Discover the IHRDC Energy Glossary_beta

C chart

An attribute control chart used to plot the number of defects per item, or sample.

C pump

A centrifugal pump, as used at the rig for mixing and transferring drilling fluid.

cable

In wireline logging, a cable used to lower tools into the well and transmit signals, consisting of a central section with conductors surrounded by metal, load-bearing armor. In electrical work, two or more insulated conductors bound together in a common covering; a large conductor.

cable clips

Devices used to attach a length of wire or cable to a housing or frame.

cable head

The electromechanical connector at the top of a tool string that joins it to the logging cable, carrying both the load and the conductors.

cable ties

Plastic straps that can be used to tie together bundles of individual wires to keep them neatly organized.

cable, wireline cable

The cable is used to lower wireline logging tools into the well and through which signals from the measurements are passed. The cable consists of a central section with conductors surrounded by a metal, load-bearing armor.

cable-tool drilling

Percussion drilling in which a heavy bit on a cable is repeatedly dropped to pound the rock, with cuttings bailed out periodically.

CAD

An acronym for "computer-aided design? CAD equipment is commonly used to create original drawings, which can then be reproduced as needed.

cake

The solids left behind on a permeable surface after a slurry has been filtered against it under pressure. The liquid that gets through is the filtrate.

cake thickness

The thickness of filter cake, measured in a fluid loss test and reported in thirty-seconds of an inch.

calcareous

Calcareous refers to something (in this case a shell) that is formed from or contains a high proportion of calcium carbonate, in the form of calcite or aragonite.

calcined coke

Petroleum coke heated to drive off volatiles, used to make anodes for aluminum smelting.

calcite

The rhombohedral crystalline form of calcium carbonate and the chief constituent of limestone and chalk — the stable polymorph at surface conditions.

calcium bromide

A dense soluble salt used to make heavy completion and workover brines, often blended with calcium chloride.

calcium carbide

Calcium carbide, also known as calcium acetylide, is a chemical compound with the chemical formula of CaC2.

calcium carbonate

The compound CaCO3, occurring as calcite and as aragonite, and the material of limestone.

calcium carbonate plug

A temporary plug of graded calcium carbonate circulated into place and left to settle.

calcium chloride

The salt CaCl2, used to accelerate cement, to make dense clear brines, and as a desiccant for dehydrating gas.

calcium contamination

The unwanted entry of calcium ions into a water-base mud, from cement, gypsum or formation water, which flocculates the clay and raises fluid loss.

calcium hydroxide

Ca(OH)2, slaked or hydrated lime, used in lime muds and to raise pH.

calcium mud

A water-base mud deliberately treated with soluble calcium to inhibit shale swelling.

calcium naphthenate

A hard soap formed when naphthenic acids in the crude react with calcium in the produced water.

calcium oxide

CaO, quicklime, which slakes to calcium hydroxide on contact with water.

calcium sulfate

CaSO4, occurring naturally as anhydrite and, hydrated, as gypsum.

calcium test

The titration that determines calcium concentration in a mud filtrate, using a hardness indicator and EDTA.

calibrate

To adjust an analyzer before use; helps ensure accurate measurements.

calibration

The process of comparing and, if necessary, restoring the accuracy of a measurement tool or controller to a standard.

calibration procedure

The written method for checking and adjusting an instrument against a standard.

calibration, tool calibration

Calibration is a method of adjusting a data set against a control that has properties to which the data set should conform. Tool calibration is the process of establishing the relationship between a measuring device and the units of measurement. This is done by comparing a device, or the output of an instrument, to a standard having known measurement characteristics.

caliche

Caliche (also known as calcrete, hardpan, or duricrust) refers to a sedimentary rock formed in arid and semi-arid regions when calcium carbonate precipitates out of solution cementing soil, sand, gravel, or other loose sediments together.

caliper

A measurement tool that has adjustable legs or jaws.

caliper log

A log of borehole diameter against depth, measured by one or more arms riding the wall.

caliper, caliper log

A caliper log is a representation of the measured diameter of a borehole along its depth.

call and put

The right to buy and the right to sell respectively.

cam ring

The profiled ring converting rotation into radial movement of vanes or pistons.

camco

A long-established maker of gas lift and downhole flow control equipment.

camera

The film recorder used in early logging to write measurements onto photographic film.

camshaft

The shaft whose profiled lobes time valve movement.

candidate

A member of the workforce (employee) whose performance in the workplace is to be assessed.

candidate evaluation

Assessing applicants against defined criteria rather than against each other.

cap

A small, electrically fired charge used to initiate a larger explosive — a blasting cap.

cap rock

An impermeable shale, anhydrite, or salt that forms a seal above the reservoir so that fluids cannot migrate upwards.

cap the well

To regain control of a blowing well by fitting and closing a valve or stack on the wellhead.

capacitance

A physical property of all circuits that opposes changes in voltage; the ability to store electrical energy in the form of an electrostatic field. Measured in farads and typically represented by a capital C in electrical formulas.

capacitance filter

A filter circuit that smooths out a pulsating DC voltage. The circuit stores energy as the rectifier's output pulse increases and releases the stored energy as the rectifier's output pulse begins to decrease.

capacitance log

A production log reading the dielectric capacitance of fluid passing a sensor, to tell water from hydrocarbon.

capacitance meter

A production logging sensor that infers water holdup from the very different dielectric constants of water and hydrocarbon.

capacitance probes

Metal rods that extend into a tank to provide level measurements based on changes in the electrical capacitance between two surfaces separated by a dielectric (non-conducting) liquid.

capacitive

Working by change in electrical capacitance, as in a level probe.

capacitive power

Non-working power that is a result of charging current, such as the charging current required to energize long high-voltage lines.

capacitive reactance

The opposition to AC current flow provided by a capacitance, measured in ohms. Typically represented as XC in electrical formulas.

capacitor

A passive component that stores energy in the form of an electrostatic field, used to control and/or increase the amount of capacitance in an electrical circuit.

capacitor bank

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

capacitor-input (pi) filter

A filter circuit that combines the operation characteristics of a capacitance filter and an inductance filter.

capacity

The maximum load weight that equipment can support or lift, or the amount of electric power for which a generator, turbine, transformer, transmission circuit, station, or system is rated by the manufacturer.

capacity and constraints

What the system can produce, and the specific bottleneck that limits it.

capacity charts

Charts provided by a crane manufacturer that list and explain vital information about a crane's operating capabilities and lifting capacities.

capacity factor (of a valve), Cv, Kv

The flow a valve passes at a defined pressure drop — US gallons of water per minute at 1 psi for Cv, m3/h at 1 bar for Kv.

CAPEX

Capital expenditures.

CAPEX estimation methods

The techniques for costing a project, from analog scaling early to detailed take-off at sanction.

capillary action, capillarity, capillary

Capillary action, or capillarity, is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to, external forces like gravity.

capillary bound water

Capillary bound water is immobile water held by capillary forces in regions of microporosity.

capillary force

Capillary force is the differential force between adhesion and gravity.

capillary number

The dimensionless ratio of viscous forces to interfacial tension forces acting on a trapped oil droplet.

capillary pressure

The pressure differential between two immiscible fluid phases occupying the same pores, caused by interfacial tension between the two phases. It results from interactions of forces acting within and between fluids and their bounding solids, and must be overcome to initiate flow.

capillary pressure curve

The relationship between capillary pressure and the saturation of non-wetting phase it will drive into a rock.

capillary suction time test

A quick filtration test timing how long free water from a mud sample takes to travel between two electrodes on filter paper, abbreviated CST.

capillary tube

A tube narrow enough for surface tension to dominate, and the model for a pore throat.

capillary tube viscometer

An instrument measuring viscosity from the pressure needed to drive fluid through a fine tube at a known rate.

capital allocation

Deciding which projects get funded from a constrained budget.

capital campaign

A time-limited appeal for a large one-off purpose such as a building.

capital discipline

Refusing to invest simply because funds are available or prices are high.

capital intensive

Requiring large upfront investment relative to operating cost, as most energy projects are.

capital project governance

The structure of authorities, gates and assurance that keeps large spending under control.

capitalism

An economic system based on private ownership and market allocation.

capricorn (trading profit exercise)

The oil trading exercise in which teams calculate the profit on a completed deal.

caprock effect

The positive gravity anomaly produced by a dense anhydrite and limestone cap over an otherwise low-density salt dome.

capstone activity

The final exercise requiring participants to integrate everything the program covered.

capsule gun

A perforating gun whose shaped charges are individually sealed in pressure-tight capsules mounted on an exposed carrier.

Captain of the Port order

A United States Coast Guard directive restricting or halting operations at a waterfront facility.

capture cross-section

The effective cross-sectional area that an atom of an isotope presents to absorption of neutrons, and is a measure of the probability of neutron capture. The unit of measure is cm²/cm³ = 10³ c.u., where c.u. is the capture unit.

capture cross-sections

Capture cross-sections are a measure of the probability that a neutron, or gamma ray, will be captured by an atom.

capture gamma ray

A capture gamma ray is generated by the capturing of a thermal neutron by a chlorine atom.

car seal program

The control that keeps critical valves locked in position and records any change.

carbide

A hard material used for bit cutters and wear surfaces.

carbide lag test

Dropping a carbide capsule into the drillpipe and timing the acetylene it generates back to surface, to measure circulating lag.

carbon adsorption

Removing contaminant by adsorbing it onto activated carbon.

carbon adsorption system

A system that uses particles of activated carbon to remove organic compounds and eliminate foul odors from a gas stream.

carbon budget

The cumulative emissions still permissible for a given temperature outcome.

carbon canister

A vessel of activated carbon adsorbing vapors from a vent before it reaches atmosphere.

carbon capture and storage (CCS)

Process by which carbon dioxide emissions are captured and removed from the atmosphere and then stored, normally via injection into a secure underground geological formation.

