular used to produce reservoir fluids. Production tubing is assembled with other completion components to make up the production string.

tubing annulus

The space between tubing and casing.

tubing broach

A cutting tool jarred through damaged tubing to restore its bore by removing metal.

tubing diameter

The tubing bore, which trades friction loss against the ability to lift liquid.

tubing displacement

A batch treatment in which inhibitor is pumped down the tubing and displaced to the bottom, coating the string as it passes.

tubing grade

The steel specification of a tubing joint, setting its yield strength and its suitability for sour service.

tubing hanger

The wellhead component that suspends the tubing string and seals the annulus around it.

tubing head

The wellhead spool that receives the tubing hanger and provides the connection to the Christmas tree.

tubing head pressure

Pressure at the top of the tubing, the simplest continuous indication of well performance.

tubing job

A workover in which the production tubing is pulled and rerun or replaced.

tubing joint

A single length of tubing, typically about 30 ft, made up with others into the production string.

tubing performance curve (TPC)

A plot of flowing bottomhole pressure against production rate for a given tubing string, abbreviated TPC.

tubing pressure

The pressure at the wellhead on the tubing side, as read on the tree gauge.

tubing pump

A rotary positive displacement pump that moves liquid by squeezing it through flexible tubing.

tubing puncher

A shaped charge gun of limited penetration, used to hole an inner string without damaging the string outside it.

tubing retrievable

Designed to come out with the tubing rather than separately on wireline.

tubing seal assembly

The seal stack on the bottom of the tubing that engages the polished bore of the packer.

tubing size

The tubing's diameter, chosen to balance friction loss against liquid loading.

tubing string

The pipe run inside casing through which production flows to surface.

tubing testing tool

A plug set in the tubing so the string above it can be pressure tested as it is run or after it is landed.

tubing thread

The connection used to join tubing joints, from API round thread to premium metal-to-metal designs.

tubing wall

The tubing's wall, whose thickness sets burst and collapse ratings.

tubing-casing annulus

The annular space between the production tubing and the casing.

tubing-conveyed perforating (TCP)

Perforating with guns run on tubing, drillpipe or coiled tubing rather than on wireline, abbreviated TCP.

tubing-end locator (TEL)

A tool with sprung arms that catch on the tubing shoe, giving a positive depth reference downhole, abbreviated TEL.

tubing-retrievable safety valve (TRSV)

A subsurface safety valve made up as part of the tubing string, abbreviated TRSV.

tubingless completion

A slimhole completion producing through small-diameter casing with no separate tubing string.

tubular jar

A slickline jar built as a tubular body, delivering an upward impact blow to free a stuck tool string.

tubular reactor

A reactor in which reaction occurs as fluid passes through tubes.

tubulars

Collective term for oilfield pipe of any kind — drillpipe, collars, casing, tubing and line pipe.

tubulence

The flow of a fluid in an erratic, nonlinear motion caused by pipe fittings, valves, rough surfaces, etc.

tuckman's model of team development

The observation that teams pass through predictable stages before performing.

tuff

Rock formed from consolidated volcanic ash.

tuffs

Rocks formed from consolidated volcanic ash, sometimes reservoirs and often seals.

tuition reimbursement

Employer funding of employee study, usually tied to continued service.

tune

To set the parameters of a control algorithm.

tuned circuit

A circuit that uses components to determine the frequency of the signal produced by an oscillator.

tuning effect

The interference between reflections from the top and base of a thin bed, which reinforce or cancel depending on the bed's thickness.

tunnel diode

A specially designed diode that can be highly conductive in both directions because it is heavily doped and has a very thin P-N junction. It has a unique characteristic of having a negative resistance in the forward-biased direction. The negative resistance region makes it highly effective as a high-speed switch.

turbidite

Turbidites are sand deposits that flow from shallow regions into deeper water following meandering channels, which are progressively stacked as deposition continues.

turbidite sandstone

Sand deposited by density currents in deep water, a major deepwater reservoir type.

turbidite system

The connected channels and lobes deposited by turbidity currents in deep water.

turbidite, turbidity flows

A turbidite is the geologic deposit of a turbidity current, which is a type of sediment gravity flow responsible for distributing vast amounts of clastic sediment.

turbidites

Turbidites are sedimentary rocks formed by a turbidity current, a subaqueous sediment gravity flow that transports sediment into deep-marine environments. They are characterized by distinct layering and grading as larger particles settle out first, followed by finer ones.

turbidity

A measure of the cloudiness or concentration of suspended particles in a liquid or solution.