Carbon Capture, Utilization and Storage (CCUS)

Capturing carbon dioxide and either using it or injecting it into permanent geological storage.

carbon density

The concentration of carbon atoms in the oil, which the carbon-oxygen log's response depends on.

carbon dioxide

A chemical compound (CO2) made up of molecules each having one carbon atom covalently double-bonded to two oxygen atoms. At room temperature it is a colorless gas, heavier than oxygen, that does not support combustion.

carbon dioxide corrosion

Metal loss driven by carbonic acid where carbon dioxide dissolves in produced water — sweet corrosion.

carbon dioxide equivalents (CO2e)

The quantity that describes, for a given mixture and amount of greenhouse gas, the amount of CO2 that would have the same global warming potential (GWP) when measured over a specified timescale (generally 100 years).

carbon dioxide system

A type of fire protection system that uses carbon dioxide to blanket a fire and to extinguish it by removing its source of oxygen.

carbon emission

Carbon dioxide released to atmosphere, the quantity every decarbonization target is written against.

carbon footprint

The total greenhouse gas emissions attributable to an organization, product or activity.

carbon intensity

The quantity of greenhouse gas emissions associated with producing an intermediate or final product. For the oil and gas industry, carbon intensity is commonly expressed in units of Tonnes CO2e per product volume (e.g. Tonnes CO2e/bbl or Tonnes CO2e/MCF).

carbon isotope

The ratio of carbon isotopes, used to identify the origin of gas and to correlate strata.

carbon monoxide

A colorless, odorless, poisonous gas produced by the incomplete combustion of materials that contain carbon, such as fuels in internal combustion engines. Mild poisoning causes symptoms such as nausea, dizziness and headaches, while severe poisoning can result in brain or heart damage and death.

carbon seal

A seal consisting of carbon rings that are held against the turbine shaft by springs.

carbon sequestration

The fixation of atmospheric carbon dioxide in a carbon sink through biological or physical processes.

carbon sink

A reservoir that absorbs or takes up released carbon from another part of the carbon cycle. The four sinks, which are regions of the Earth within which carbon behaves in a systematic manner, are the atmosphere, terrestrial biosphere (usually including freshwater systems), oceans and sediments (including fossil fuels).

carbon/oxygen log

A carbon-oxygen (C/O) log measures the carbon content of a formation and its contained fluids. The ratio of the carbon to the oxygen measurement, or C/O, enables the evaluation of differences in the water and oil saturations independent of the formation water salinity.

carbonaceous

Rich in carbon, as coaly or organic-rich rock.

carbonate

A sedimentary rock whose main mineral constituents are calcite and dolomite. Carbonate deposition occurs in shallow-water platforms, shelves, ramps, warm shallow seas, atolls, and deepwater basins, and is a product of precipitation rather than sediment transportation.

carbonate buildup

A mound of carbonate constructed in place, standing above the surrounding sea floor.

carbonate gamma ray

A gamma ray curve with the uranium contribution removed, leaving only potassium and thorium.

carbonate ion

The anion CO3 2-, one member of the pH-dependent equilibrium linking dissolved carbon dioxide, bicarbonate and carbonate in water.

carbonate platform

A broad shallow area where carbonate accumulates in place.

carbonate reservoir

Reservoir in carbonate rock, where permeability is often controlled by fractures and dissolution rather than by grains.

carbonate rock

Rock of calcium or magnesium carbonate, whose porosity is created and destroyed after deposition.

carbonate sand

Sand-sized carbonate grains, deposited where they formed rather than transported far.

carbonate scale

Mineral deposit, mostly calcium carbonate, laid down on tubulars and equipment as produced water falls out of saturation with changing pressure and temperature.

carbonate sediment

Sediment of carbonate grains, usually produced biologically in place rather than transported.

carbonate sediments

Carbonate sediments are formed in shallow, warm oceans either by direct precipitation out of seawater or by the biological extraction of calcium carbonate from seawater to form skeletal material. The sediment is, therefore, composed of varying sizes and shapes of particles that are mixed together, creating a variety of textures. This sediment may be bound together by encrusting organisms or deposited loosely and subject to transport by ocean currents.

carbonate shelf

A shallow platform where carbonate is produced and deposited in place.

carbonate test

The Garrett gas train procedure that measures carbonate and bicarbonate in mud filtrate by acidifying it and measuring the CO2 released.

carbonates

Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals.

carboxymethyl

The chemical group in cellulose derivatives used to control filtration.

carboxymethyl hydroxyethylcellulose

A cellulose polymer carrying both anionic carboxymethyl and nonionic hydroxyethyl groups, used to viscosify water-based treatment fluids.

carboxymethyl starch

An anionic starch derivative used for filtration control, abbreviated CMS.

carboxymethylcellulose

An anionic cellulose polymer used in drilling fluids for filtration control.

carburizing flame

An oxy-fuel gas welding torch flame that bums excess acetylene. Characterized by a white streak, or "feather", "inside a bright blue "outer flame envelope."

carcinogen

Any substance that has been found to cause cancer.

career development life cycle

The stages of a working life, and what an employer can usefully offer at each.

career objectives

What one is trying to achieve professionally, stated concretely enough to act on.

career path

A feature in CMS Online that allows employees to compare their assessment results for their current job title against the requirements for all other job titles in the career path.

caregiving benefit

Support for employees with dependants, such as childcare or eldercare provision.

cargo crude

A shipment of crude oil sold and moved as one parcel.

cargo handling

The loading, discharge and measurement operations at each end of a voyage.

cargo insurance

Cover against loss or damage to goods in transit.

cargo tonne

The metric tonne of cargo on which freight and canal charges are calculated.

carpal tunnel syndrome

An MSD that results when tendinitis or any other swelling in the wrist puts pressure on the median nerve as it passes through the carpal tunnel. The carpal tunnel is a small opening in the wrist through which the median nerve and nine tendons that connect the muscles in your arm to the bones of your hand pass. Early symptoms of carpal tunnel syndrome include a tingling or a numb sensation in any of the first three fingers or the thumb.

carried interest

An interest whose costs another party funds up front, recovered later out of production.

carried working interest

This represents a situation where one working interest owner covers all or part of the capital costs for exploration, and potentially development, on behalf of another company. The carrying party is repaid out of the carried party's subsequent production cash flow. Note that the “carried” owner does not take the risk of exploration because it does not make an investment during exploration. Repayment is made only out of the profits made from production. On the other hand, the carrying party usually receives an uplift on its investment (i.e. 1.5 - 4.0 times its investment) from the carried party's cash flow.

carrier air

A supply of air used to provide aeration to catalyst in the spent catalyst standpipe.

carrier fluid

The fluid whose job is to transport solids — proppant, gravel or lost circulation material — into or out of the wellbore.

carrier gas

A gas used to carry or transport a sample through a gas chromatograph and its column.

carrier gun

A perforating gun whose charges sit inside a sealed steel carrier that contains both the debris and the pressure.

carrier solvent

In liquid extraction, the liquid in which the solute is dissolved.

carry arrangement

Any structure where one party funds another's share, recovering it later out of revenue.

carrying capacity

The ability of circulating drilling fluid to lift rock cuttings out of the wellbore.

carryover

A condition where gas carries liquid (glycol or amine solution) out of a vessel.

cartridge

In wireline logging, the section of a tool that contains the telemetry, electronics, and power supplies, as distinct from the sonde that contains the measurement sensors. In safety, a filter containing a chemical absorbing material used to remove airborne particles and low concentrations of hazardous gas from the air.

cartridge filter

A filter using a replaceable cylindrical element.

cartridge fuse

A fuse enclosed in an insulating cylindrical casing to confine the arc when the fuse opens, composed of a fuse link, a casing, and two contact points.

cartridge respirator

A type of air purifying respirator that uses a cartridge to remove airborne particles and low concentrations of a hazardous gas.

CAS identification number

A number assigned by the Chemical Abstracts Service to designate a single substance or a substance with a complex structure that has a unique chemical name.

CAS number

A unique number assigned to a chemical by the Chemical Abstracts Service.

cascade control

A type of process control consisting of a master (primary) control loop and a slave (secondary) control loop, where the output of the primary loop becomes the set point of the secondary loop.

cascaded loops

A system of master (primary) and slave (secondary) control loops. The primary loop output is the set point of the secondary loop.

cascading drain system

Arrangement of drain lines so that drips flow from heater to heater in a train, or string, of heaters.

cascading vent system

Arrangement of vent lines so that air and non-condensible gases flow from heater to heater in a train, or string, of heaters, then on to a common vent line that is usually connected to the de-aerator or the main condenser.

case study method

Learning by analyzing a real situation and defending a recommendation.

case study simulation

A worked scenario participants run through to practice the method.

case temperature for 60 seconds

Usually specified as an absolute maximum. It is meant to be used as guide for automated soldering processes.

cased borehole

A cased hole is a wellbore that has been lined with cemented steel.

cased hole

The portion of the wellbore that has had metal casing placed and cemented to protect the open hole from fluids, pressures, and wellbore stability problems.

cased hole log

A measurement recorded through casing after the well is completed.

cash budget

The forecast of cash receipts and payments, which can differ sharply from profit.

cash call

The operator's demand that each partner fund its share of the approved budget.

cash flow statement

The statement reconciling profit to the cash actually generated and spent.

casing

Large-diameter, thick-walled steel pipe lowered into an open borehole and cemented in place to isolate formation fluids (such as fresh water), prevent borehole collapse, and withstand forces such as collapse, burst, and tensile failure.

casing bolt

A bolt clamping a machine casing.

casing bowl

The profile in the wellhead where a casing hanger lands and seals once the string has been run.

casing burst pressure

The internal pressure differential at which a casing joint will rupture.

casing centralizer

A device fitted outside the casing to hold it off the wellbore wall so cement can circulate all the way round it.

casing collar

The threaded coupling that joins two joints of casing.

casing collar locator (CCL)

A tool detecting casing collars magnetically, giving fixed references to correlate depth against before perforating or treating.

casing collar log

The record a casing collar locator produces, usually alongside a gamma ray curve, showing collar positions against depth.

casing completion

A completion in which production casing is set across the reservoir and perforated, rather than the interval being left open.

casing coupling

The threaded sleeve that joins two casing joints.

casing flange

The flanged joint in a machine casing.

casing grade

The classification of casing steel by yield strength — H-40, J-55, N-80, P-110 and the rest.

casing gun

A large-diameter perforating gun run before the tubing is installed, when the full casing drift is still available.

casing halves

The two halves of a split casing.

casing hanger

The wellhead component that transfers a casing string's weight to the casing head or spool, centers the string and seals against it.

casing hardware

The equipment run attached to a casing string — guide shoes and float equipment, wiper tools, centralizers and scratchers.

casing head

The wellhead component landing the first casing string, connecting it to the BOP stack while drilling and to the spools afterwards.

casing inspection log

A log of casing wall thickness and integrity, run to find corrosion, wear and holes.

casing joint

A single length of casing, typically around 40 ft, threaded at both ends.

casing patch

A sleeve or liner set across damaged casing to restore its pressure integrity.

casing point

The depth chosen to stop one hole size, so that its casing string can be set and cemented before drilling continues.

casing potential profile

A log of the small galvanic voltages on the inner wall of a casing, used to assess cathodic protection.

casing pressure

The pressure measured at surface on the casing annulus.

casing reciprocation

Moving the casing string up and down during cementing, to break the mud's gel and improve displacement.

casing scraper

A tool with spring-loaded blades run to strip cement, scale and debris from the inside of casing.

casing shoe

The casing shoe is the bottom of the casing string, including the cement around it.

casing shoe test

A pressure test on the formation just below a newly cemented casing shoe, confirming it will hold the mud weight the next section needs.

casing size

The casing diameter, which fixes what can be run inside it for the rest of the well's life.

casing spool

A flanged wellhead component that lands and seals the top of a casing string and carries the connection for the next one up.

casing string

A full length of connected casing joints run into a hole section and cemented in place.

casing swage

A crossover joint connecting two sizes of casing within one string.

casing test

A drillstem test run inside casing rather than in open hole — also called hook wall testing.

casing thread

The threadform on casing joints, which must carry structural load and seal against the pressures and fluids the string will see.

casing tubing

The casing and tubing strings that make up the well's mechanical envelope.

casing valve

A valve on a wellhead side outlet giving access to a casing annulus.

casing wearing ring

A replaceable ring in the pump casing taking the wear that would otherwise damage the casing.

cat cracked gasoline

A high-quality gasoline feed from a cat cracker that is sent to the gasoline blending area.

cat cracker

A reactor process system that uses relatively low pressures, high temperatures, and a fluidized catalyst to break (crack) long-chain hydrocarbons in gas oils and other fractions into more valuable shorter-chain hydrocarbon products.

cat cracking

A petroleum refinery process in which heavy oil is passed through metal chambers called catalytic crackers or cat-crackers, under pressure and high temperature in the presence of catalysts. This boiling breaks up heavy, large, and more complex long-chain oil molecules into lighter, smaller, and simpler short-chain molecules, such as those of gasoline.

cat line

A light rope or cable driven from a cathead, used to lift and position small equipment on the rig floor.

CAT scan

A CAT scan, produces an image of the internal structure of a cross-sectional slice through an object by reconstructing a matrix of x-ray attenuation coefficients.

CAT scanning

CAT scanning is a non-destructive x-ray technology.

cataclasite

A rock crushed and granulated by movement on a fault, without the mineral alignment that a mylonite shows.

cataclastic

Describing rock deformed by fracture and grinding of its grains under high stress, rather than by crystal-plastic flow.

catagenesis

The intermediate-temperature alteration of organic matter, beginning where thermal hydrocarbon generation starts and ending as bitumen generation ceases.

catalyst

A substance that increases or decreases the rate of a chemical reaction without being significantly affected by or becoming part of the final product.

catalyst activity

How effectively catalyst promotes the reaction, which falls with coking and poisoning.

catalyst burn

After unit preparation, the next major step in catalyst regeneration, in which air is used to burn carbon deposits off of the catalyst.

catalyst circulation

The flow of catalyst between the reactor and the regenerator of a fluid catalytic cracking unit.

catalyst flow

The circulation of catalyst between reactor and regenerator.

catalyst regeneration

The process of burning, or oxidizing, the carbon deposits off of a catalyst.

catalyst-to-oil ratio

A comparison of the amount of catalyst to the amount of charge entering the cat cracker riser.

catalysts

Materials that speed up or slow down chemical reactions.

catalytic cracker

A reactor system used to break down relatively large hydrocarbons into smaller hydrocarbons.

catalytic cracking

Breaking heavy gas oil into gasoline-range molecules over a catalyst.

catalytic cracking unit

The unit cracking heavy gasoil over catalyst into lighter products.

catalytic reaction section

The section of a sulfur recovery unit in which sulfur is removed from a mixture that contains H₂S and SO₂.

catalytic reactor

A reactor in a sulfur recovery unit in which H₂S and SO₂ are reacted over a catalyst.

catalytic reformer

A unit that uses a catalyst to reform the naphtha fraction into more valuable products.

catalytic reforming

Reforming processes that are accelerated or enhanced by exposing the process stock to catalysts under controlled conditions.

catalytic reforming unit

The refinery unit rearranging naphtha molecules over catalyst to raise octane and make hydrogen.

catastrophic failure

This type of ESD damage causes some sort of permanent damage, such as an oxide failure or a metal melt.

catch basin

A tray or other type of vessel for capturing water or spills of other liquids.

categories of financial ratios

Liquidity, solvency, profitability, efficiency and market ratios.

cathead

A clutched spool driven from the drawworks, used to pull chain, cable or rope when making up and breaking out connections.

cathode

The part of a corrosion cell at which chemical reactions take place that use the electrons that were released at the anode.

cathodic

Relating to cathodic protection, which prevents corrosion by making the steel the cathode.

cathodic protection

A means of protecting an above ground storage tank from corrosion.

cation

A positively charged ion—an atom or molecule in which the total number of electrons is less than the total number of protons, giving it a net positive electrical charge.

cation exchange

Clay's ability to swap ions with pore water, which adds conductivity and distorts resistivity logs.

cation exchange capacity

A measure of the ability of clays (such as montmorillonite, chlorite, illite, and kaolinite) to exchange cations between the clay surfaces and surrounding water. It is the number of exchangeable cations per dry weight that a rock is capable of holding at a given pH value. Commonly termed the shale factor in mud logging.

cation exchange capacity (CEC)

Cation exchange capacity is the quantity of positively-charged ions (cations) that a clay mineral can accommodate on its negatively-charged surface.

cationic

Carrying a positive charge.

cations

Positively charged ions.

catwalk

The raised steel platform beside the rig at the foot of the pipe ramp, used to lay out and prepare tubulars.

caustic

Corrosive, capable of destroying or eating away by chemical reaction. Opposite of acidic. A solid or liquid having these properties.

caustic extraction test

A test boiling a barite sample in caustic soda to reveal soluble sulfide or carbonate contamination.

caustic potash

Potassium hydroxide, used to raise pH and as the source of potassium ions in potassium-polymer muds.

caustic soda

See Sodium hydroxide.

caustic treater

A piece of equipment that uses a solvent caustic material to absorb mercaptans from an alkylation feed stream.

caustic wash

Acid removal equipment used to neutralize sulfuric acid carried over in the reactor effluent.

caustic washing

The process of using caustic on a product before or after a treatment or refining step.

cave effect

The distortion of an induction log where a washout or cave abruptly enlarges the borehole.

cavern storage

Gas or liquid stored in a solution-mined salt cavern, valued for fast injection and withdrawal.

cavern storage facility

A gas or liquid storage facility using solution-mined salt caverns.

caving

Formation falling into the hole, which contaminates cuttings samples and can stick pipe.

cavings

Rock fragments that reach surface from the wellbore wall rather than from the action of the bit.

cavitation

The formation and subsequent collapse of vapor bubbles inside a centrifugal pump, often at the pump inlet, which sounds like marbles rattling around inside the pump.

cavity pump

A progressing cavity pump, which moves fluid in sealed cavities and tolerates solids and viscous oil.

CBM

Coalbed methane: natural gas, predominantly methane, generated during coal formation and held adsorbed on the surfaces of the coal.

CCGT (combined-cycle gas turbine)

A combined-cycle gas turbine plant, the standard modern gas-fired generating configuration.

ccl tool

The casing collar locator, used to set tool depth accurately against known collars.

CCSP (Certified Cloud Security Professional)

The ISC2 credential specific to cloud security.

CDP

Common depth point: the point on a reflector illuminated by several source-receiver pairs, whose traces are gathered and stacked together.

CEC

Cation exchange capacity: the quantity of positively charged ions a clay can hold on its negatively charged surfaces.

cell

A section of a forced-draft or induced-draft cooling tower that can be operated independently.

cell voltage

The voltage across a single cell of a battery or electrolyzer.

cellar

The excavated pit beneath the rig floor that houses the wellhead and gives room to work below the rotary.

cellophane

Flaked material added to bridge and seal loss zones while drilling.

cellulosic polymer

A water-soluble polymer made by chemically modifying natural cellulose, used mainly for filtration control.

Celsius

A temperature scale with the freezing point of water at O°C and the boiling point of water at 100°C.

cement

A viscous adhesive used to bond plastic fittings to plastic pipe in order to form leak-proof joints.

cement accelerator

An additive that shortens the thickening time and speeds strength development of a cement slurry.

cement additive

Any chemical or material blended into a cement slurry to change the properties of the slurry or of the set cement.

cement bond

Cement bond is a bond of cement between the exterior casing wall and the adjacent formation. Cement Bond Log (CBL) A cement bond log is a log that uses the variations in amplitude of an acoustic signal traveling down the casing wall between a transmitter and receiver to determine the quality of cement bond on the exterior casing wall.

cement bond log

A cement bond log documents an evaluation of the integrity of cement work performed on an oil or gas well.

cement bond log (CBL)

A cement bond log is a log that uses the variations in amplitude of an acoustic signal traveling down the casing wall between a transmitter and receiver to determine the quality of cement bond on the exterior casing wall.

cement dispersant

An additive that separates cement particles so the slurry flows more freely at the same water content.

cement evaluation log

A log assessing whether cement is present behind the pipe and bonded to both the casing and the formation.

cement extender

An additive or inert material that lowers slurry density or raises yield, so a given sack of cement fills more volume.

cement head

The fitting on the top casing joint that holds the cementing plugs and releases them into the string on command.

cement job

The operation of mixing and placing cement to seal the annulus.

cement plug

A column of cement set in the wellbore to isolate pressure, abandon a zone, or provide a base for a sidetrack.

cement retainer

A packer-type tool set in casing that lets cement be squeezed into a lower interval while isolating the annulus above.

cement retarder

An additive that lengthens thickening time so a slurry can be placed before it begins to set.

cement slurry

The pumpable cement mixture placed behind casing to seal the annulus.

cement squeeze

A remedial job forcing cement under pressure into a leak path, a channel or perforations behind the casing.

cementation

The precipitation of mineral cement between grains, binding loose sediment into rock — one phase of lithification.

cementation exponent

The exponent m applied to porosity in Archie's relation between formation factor and porosity.

cementation exponent or cementation factor

The exponent of porosity, m, in the relation of formation factor, F, to porosity, ϕ. In the Archie equation, F = 1/ϕᵐ.

cementation exponent, porosity exponent

The exponent of porosity, m, in the relation of formation factor, F, to porosity, ϕ. In the Archie equation, F = 1/ϕᵐ. H. Guyod termed m the cementation exponent because m was observed to be higher in cemented rock. Another term for this is the porosity exponent.

cementer

The crew member in charge of the cementing crew and its equipment at the wellsite.

cementing

Cementing is the process of placing cement outside of casing strings to cement the casing to the formation.

cementing engineer

The service company specialist who designs the slurry, supervises mixing and runs the cementing unit at the well.

cementing operation

Placing cement behind casing to seal and support it.

cementing plug

A rubber plug pumped ahead of and behind a cement slurry to keep it separated from the fluids on either side.

CEMF

Counter-electromotive Force: The electrical force produced by a motor as it turns; typically used as feedback to control the speed of a DC motor.