turbidity current

A dense, sediment-laden flow that runs downslope beneath clearer water under its own excess weight.

turbidity currents

A turbidity current is a dense, sediment-laden flow of water that moves downslope in a body of water. The added sediment makes the water denser and heavier than the surrounding clear water. These currents transport vast amounts of sediment from shallow areas to deeper regions and can erode the seafloor.

turbidity meter

An instrument that measures the concentration of suspended particles in a solution.

turbine

A machine for generating rotary mechanical power from the energy of a stream of fluid (such as water, steam, or hot gas), converting kinetic energy to mechanical energy through the principles of impulse and reaction, or a mixture of the two. In power plants, it converts energy stored in steam, water, or combustion gases into the mechanical energy needed to turn a generator.

turbine control

The governing system holding turbine speed and load.

turbine control valve

The valve modulating steam to the turbine to hold speed or load.

turbine control valves

Specially designed, hydraulic cylinder operated valves that determine the amount of steam entering the turbine.

turbine flowmeter

A meter inferring flow from the speed of a rotor turned by the stream.

turbine shaft

The rotating shaft carrying a turbine's blades.

turbine trip

A sudden shutdown of a turbine by quickly closing all steam supply valves, shutting off all steam flow. May also trip the generator and boiler, and may occur in response to an emergency situation.

turbulence

The flow of a fluid in an erratic, nonlinear motion caused by pipe fittings, valves, rough surfaces, etc.

turbulent flow

Flow in which fluid particles move chaotically across the flow direction as well as along it.

turn-off time (shutdown)

The time from when the turn-off voltage is applied to the shutdown pin to when the supply current has reached half of its final value.

turn-off voltage (shutdown)

The voltage required on the shutdown pin to turn the device off.

turn-on time (shutdown)

The time from when the turn-on voltage is applied to the shutdown pin to when the supply current has reached half of its final value.

turnbuckle

A rigging component or device used to make small adjustments in the length or tension of a wire rope, chain, or sling leg.

turning gear

A motor and gear arrangement that keeps the turbine rotor turning at a constant speed to maintain uniform cooling of the rotor and thus prevent it from warping, bowing, or sagging during turbine shutdown or prior to startup.

turnkey

A drilling contract in which the contractor is paid a fixed sum for delivering the well, carrying the cost risk of how long it takes.

turnover

The rate at which employees leave and are replaced.

turns ratio

The ratio of the number of turns of wire in the primary winding of a transformer to the number of turns in the secondary winding.

twist off

To part the drillstring downhole through fatigue or excessive torque.

twisted pair

A type of cable in which pairs of conductors are twisted together to minimize interference pickup.

two-cycle engine

Engines that perform intake, compression, power and exhaust in two strokes of the piston, providing one revolution of the crankshaft.

two-dimensional seismic data

Seismic data acquired and displayed as a single vertical section along a line.

two-dimensional survey

Seismic acquired as individual lines with wide, unsampled gaps between them.

two-holing

A method of installing flanges so that the bolt holes of each flange half line up.

two-pass condenser

A type of condenser that has a partition to divide one waterbox into inlet and outlet sections so that circulating water can make two passes through the condenser.

two-pass method

A production logging technique using an up pass and a down pass over the same interval so that tool and fluid velocities can be separated.

two-phase

Separation into gas and liquid.

two-phase separation

Separating natural gas from liquids.

two-phase flow

The simultaneous flow of two phases, most often gas and liquid, in the same conduit.

two-phase sample

A sample which contains both gas and liquid; creates inaccurate sample analysis.

two-phase separation

Separating natural gas from liquids.

two-phase separator

A vessel that splits the wellstream into a gas stream and a combined liquid stream.

two-phase vertical separator

Vertical vessel splitting gas from liquid, with no water draw.

two-slot addressing

An I/O addressing scheme where a pair of slots in the I/O rack is defined as a 16-bit group.

two-stage tender process

Inviting technical proposals first and opening commercial offers only from those that qualify.

two-way traveltime

The time for seismic energy to travel from the surface to a reflector and back, the vertical axis of a time section.

TWT

Two-way traveltime — the time for seismic energy to reach a reflector and return to the surface.

type curve analysis

Type curve analysis is a method for quantifying well and reservoir parameters such as permeability, skin damage, fracture half-length, dual porosity parameters, by comparing the pressure change and its derivative of the acquired data to reservoir model curve families, called type curves.

type curves

Families of dimensionless pressure and derivative curves computed from reservoir models, matched against test data to identify the model.