CEMTREC

The Chemical Transportation Emergency Center.

center of gravity

The point at which an object's weight is concentrated, or the single point on which an object could be balanced and not tip in any direction. For empty forklifts, it is generally just below the operator's seat; for symmetrical loads, it is at the middle of the load.

center tap

A tap that is connected to the electrical center of a winding.

centerline

The axis of a shaft or vessel, the reference alignment is measured from.

centimeter

A unit of length, used in metric core and log measurement.

centipoise

A unit of dynamic viscosity equal to one hundredth of a poise, symbol cP — water sits at about 1 cP at room temperature.

central message

The single idea the audience should retain if they remember nothing else.

centralization

Keeping casing central in the hole so cement fills the annulus evenly.

centralized

A centralized logging tool is one which is run in the center of the borehole.

centralized vs. decentralized function

Whether a capability is held at the center or distributed to business units.

centralizer

A device fitted around a pipe or tool string to hold it near the center of the wellbore.

centralizer, centralized

A centralizer is hardware to position equipment in the center (centralized) of a borehole.

centralizers

Devices holding casing central in the hole so cement can fill the annulus evenly.

centrifugal

Using rotation to move fluid or separate solids by density.

centrifugal compressor

A compressor raising pressure by accelerating gas and then decelerating it, smooth but surge-limited.

centrifugal fan

A fan that moves air by centrifugal action, that is, by spinning air outward from the center of the shaft; typically used to produce higher pressures than axial fans.

centrifugal force

An outward radial force that tends to impel or throw materials outward from a center of rotation.

centrifugal pump

A pump that uses centrifugal force to move liquid through a system.

centrifugal separator

A type of moisture separator that relies on centrifugal force to separate moisture from steam; also called a cyclone separator.

centrifuge

A device or instrument that uses centrifugal force to separate materials in a mixture into layers according to their different densities.

centrifuge test

A test to determine percentage of BS&W in oil samples. Same as shake-out or grind-out test.

centrifuge tube

The graduated tube a sample is spun in to read water and sediment content.

CERCLA

The Comprehensive Environmental Response, Compensation and Liability Act of 1980, the US law governing cleanup of contaminated sites.

cesium acetate

A very soluble salt used to make solids-free completion brines up to about 20 lb/gal without heavy metals.

cesium formate

A dense, near-neutral solids-free brine of caesium and formic acid, used where very high kill weight is needed without weighting solids.

cetane

The measure of how readily diesel ignites under compression.

cetane number

A measure of a diesel fuel's ignition quality, or how easily the fuel can be ignited by compression in an engine.

CFR (Cost and Freight)

As CIF but without insurance, which the buyer arranges.

CGBP (Certified Global Business Professional)

The credential covering global trade management, marketing, supply chain and finance.

chain hoist

A manual or powered hoist lifting on a chain.

chain tongs

A hand wrench that grips pipe with a chain wrapped round it, used for smaller threaded connections.

chalk

A soft, white, porous sedimentary rock; a form of limestone composed of the mineral calcite.

change agent

Someone who actively drives adoption, whether or not it is their formal role.

change control board

The body that assesses and approves changes to approved scope.

change leadership

Providing the direction and visible commitment that makes a change credible.

change management

The disciplined handling of the human side of a change so it is actually adopted.

Change Management Assessment

A diagnostic of readiness, capacity and likely resistance before a change begins.

Change Management Plan

The document setting out how a change will be communicated, supported and embedded.

Change Management Toolkit

The set of instruments a change practitioner uses across the phases of a change.

change request

The submission proposing a change and setting out its cost, schedule and risk consequences.

change resilience

The capacity of people and the organization to absorb repeated change without exhaustion.

channel

An elongate, usually concave-floored trough cut by flowing water, later filled by the sediment that the flow carried.

channel choice

Selecting the right medium — meeting, memo, presentation, conversation — for the message.

channel valve

A suction or discharge valve that has plates in channels which lift and seat by differential pressure to control gas flow. This valve is used for high pressure compression requirements.

channeling

A problem in which feed material does not flow evenly through a catalyst bed due to a buildup of carbon or scale on the catalyst.

channels

A channel is a device that carries data from the receivers to a recorder. In land work, this is typically a string or group of receivers that are connected to a cable which transmits the seismic data to a recorder. In marine work, the channels are built into the streamers, which are connected to the recorder in the vessel. In some modern, wireless systems, individual receiver units either record the data within the unit for later retrieval or they wirelessly transmit the data to a recorder.

chapter

A division of the NEC that contains information about a specific topic. The NEC has nine chapters.

character

The distinguishing shape of a seismic event — its waveform, frequency, phase and continuity taken together.

characteristic impedance

The impedance of an infinitely long length of transmission line.

characterization

The process by which an input or output is modified to improve the response of a process control loop.

characterizing business opportunities

Classifying prospects on commercial, technical and strategic criteria so they can be compared.

charge

The fundamental unit of electricity: the excess or deficiency of electrons in a body. In electrical formulas, charge is typically represented by a small q or a capital Q.

charge heater

A furnace in which crude is heated until its temperature is high enough for distillation to occur.

charge preparation

The process of preheating hydrocarbon feed streams prior to processing them in a cat cracking unit's riser; may also include treating the charge to reduce the effects of accumulated metals.

charge stream

The feedstream of hydrocarbons supplied to a cat cracker for processing.

charge tank

See Feed tank.

charge-coupled device

An integrated circuit containing an array of linked, or coupled, capacitors.

charged particle

A particle carrying electric charge.

charged zone

A formation that has been pressured up above its natural level by fluid injected or lost into it.

charging

The process of adding raw materials to a reactor.

charisma

Personal presence that draws others, distinct from competence.

charismatic leadership

Leading through personal magnetism, effective but dependent on the individual.

Charpy test

A notched-bar impact test measuring the energy a steel absorbs as it fractures, used to check toughness at a specified temperature.

chart of accounts

The structured list of every account the organization uses.

chart recorder

A device used to produce charts that provide information about process variables.

charter party

The contract between shipowner and charterer setting the terms of hire.

charterer

The party hiring the ship, whether for one voyage or a period.

chartering

Hiring a ship for a voyage or a period.

chassis ground

A ground within an oscilloscope, often to the chassis. A chassis ground is usually unable to dissipate large electrical currents.

chatbot

A system that converses with a user in text or speech, now usually built on a language model.

chattering

Rapid repeated opening and closing, which destroys valve seats and relay contacts.

check shot survey

A check shot survey is a type of borehole seismic data designed to measure the seismic travel time from the surface to a known depth. The compressional wave velocity of the formations in a wellbore can be measured directly by lowering a geophone to each formation of interest, sending out a source of energy from the surface and recording the resultant signal.

check valve

A valve designed to allow fluid or gas flow in only one direction and block flow in the opposite direction, protecting equipment and systems from backflow conditions.

checkshot

A measurement of seismic travel time to known depths in a well, used to calibrate velocity.

chelate

To bind a metal ion within a ring structure formed by a complexing agent, holding it in solution.

chelating agent

A chemical that binds a metal ion into a ring structure, holding it in solution so it cannot precipitate.

chelation

The equilibrium between a metal ion and a chelating agent that holds it in a soluble complex.

chemical barrel

A small mixing container on the rig, usually above the suction pit, through which liquid additives are metered into the mud system.

chemical compaction

Porosity loss by pressure solution rather than by mechanical grain rearrangement.

chemical cutter

A wireline tool that severs stuck pipe by directing a chemical reactant under high pressure to burn through the pipe wall.

chemical diversion

Using a viscous or particulate chemical to block the zones already taking fluid so the treatment goes into the rest.

chemical diverter

A chemical that temporarily blocks the zones taking most fluid, so the treatment spreads across the whole interval.

chemical equation

The written statement of a reaction's reactants and products.

chemical flooding

An enhanced oil recovery process injecting chemical solutions — polymer, surfactant or alkali — to improve displacement or sweep.

chemical hazard

A hazard arising from a substance's chemical properties.

chemical hygiene

The practices keeping laboratory chemical exposure within safe limits.

chemical hygiene officer

An employee who is designated by the employer, and who is qualified by training or experience, to provide technical guidance in the development and implementation of the provisions of the Chemical Hygiene Plan.

chemical hygiene plan

A written program developed and implemented by the employer that sets forth procedures, equipment, personal protective equipment, and work practices that 1. are capable of protecting employees from the health hazards presented by hazardous chemicals used in that particular workplace and 2. meet the requirements of paragraph (e) of the OSHA Lab Standard.

chemical injection

The continuous or intermittent delivery of treating chemicals into a well or a process stream.

chemical injector

The pump and fittings dosing a treatment chemical into the process.

chemical intermediate

A chemical that can be used to make other products.

chemical marker injection

Injecting a slug of chemical tracer into a flowing well and timing its passage to derive the flow rate.

chemical neutron source

A sealed capsule of two elements in contact whose reaction emits neutrons continuously, typically americium-beryllium.

chemical oxidation

A gas sweetening process whereby a solution is mixed with hydrogen sulfide to form a solid sulfur compound.

chemical oxygen demand

The oxygen required to oxidize the chemically oxidisable matter in a water sample, abbreviated COD.

chemical potential

The change in a system's Gibbs free energy when an infinitesimal amount of a component is added at constant pressure and temperature.

chemical sewer

An underground piping system designed to collect wastes or spilled chemicals and route them to devices such as retention ponds.

chemical wash

A thin, generally water-based fluid pumped ahead of cement to thin and disperse the mud it has to displace.

Chenevert method

The API electrohygrometer test measuring the water activity of an oil mud or of cuttings.

chert

A hard sedimentary rock of cryptocrystalline silica, also called chalcedony.

cherty

Containing chert.

chief human resources officer (CHRO)

The executive accountable for people strategy across the organization.

chiller

Exchanger cooling process fluid with a refrigerant boiling on the other side.

chisel

A hand tool with a cutting edge driven by impact.

chlorides

Chemicals that are injected into a reforming process in order to promote the isomerization and hydrocracking reactions.

chloridization

Step in catalyst regeneration in which chlorides are restored to the surface of the catalyst after the primary and secondary burns.

chlorinator

The equipment dosing chlorine into water.

chlorine

Chlorine is a chemical element with the symbol Cl and atomic number 17.

chlorine gas

A toxic yellow-green gas used for disinfection and in chemical manufacture.

chlorite

A platy green sheet-silicate clay mineral, common in sedimentary and low-grade metamorphic rocks.

choke

A device with a restricting orifice used to control flow rate or the pressure downstream of it.

choke line

The high-pressure line from an outlet on the BOP stack to the choke manifold, carrying returns during a well control operation.

choke manifold

The arrangement of high-pressure valves and piping, including at least two adjustable chokes, through which a kicking well is circulated.

choke valve

Valve deliberately restricting flow to set rate or drop pressure, rather than to isolate.

chokepoint

A narrow waterway whose closure would disrupt a large share of world oil movement.

chop mode control

A vertical control that allows an oscilloscope to display two low-frequency signals, usually under 20 kilohertz, simultaneously. This is done by chopping up and displaying segments of both signals.

chopper

A rapid switching circuit typically used in small DC controllers and in some older-style AC inverter controllers.

choppy vs. complex sentence

Sentences too short to connect ideas against sentences too long to follow.

CHOPS

Cold heavy oil production with sand: producing viscous oil without heat, by deliberately allowing formation sand to flow with it.

Christmas tree

The assembly of valves, chokes, spools and fittings on top of a completed well that controls and directs the flow of produced fluids.

chromate salt

A salt containing chromium in the plus-6 state, such as potassium chromate, used as a corrosion inhibitor.

chromatogram

An X-Y graph that shows the results of a chromatographic analysis.

chromatograph

An analytical device that separates the components in a multi-component mixture according to how easily the components pass through a separation column, often used to measure the concentration of various gases in a complex gas mixture.

chromatography

A separation technique for separating a mixture by passing it in solution or suspension through a medium in which the components move at different rates based on their interaction with a stationary material held inside a column.

chromatography column

The column separating a sample into its components as the carrier sweeps it through.

chromatography system

The analyzer separating a sample into components on a column before detecting them.

chrome lignite

Lignite reacted with a chromium salt to improve its thermal stability as a filtration control additive and thinner.

chrome lignosulfonate

Lignosulfonate reacted with chromium to improve its temperature stability as a mud deflocculant, abbreviated CLS.

chrome tubing

Tubing made from an alloy containing a high proportion of chromium, typically 13% or more, for corrosion resistance.

chrome-free

Describing a mud additive, usually a lignosulfonate or lignite, that contains no chromium compounds.

chromic salt

A salt containing chromium in the plus-3 state, such as chromic chloride.

chronic

Lasting for a long period of time or marked by frequent recurrence. A chronic condition is usually defined as one lasting three months or more.

chronic effects

Effects that develop after prolonged or repeated exposure to a hazardous chemical over a period of time.

chronic health effect

An adverse health effect that occurs after repeated or long-term exposure to a health hazard, which may not appear until months or years after exposure and may have a long duration.

chronic health effects

Health problems that occur only after repeated or longduration exposure to a chemical, or health effects that may develop after a long period of time.

chronometers

Chronometer refers to any method or tool used to accurately measure the age of a rock or fossil; essentially acting as a "timekeeper" for geological events.

chronostratigraphic

Chronostratigraphy is the study of the age and relative time relationships of rock strata in Earth's history with the goal of reconstructing past events (by correlating the ages of rocks around the world) to determine the depositional environments in which rocks were deposited.

chronostratigraphic chart

A chart plotting stratigraphic units against geological time, showing what was deposited when and where the gaps are.

chronostratigraphy

The description and classification of strata by age.

chuck

A device with internal jaws that grip the shank of a drill bit or other attachment and hold the bit or attachment in a power drill or other power tools.

chuck key

A device used to tighten or loosen the jaws of a chuck.

churn flow

The transitional multiphase regime in near-vertical pipe where slugs break down and the flow becomes chaotic, with gas taking over as the continuous phase.

CI

Contour interval — the constant difference in value between adjacent contours on a map.

CIF (Cost, Insurance and Freight)

The seller arranges and pays for carriage and insurance to the destination port.

cipher

The algorithm performing the encryption.

circle

A closed curved line around a center point.

circle shooting

Marine acquisition in which the vessel sails a circular or coil path so every azimuth is recorded, abbreviated in full-azimuth work.

circuit

A complete path for current flow that connects an electrical source to equipment, including a voltage source and resistance.

circuit breaker

A protective device that can be opened manually or automatically to protect a circuit from excessive current, providing a means of isolating loads from a source of electrical power. It can be reset after tripping.

circuit loading

The unintentional interaction of a probe and an oscilloscope with the circuit being tested, which distorts the signal.

circuit voltage

The voltage present in a circuit.

circular chart

A chart made on a circle of paper that can be used to show operating conditions over a period of time.

circular mil

The area of a circle with a diameter of 1 mil (0.001 inches).

circular mil system

A system used to indicate the size of wires; sizes range from 250,000 circular mils (smallest) to 2,000,000 circular mils (largest).

circular saw

A power saw that has a disc-shaped, circular blade. The cutting edge of the blade is along the circumference of the blade. Also called a Skilsaw, a cutoff saw, a utility saw, or a builder's saw.

circulate

To pump fluid around the complete active system — down the string, up the annulus and back through the surface tanks.

circulate out

To pump until fluid or material from a given depth has been brought all the way to surface.

circulating heat medium

Oil or glycol carrying heat from a heater to users, avoiding fired heat on process streams.

circulating pump

The pump maintaining flow round a loop.

circulating system

The pumps, lines and solids-control equipment moving drilling fluid round the well.

circulating water

Water pumped round a closed loop to carry heat.

circulating water pump

The pump moving water round a cooling loop.

circulating water system

The system pumping water round a cooling or heating loop.

circulation

The movement of fluid around the complete active system, from surface tanks through the well and back.

circulation device

A completion component near the packer that can be opened to connect the tubing with the annulus.

circulation loss

The loss of whole mud into a formation instead of returning to surface.

circulation pump

Pump maintaining flow round a closed loop against friction only, not against static head.

circulation rate

The volume a loop moves per unit time, set to match absorption or heat duty rather than pump capacity.

circulation sub

A downhole sub with ports that can be opened to establish circulation at a point in the string.

circulation system

The complete circuit the drilling fluid travels — pumps, standpipe, string, bit, annulus, solids control and tanks.

circulation time

The time mud takes to travel from the suction pit, down the well and back to surface.

circulation valve

A downhole valve that opens communication between the string and the annulus so the well can be circulated.

circumference

The distance around the curved line that forms a circle.

cirrhosis

A disease of the liver in which normal liver cells are damaged and replaced by scar tissue, decreasing the amount of normal liver tissue. The scar tissue interferes with the flow of blood through the liver, and the loss of normal liver tissue leads to loss of liver function.

CISSP

The senior information security credential, requiring both an exam and verified experience.

citric acid

A weak organic tricarboxylic acid used in acid treatments as an iron control agent and chelating agent.

city gate

The station where gas passes from a transmission line to a local distribution system, metered and reduced in pressure.

civil law

A legal tradition where codified statute governs and judicial decisions do not bind future cases.

clamp

A fastener that binds or presses parts together.

clapper

The hinged closure member in a swing check valve.

clapper element

A relay element that operates when an electromagnetic field attracts a hinged plate to close contacts.

clarification

A process used to remove suspended solids from water or wastewater, typically by adding chemicals to cause small particles to clump together and settle out.

clarifier

A vessel or tank that, with the aid of chemicals, promotes the natural settling out (sedimentation) of solid particles and/or bacteria from wastewater or other liquids.

clarity

A measure of how clear, or transparent, a substance is.

class A fire

A classification for fires that involve wood, paper, rags, or other similar materials.

class B fire

A classification for fires that are caused by chemicals or flammable liquids.

class C fire

A classification for electrical fires.

class D fire

A classification for fires that involve flammable metals such as magnesium and phosphorous.

classical reservoir modeling

Mapping reservoir properties as two-dimensional layer maps rather than as a three-dimensional cell model.

clast

A clast is a fragment of rock or mineral that breaks off from an existing rock through physical weathering. Clasts have a wide size range, from less than a micron to the size of an apartment building.

clastic intrusion

A body of sediment injected into surrounding rock while still fluidized, also called an injectite.

clastic rock

Rock built from transported fragments of older rock.

clastic rock formations

Clastic rocks are composed of fragments (clasts) of pre-existing minerals and rock. These clasts break off existing rocks and minerals and, through forces of nature (erosion, wind, rain, etc.) form new rocks.

clastic rocks

Rocks composed of small fragments (clasts) of other rocks, which determine the composition and texture of the clastic rock.

clastic rocks, clastics, clastic

Clastic rocks are rocks which are composed of small fragments of other rocks. These fragments, known as clasts, determine the composition and texture of the clastic rock.

clastic sediment

Sediment made of fragments broken from pre-existing rock, transported and redeposited.

clastic sedimentary rock

Rock formed of transported particles, the setting of most sandstone reservoirs.

clasts

A clast is a fragment of rock or mineral debris that has been broken off of a larger rock through physical weathering.

clathrate

A structure in which molecules of one substance are caged within a crystal lattice formed by another — for natural gas, methane trapped in a water-ice cage.

Claus reaction

A sulfur recovery reaction in which a portion of H₂S is burned to produce SO₂, and the two are combined to produce sulfur and water.

clay

A fine-grained rock that combines one or more clay minerals with traces of metal oxides and organic matter. Clays are plastic due to their water content and become hard, brittle, and non-plastic upon drying.

clay extender

A polymer that increases the yield of a drilling clay, so less clay gives the same viscosity.

clay fines

Clay fines are very small clay particles in the size range 44 to 74 microns.

clay lamination

A thin clay layer within a sand, which cuts vertical permeability far more than porosity.

clay mineral

A fine platy mineral whose swelling and surface chemistry affect both drilling and log response.

clay particle

A platy mineral particle of clay size, whose surface charge holds water and conducts current.

clay porosity

Clays have high porosities due to the structured nature of clay minerals. They can hold a large volume of liquids per volume of bulk material, but they do not release liquids rapidly and therefore have low hydraulic conductivity.

clay sheets

Clay sheets are comprised of a stack of two, or three, layers of aluminum octahedra or silica tetrahedra lattices.

clay stabilizer

A stimulation additive that prevents clay in the formation from swelling or migrating when it meets a water-based fluid.

clay swelling

Formation damage in which clay takes up water, expands and reduces permeability.

clay-bound water

Water within the clay lattice or near the surface within the electrical double layer. This water does not move when fluid is flowed through the rock.

clay-water interaction

The whole set of processes by which clay minerals take up water — surface hydration, interlayer swelling and osmotic expansion.

clean

Describing a sedimentary rock, such as sandstone or limestone, containing only minimal clay.

clean air act

An Environmental Protection Agency regulation that identifies a number of potentially hazardous pollutants and sets limits on the amounts of these pollutants that can be emitted.

clean formation

A formation with no significant shale content.

clean out

To remove fill, sand, scale or debris from the wellbore so it is back to full bore.

clean sand

Clean sand refers to sandstone with a minimal amount of silt and clay matrix, meaning the sand grains are primarily composed of quartz with very little other material mixed in; essentially a "pure" sandstone.

clean sandstone

Sandstone with little clay, giving good porosity and unambiguous logs.

clean tanker

A tanker carrying refined products, whose tanks must be kept free of heavy residues.

cleanup

A period of controlled production after a treatment, during which the treating fluids are recovered from the formation.

clear brine

A solids-free salt solution used as a completion or workover fluid, weighted by dissolved salt rather than by suspended particles.

clear-water drilling

Drilling with a water-base fluid carrying almost no solids, relying on flow rate rather than viscosity to clean the hole.

clearance pocket

A device which allows adjustment of a compressor's capacity. It can be a fixed-volume or variable-volume pocket.

clearance volume

The volume remaining in the cylinder when the piston is at the end of its stroke.

clearances

The spaces around a variable speed controller required for proper cooling during normal operation.

clearinghouse

The body standing between counterparties on an exchange, removing bilateral credit risk.

cleartext and ciphertext

The readable message and its encrypted form.

clevis

A U-shaped connector closed by a bolt or pin through its ends, used to couple rigging components.

clinker grinder

A device that uses heavy metal rollers to crush large chunks of bottom ash into smaller particles.

clinoforms

The inclined depositional surfaces built as sediment progrades into deeper water.

clockwise direction

Turning in the direction of a clock's hands.

clog

Block by accumulated solids, usually where velocity falls below what keeps them moving.

close-out document

The record completing the project, including final accounts and lessons learned.

closed heater

A heater that typically uses a shell and tube design to keep steam separated from condensate or feedwater.

closed impeller

An impeller whose vanes are enclosed by shrouds on both sides.

closed loop

An automatic process control system in which the input device, controller, and output device are connected so that they form a closed circuit with feedback, where the signal is fed back from the output to the input and then back to the output.

closed loop gain

The gain of an op amp circuit.

closed mud system

A drilling fluid system in which nothing is discharged but the drilled cuttings themselves, the fluid being cleaned and reused.

closed-chamber testing

A drillstem test run with the surface valve shut, so the string above the tool forms a chamber of known volume that the formation flows into.

closed-in well

A well shut in at a valve so that it is not producing.

closing

Formally finishing the project, releasing resources and capturing lessons.

closing and implementing a deal

Converting agreement into documented, executed commitments.

closing gauge

Measurement of oil level in lease tank following a transfer or run. May be called bottom gauge.

closing unit

The hydraulic power pack and accumulator bank that operates the blowout preventer stack.

closure

Closure occurs when the displacements determined between each adjacent pair of curves, taken cylindrically (1-2, 2-3, 3-4, 4-1), have an algebraic sum of zero.

closure pressure

The pressure at which a hydraulic fracture closes when no proppant holds it open — effectively the minimum in-situ stress.

cloud computing

Computing resources provided on demand over a network rather than owned and operated locally.

cloud data lifecycle

The stages cloud-held data passes through, from creation to destruction.

cloud point

The temperature at which wax crystals begin to form in a fuel.

cloud point glycol

A glycol that dissolves in water when cool and separates into micelles above its cloud point temperature.

Cloud Security Alliance

The body publishing cloud security guidance and the CCSK credential.

cloud service category

Infrastructure, platform or software as a service, differing in how much the provider manages.

cloud service provider (CSP)

A company selling computing, storage and software as a metered service over the internet.

cloud service provider vs. cloud consumer

The party supplying the service against the party using it.

clumps

Aggregated particles, which must be dispersed for a fluid to perform properly.

cluster

A group of wells drilled from one location or tied back to one subsea manifold.

cluster analysis

Cluster analysis, or clustering, is the task of grouping a set of objects in such a way that objects in the same group are more similar to each other than to those in other groups.

clustering

Clustering means that, if at any level in the well, the majority of the possible dips agree with each other and agree with the majority of the dips at adjacent levels in the well, then those are the most probable dips to use.

clutch key

A rectangular piece of metal that transfers rotation from one component of gear train to another.

CMC

Carboxymethylcellulose: an anionic cellulose polymer used in drilling fluids for filtration control.

CMC-Hi Vis

The high viscosity grade of carboxymethylcellulose, another designation for CMC-HVT.

CMC-HVT

High viscosity technical grade carboxymethylcellulose, giving both filtration control and viscosity in a water-base mud.

CMC-Lo Vis

The low viscosity grade of carboxymethylcellulose, another designation for CMC-LVT.

CMC-LVT

Low viscosity technical grade carboxymethylcellulose, used for filtration control with minimal effect on viscosity.

cmhec

Carboxymethyl hydroxyethyl cellulose, a polymer used in cement and drilling fluids.

CMP

Common midpoint: the surface point halfway between source and receiver, shared by many source-receiver pairs whose traces are sorted and stacked together.

cmp gather

The traces sharing a common midpoint, gathered for velocity analysis and stacking.

cmp interval

The spacing between common-midpoint positions, which sets horizontal sampling of the stack.

CMS online

IHRDC's proprietary competency management software.

co-rendering

Co-rendering is an interpretation aid that assigns different attributes to display parameters, such as hue, intensity and saturation, so that they all contribute to the final color display.

CO2 enhanced oil recovery

Injecting carbon dioxide to swell and thin the oil so more of it flows to the wells.

CO2 injection

An enhanced oil recovery method in which carbon dioxide is injected into a reservoir to swell and mobilize the oil and improve displacement.

CO2e (carbon dioxide equivalent)

A common unit expressing other greenhouse gases as the amount of carbon dioxide with equal warming effect.

coach

A person (usually a lead technician) who checks on progress and provides support to an assessment candidate (employee) as appropriate.

coaching

coagulation

The first step of clarification, in which chemicals are added to water to form sticky masses that cause small, suspended solids to combine into larger clumps.

coal

A carbon-rich sedimentary rock formed from plant remains laid down as peat in swamps and then buried.

coal bed methane (CBM)

Natural gas extracted from coal beds.

coal bed methane (CBM), also termed coal seam gas (CSG)

Natural gas, usually primarily methane, contained in coal deposits, whether or not stored in the gaseous phase.

coal feeder

The equipment metering coal to the pulverizer or furnace.

coal gasification

The partial oxidation of coal at high temperature to produce a synthesis gas of hydrogen and carbon monoxide.

coal seam

A bed of coal, which can be both a source rock and, fractured, a gas reservoir.

coal seam gas

Methane generated during coal formation and held adsorbed in the seam — the Australian term for coalbed methane.

coal-fired boiler

A boiler burning coal, needing pulverizing, ash handling and flue gas cleaning.

coalesce

Combining of water droplets into larger droplets so they will settle out of oil.

coalescence

The merging of small droplets into larger ones when they touch, the reverse of dispersion.

coalescer/filter

Filter combining fine droplets into larger ones so gravity can remove them.

coalescing

Small droplets merging into larger ones, the mechanism by which emulsions are broken.

coarse

In the strict API sense, describing any particle larger than 2,000 microns.

coarse measurement tools

Measurement tools that are reasonably accurate to between 1/64 inch and 1/100 inch (English).

coarsening-upward

A sequence with grain size increasing upward, typical of prograding deltas.

coating

A thin applied film — liquid or powder — that forms a continuous barrier over a structure to protect it from corrosion.

coating flaw

A break or defect in a pipeline's protective coating, exposing bare steel to the surrounding soil or water.

coax

A cable with two concentric conductors separated by an insulator. Commonly used for PLC network connections.

coaxial cable

A type of cable that has one conductor in the middle and one surrounding it in the form of a sheath. Coaxial cable can carry very high frequencies long distances with little attenuation.

code of conduct

The rules setting out what behavior the organization requires.

code of ethics

The statement of values from which those rules derive.

COFCAW

Combination of forward combustion and waterflooding — in-situ combustion with water injected to carry heat forward from behind the burn front.

cogeneration

Producing two or more useful forms of energy — typically power and heat — from a single fuel input.

cognitive computing

A marketing term for AI systems presented as reasoning in a human-like way.

coherence

A measure of how similar a seismic waveform is from trace to trace.

coherence filtering

Processing that enhances events consistent from trace to trace and suppresses those that are not.

coherence map

A map of how similar each seismic trace is to its neighbors, which makes faults and channel edges stand out as low-coherence lineaments.

coherence vector map

A map of trace-to-trace similarity across a 3D volume, on which faults and channel edges appear as low-coherence lineaments.

coherent

Describing seismic events that maintain continuity of phase from trace to trace.

coherent detection

Detecting a signal by exploiting its consistency across channels, against noise that is not consistent.

coherent noise

Unwanted seismic energy that holds consistent phase from trace to trace — ground roll, multiples and scattered arrivals.

cohesive force

A molecular force that exists between like molecules.

coil

In ladder diagrams, the part of an output device that moves the switch contact.

coil wire

The insulated wire wound to form a coil.

coiled tubing

A long, continuous length of metal pipe, normally 1" to 3.25" in diameter, wound on a spool or large reel for easy transport and storage. It is straightened prior to pushing into a wellbore and is used for well interventions, well repair or workover activities, and sometimes as production tubing. Coiled tubing is often used to run well logs.

coiled tubing completion

A completion using coiled tubing as the production conduit, or as the means of conveying and installing completion equipment.

coiled tubing connector

The downhole device joining the tool string to the end of the coiled tubing.

coiled tubing drilling

Drilling with coiled tubing and a downhole mud motor turning the bit, since the tubing itself cannot rotate.

coiled tubing string

A continuous length of low-alloy carbon steel tubing, spooled on a reel for transport and run into the well without making connections.

coiled tubing unit

The complete package of surface equipment needed to run coiled tubing — reel, injector head, control cabin, power pack and pressure control stack.

coke

Carbon deposits, consisting of carbon, hydrogen, and sulfur, that can build up on a catalyst.

coke deposit

Carbon laid down on tubes or catalyst, which insulates, blocks and deactivates.

coking

The accumulation of carbon deposits on the inside walls of furnace tubes, which can restrict fluid flow and cause heat transfer problems.

coking refinery

A refinery with a coker, able to convert the heaviest residue into lighter products.

coking unit

A unit that produces sponge coke by heating the pitch, or bottoms, from the residuum fraction to crack the remains.

cokriging

Kriging that estimates one regionalized variable using a second, more densely sampled one correlated with it.

cold filter plugging point (CFPP)

The temperature at which wax blocks a fuel filter, the practical cold-weather diesel limit.

cold flow

Cold flow is compression-induced wireline cable deformation.

cold heavy oil production with sand

Producing viscous oil without heat by deliberately allowing formation sand to flow with it.

cold production

Any non-thermal primary method of producing heavy oil, including horizontal wells and sand co-production.

cold separator

Separator operating at low temperature to drop out liquids that would otherwise stay in the gas.

cold startup

The startup of a boiler that has been out of service for an extended period of time, which has allowed metal components to cool down to room temperature.

cold work

Any work that does not involve a source of ignition.

collaborative communication

Communicating to reach a shared outcome rather than to win the exchange.

collaborative learning

Learners working together, where explaining to a peer is part of the mechanism.

collapse pressure

The external-to-internal differential pressure at which a tube or vessel deforms catastrophically inward.

collapsed height

The distance from the floor to the top of the mast of a forklift when the forks and the mast are fully lowered.

collar

A threaded coupling joining two lengths of pipe such as casing, liner or production tubing.

collar locator

A downhole tool that detects casing or tubing collars magnetically, providing depth references for correlation.

collar locator ccl

A tool detecting casing collars, used to position tools accurately by depth.

collar lock

A lock set into the recess of a tubing collar to anchor a tool or plug at a chosen depth.

collar log

A log showing the depth and relative position of casing or tubing collars, used to correlate depth for perforating and isolation work.

collective bargaining

Negotiation between an employer and a union over terms of employment.

collector

One element of a transistor. In a bi-polar transistor, the collector is one of the poles.

collision

The convergence of two lithospheric plates, producing mountain belts and, where oceanic crust is consumed, subduction zones.

colloid

Finely divided solid dispersed through a liquid, small enough not to settle under gravity but large enough to scatter a light beam.

colloid, colloidal

A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance.

colloidal

Describing material finely enough divided to stay dispersed in a liquid without settling, while still scattering light.

colloidal solids

Particles smaller than about 2 microns, which stay suspended indefinitely and carry surface charge — in a mud, the clays.

colloidal suspension

A dispersion of particles fine enough that Brownian motion and surface charge keep them from settling.

color bar label

A labelling system that uses color-coded sections to rate the health hazards, flammability, and physical hazards for a chemical and indicates appropriate personal protective equipment. Officially called a Hazardous Material Identification System (HMIS) color bar label.

color intensity

The strength of a particular color.

colorimeter

An analyzer that measures the color intensity of a solution.

Colpitts oscillator

An LC oscillator that produces a sinusoidal wave. The tuned circuit has two capacitors connected in series with a tap between them.

column

The part of a chromatograph where the components in a sample mixture are separated.

column flooding

Liquid backing up in a column because upward gas will not let it drain, at which point separation stops.

combi BOP

A preventer whose ram sets each combine two functions, such as blind and shear, or pipe and slip.

combinable magnetic resonance (CMR)

Combinable magnetic resonance (CMR) logging is a proprietary nuclear magnetic resonance (NMR) service developed by Schlumberger.

combination coupling

A type of fitting that is used to join two different types of conduit together.

combination string

A casing or tubing string made up of more than one size or weight of pipe.

combinational logic circuit

A logic circuit whose output depends only on its present inputs, with no memory.

combined operations

Calculations that include more than one type of mathematical operation.

combined-cycle gas turbine

A plant recovering turbine exhaust heat to drive a steam cycle, raising efficiency well above simple cycle.

combust

To burn, releasing heat and combustion products.

combustible

Capable of burning, and so requiring control of ignition sources.

combustible liquid

Any liquid having a flashpoint at or above 100°F (37.8°C) but below 200°F (93.3°C), except any mixture having components with flashpoints of 200°F or higher that make up 99% or more of the total volume.

combustible material

A material that can be ignited and can fuel a fire, but does not ignite as easily or burn as rapidly as a flammable material.

combustibles analyzer

An analyzer used to measure the concentration of combustible gases in an area.

combustion

A heat-producing chemical reaction that occurs when fuel, oxygen, and heat are combined.

combustion air

Air supplied to burn fuel.

combustion air system

The system that supplies the air necessary for the proper combustion of fuel in a boiler.

combustion area

The zone in which fuel burns.

combustion chamber

The enclosure in which fuel is burned in an engine or turbine.

combustion gas

Gas produced by burning fuel.

combustion system

The burner, chamber and controls firing a fuel, and what has to change to run on hydrogen.

come out of the hole

To pull the string out of the well.

come-along

A Lifting device operated by a handle on a ratchet; also called a ratchet lift.

command trailer

The instrumented cabin from which a fracturing treatment is monitored and controlled.

commercial bank debt

Loans from banks, more flexible than bonds but usually shorter and more tightly covenanted.

commercial discovery

A discovery large and productive enough to justify the cost of developing it.

commercial rate

A production rate high enough for the project to pay back its costs and meet the operator's economic threshold.

commercial viability

Whether a technology sells at a profit at scale, a later test than technical feasibility.

commerciality

Whether a discovery can be developed at a profit.

commingled

Produced from more than one zone or field through a single stream.

commingled completion

A completion producing two or more separate reservoir zones together into one conduit.

commingled flow

Flow in which production from two or more zones or laterals is mixed in a single conduit rather than kept separate.

commitment

A statement binding oneself to a position, which gains leverage and forfeits flexibility.

commodity exchange

The regulated venue on which standardized futures contracts trade.

commodity price

The market price of a standardized traded good.

commodity price cycle

The recurring swing from investment through oversupply to price collapse and underinvestment.

commodity pricing

Pricing driven by a market rather than negotiated with an individual supplier.

common chain

A type of chain used in rigging that consists of interlocked welded links of forged steel.

common depth point

The point on a reflector shared by several source-receiver pairs, valid as a single point only where beds do not dip.

common emitter amplifier

An amplifier circuit in which the input signal is applied to the base, the output signal is taken from the collector, and the emitter is common to both the input and the output.

common law

A legal tradition where decided cases bind later courts and build the law incrementally.

common midpoint

The surface point halfway between source and receiver, shared by many source-receiver pairs whose traces are gathered and stacked.

common midpoint method

Recording many source-receiver pairs that share the same midpoint and stacking them, so signal adds and noise partly cancels, abbreviated CMP.

common mode choke

A device used to reduce electrical noise in the cabling connecting a variable speed controller and its motor.

common mode rejection

A characteristic of op amp circuits: with any two equal voltages applied to the input terminals, the circuit will have an output of 0 volts. That voltage is known as the common mode voltage.

common negotiation mistakes

The recurring errors: no preparation, no alternative, conceding too early, ignoring interests.

common offset

Describing traces sharing the same source-receiver distance, gathered together for display or processing.

common point

See Signal common.

common receiver

Describing traces recorded at one receiver from a number of different sources.

common receiver gather

A display of the seismic traces that share a single receiver.

common reflection point

The point on the reflector at target depth from which the reflections in a gather actually come.

common source

Describing traces recorded at many receivers from a single source — a shot record.

common source gather

A display of the seismic traces that share a single source.

common vulnerabilities and exposures

The public catalog of known software vulnerabilities, each with a reference identifier.

common-mode input capacitance

Input capacitance a common-mode source would see to ground.

common-mode input impedance

The parallel sum of the small-signal impedance between each input terminal and ground.

common-mode input voltage

The average voltage at the input pins.

common-mode rejection ratio

The ratio of differential voltage amplification to common-mode voltage amplification, measured by determining the ratio of a change in input common-mode voltage to the resulting change in input offset voltage.

communicating up vs. down

Addressing senior audiences against addressing one's own team, which need different framing.

communication channel

A pathway for sending and receiving transfer trip signals.

communication model

The representation of that sequence, including noise and feedback.

communications process

The sequence by which a message is formed, sent, received and understood.

communitization

The combining of federal or state tracts into a unit large enough to satisfy spacing rules, the government-land counterpart of pooling.

community coalition

Several communities acting together, which raises their leverage and changes the negotiation.

community relations

The sustained work of maintaining a project's standing with the people who live around it.

commutative

Changing the order of the inputs does not change the result of the operation.

commutator

The electrical connection in a DC motor between the brushes and the armature windings; a metal ring that changes alternating current to direct current.

commutator segment

One of the copper bars a direct current machine's brushes run on.

compaction

The reduction of pore space as overburden packs grains closer together, consolidating sediment into rock.

compaction correction

An adjustment applied to sonic-derived porosity in shallow, undercompacted formations, where transit time overstates porosity.

compaction trend, sediment compaction trend

The compaction trend is the increasing density of formation rocks with their burial. As layers are piled one upon another, the sediments beneath are buried. The weight of these layers compacts the sediment grains.

company loyalty

The duty owed to the employer, and its limits when conduct is wrong.

company man

The operator's representative at the wellsite, who directs the work and makes the operator's decisions.

company representative

The operator's representative at the wellsite, responsible for decisions on the operator's behalf.

comparator

An op amp circuit that is used to compare voltages in order to determine which has a greater value.

compartment

A productive segment of a field that is not in pressure communication with the rest of it.

compartmentalization

The segmentation of a once-continuous reservoir into isolated compartments by faults, facies changes or diagenesis.

compass

A navigational instrument for determining direction relative to the Earth's magnetic poles. It consists of a magnetized pointer (usually marked on the North end) free to align itself with Earth's magnetic field.

compatible scales

Log scales chosen so that two curves overlay exactly under a defined condition, making departures visible at a glance.

compensated density log

A density log using two or more detectors at different spacings, so the effect of mud and mudcake can be removed from the reading.

compensated neutron

A neutron log using two detectors so borehole effects largely cancel.

compensated neutron log

The compensated neutron log tool makes thermal and epithermal neutron measurements to calculate porosity and identify lithology and the presence of gas.

compensation

A probe adjustment for passive probes that balances the capacitance of the probe with the capacitance of an oscilloscope.

compensation component

Any component used in an op amp circuit to compensate for the op amp's less-than-ideal characteristics. The components may be in side the chip or external to the chip.

compensation system

The whole structure of pay, benefits and incentives and the logic connecting them.

competence

The ability to perform activities to required standards.

competency

The combination of awareness, knowledge, skills and experience that enables performance to the required standard in the job, that is, what workers should know and do to perform their jobs safely and effectively.

competency assessment

Judging an individual against the defined standard, usually on evidence of performance.

competency assurance

Verifying that people doing safety-critical work remain able to do it, not merely that they were trained.

competency development plan [formerly learning plan]

Identifies the training needed to fill prioritized gaps between the employee's current skills and those required of the position, including the training type and expected time required to fill the requirement.

competency framework

The organizing scheme that groups competencies across roles and levels.

competency library

competency management system (CMS)

A process that assesses an employee's skills against those required in the job, and then develops a Competency Development Plan to prioritize and close any skill gaps identified.

competency model

The structured list of what someone in a role must be able to do, and to what standard.

competency model (CM) or job competency model (JCM)

competency role

A set of tasks and responsibilities related to one aspect of a jobholder's job that the jobholder is required to know and have the skills to perform. One or more competency role may be linked to a job title for the assessment process.

competency role builder (CRB)

A feature of CMS Online, accessible from Content Development on the left navigation menu. CMS Online uses the concept of roles for the development of competency models. One or more competency role can be linked to a single job title, or assigned directly to an employee. They can be built as a group, as well as for the individual roles within a family.

competency role family (CRF)

A group of jobs that involve similar work and require similar training, skills and knowledge, but at different levels of expertise. The family is based on function and not organizational structure.

competency specialist

competency unit (CU)

A combination of a general statement and a series of specific statements covering four levels of performance or proficiency. These statements contain the specific responsibilities, tasks and skills identified for each competency.

competency-based approach

Managing people against demonstrated ability to perform tasks rather than against qualifications or time served.

competent

Describing a bed strong enough to keep its original thickness through deformation, rather than flowing into the fold hinges.

competing interests

Objectives that cannot all be satisfied, which negotiation must rank rather than deny.

competitive advantage

The durable reason a company outperforms rivals, which imitation cannot quickly erode.

competitive bidding

Awarding work or acreage by inviting rival offers.

competitive positioning

Where a company stands against rivals on the dimensions customers actually value.

complementation

Logic inversion.

complete a well

To carry out the final stages of well construction that prepare the well to produce.

complete combustion

Burning fuel fully to carbon dioxide and water, with no unburned carbon left.

completion

The process of making a well ready for production or injection after drilling operations, which involves installing permanent equipment such as a wellhead and often includes hydraulic fracturing.

completion fluid

A solids-free liquid, usually a brine, used in the well during completion so that nothing is left behind to damage the formation.

completion guarantee

The sponsors' undertaking to see the project built and working before lenders take project risk alone.

completion interval

Completion interval is the reservoir interval that is open to the borehole and connected to the surface facilities for production or injection.

completion quality (CQ)

A prediction of how effectively a given rock interval will respond to hydraulic fracturing.

completion skin

The part of the total skin caused by the completion itself — perforations, gravel pack, partial penetration and deviation.

completion, well completion

A completion is an operation on an oil and gas well to open up the reservoir to production.

complex refinery

A refinery with conversion units able to turn heavy crude into light products.

complex trace analysis

Deriving instantaneous seismic attributes — reflection strength, phase and frequency — by forming the analytic trace with a Hilbert transform.

complexity refinery

The measure of how much conversion capacity a refinery has relative to its distillation.

compliance

compliance monitoring

Ongoing verification that operations meet legal and internal requirements.

composite frac tree

A frac tree with several valves machined into one body rather than stacked as separate spools.

composite sample

A sample built from portions taken over a period, representing the average rather than an instant.

composite sample container

The vessel a composite sample is accumulated in, kept at pressure for liquids.

composite stream

A production stream carrying more than one fluid — oil, gas and water together.

compositional

Based on individual component fractions rather than on lumped average properties.

compositional fluid analysis

Laboratory or downhole determination of what a reservoir fluid is made of, component by component.

compound annual growth rate (CAGR)

The average year-over-year growth rate of a metric over a specific period of time.

compound motor

A DC motor that contains two different types of fields: a series field, which is connected in series with the armature, and a shunt field, which is connected in parallel with the armature.

compounding and discounting

Moving money forward in time and back again at a given rate.

compressed air

Air raised in pressure for instruments, tools and utilities.

compressed gas

A gas or mixture of gases having, in a container, an absolute pressure exceeding 40 psi at 70°F, or exceeding 104 psi at 130°F, or a liquid having a vapor pressure exceeding 40 psi at 100°F.

compressed gas cylinder

Steel cylinders that contain compressed gases such as oxygen and acetylene. Also called bottles.

compressed gas system

The equipment generating, storing and distributing compressed gas.

compressed workweek

Full-time hours worked over fewer, longer days.

compressibility

The fractional change in volume of a fluid or rock per unit change in pressure applied to it.

compressibility factor

The correction applied to the ideal gas law to describe real gas behavior.

compressible

Changing volume appreciably under pressure, as gas does and liquids largely do not.

compression connector or terminal

A connector or terminal that is installed by crimping or compressing the device onto a conductor. Also called a crimp-on connector.

compression load

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

compression loading

The forces acting on a sucker rod during the downstroke because of the weight of the rods above it. Compression loading forces the rod together along its vertical axis.

compression ratio

For a compressor stage, the ratio of discharge pressure to suction pressure.

compression unit

The part of the compressor which compresses the gas. It contains the cylinder, valves and piston.

compression wave

A wave whose particle motion is along its travel direction, the fastest arrival and the one conventional seismic uses.

compression-set packer

A packer set by slacking off weight from the string, which squeezes the element out against the casing.

compressional

Relating to compression, as in the compressional wave that seismic imaging chiefly uses.

compressional velocity

Compressional velocity is the velocity of compressional waves.

compressional wave

A compressional wave (P wave) is an elastic body wave, or sound wave, in which particles oscillate in the direction the wave propagates. P-waves are the waves studied in conventional seismic data.

compressional wave (P-wave)

A compressional (P-wave) wave is an elastic body wave, or sound wave, in which particles oscillate in the direction the wave propagates. P-waves are the waves studied in conventional seismic data.

compressive strength

The stress a material withstands before crushing, specified for cement and casing.

compressive strength of formation rock

The compressive strength of a formation rock is the maximum load applied to crush the rock divided by the cross-sectional area.

compressor

A device used to move gases and increase gas pressure. In refrigeration systems, it is the component that adds energy to the refrigerant to increase its temperature and pressure and move it through the system.

compressor bearing

The bearing carrying a compressor's rotating load, and the first casualty of poor lubrication.

compressor capacity

The amount or volume of gas that a compressor moves in a given period of time.

compressor component

A part of the compressor train, each with its own inspection interval.

compressor crankshaft

The shaft converting rotation into the reciprocating motion of the pistons.

compressor cylinder

The bore a reciprocating compressor's piston works in.

compressor design

The choices of type, staging and speed that fix a compressor's duty and its limits.

compressor discharge

The outlet side of a compressor.

compressor discharge pressure

Pressure leaving the compressor, which sets both the duty and the mechanical loading.

compressor frame

The structure carrying crankshaft and cylinders and taking the reaction loads.

compressor inlet

Where gas enters a compressor, the point at which suction pressure and liquid carryover matter.

compressor loading

Opening and closing appropriate valves on the compressor, or on each stage of the compressor, until the compressor is compressing gas in all stages.

compressor oil

Lubricant in a compressor's crankcase or injected into the gas path, some of which is always carried over.

compressor operation

Running a compressor within its surge, temperature and lubrication limits.

compressor package

A compressor supplied complete with driver, cooler, scrubbers and controls on one skid.

compressor packing

The sealing rings round a piston rod, keeping process gas from the crankcase.

compressor performance

What a compressor actually delivers in flow and ratio, against what it was rated for.

compressor plant

A facility of compressors with their treatment equipment and piping, raising gas pressure for pipeline transport or processing.

compressor principle

Whether the machine raises pressure by trapping volume or by adding velocity, which decides everything else about it.

compressor shutdown

The compressor stopping, on trip or on command.

compressor suction

The low-pressure side of a compressor, where liquid carryover and low pressure do the damage.

compressor suction scrubber

Scrubber on a compressor's inlet, the last defense against liquid reaching the cylinders.

compressor system

The compressor with its drivers, coolers, scrubbers and controls treated as one unit.

compressor unloading

Opening and closing appropriate valves on the compressor so that the compressor is no longer compressing gas in any of the cylinders.

CompTIA Cloud+

The vendor-neutral certification covering cloud infrastructure operations.

CompTIA Security+ (SY0-701)

The vendor-neutral entry-level security certification, widely used as a baseline requirement.

Compton scattering

A gamma ray interaction in which the gamma ray collides with an electron, transferring part of its energy to the electron while itself being scattered at a reduced energy. It occurs with high probability at intermediate gamma ray energies (between 75 keV and 10 MeV in sedimentary formations). The total reduction due to Compton scattering depends on the electron density of the material, forming the basis for the density log.

computed dipmeter

Bed dips calculated from raw dipmeter measurements rather than read directly.

computed tomography

X-ray scanning of a core from many angles, reconstructed into cross-sectional images of its internal density.

computer platform

A computer platform is a computer or hardware device and/or associated operating system, or a virtual environment, on which software can be installed and run.

computer vision

Automated interpretation of images and video to identify features or measure them.

concentrated solution

A solution that contains a relatively large amount of solute per unit volume of solution.

concentration

The amount of one material dissolved in another material in a solution, or the amount of a contaminant in a certain volume of air.

concentric

Sharing a common center, as when casing sits centered in the wellbore and the annulus is of uniform width.

concentric fold

A fold in which each layer keeps its thickness measured perpendicular to bedding, so the layers stay concentric.

concept select

The gate where competing development concepts are narrowed to one.

conceptual design

The first engineering pass establishing feasibility and rough cost.

conceptual model

A simplified representation of how a reservoir or depositional system is put together, used to guide interpretation and modeling.

concession

A government grant giving a company the right to explore for and produce hydrocarbons within a defined area.

concession agreement

A grant of the right to explore and produce, with the state taking royalty and tax rather than a production share.

concession terms

The specific conditions attached to a concession: area, duration, work obligation and fiscal take.

condensate

In petroleum, a mixture of hydrocarbons that exist in the gaseous phase at original reservoir temperature and pressure but become liquid at surface conditions. Also, light liquid hydrocarbons with varying proportions of propane, butane, pentane and heavier fractions. In power generation, water that is condensed from steam and collected in a condenser.

condensate and feedwater system

A system of heat exchangers, pumps, pipes, and valves that directs and contains the flow of condensate from the condenser to the boiler at the proper rate to support normal boiler operation.

condensate cooler

Exchanger dropping condensate temperature before storage, cutting vapor losses from the tank.

condensate flow

The rate condensate is being produced or returned.

condensate liquids

Hydrocarbons that are gaseous in the reservoir but condense to liquid as pressure and temperature drop on the way to the separator.

condensate pump

The pump returning condensate from the condenser or receiver.

condensate ratio

The volume of liquid produced per volume of gas produced, the inverse of the gas-condensate ratio.

condensate return

Returning condensate to the boiler, recovering both its water and its heat.

condensate stabilization

Removing light ends from condensate so its vapor pressure is low enough for storage and transport.

condensate stabilization system

The stabilizer column and its heat supply, sized on the vapor pressure the product must reach.

condensate storage

The tank holding condensate before return or export.

condensate storage tank

Tank holding recovered condensate until it is trucked or pipelined away.

condensate system

The equipment collecting and returning condensate.

condensate-feedwater system

The system that removes condensate from a condenser and sends it back to a boiler as feedwater.

condensation

The phase change from a gas to a liquid at the dew point temperature; the conversion of vapor into liquid droplets.

condense

To change from a gaseous state to a liquid state.

condensed liquid

Liquid formed by condensing vapor.

condensed section

A thin interval of fine-grained sediment deposited very slowly, so it represents far more time than its thickness suggests.

condenser

A heat exchanger that removes heat from vapor (such as steam or refrigerant) and converts it into a liquid. In power plants, it condenses exhaust steam from the turbine so the resulting condensate can be pumped back to the boiler for reuse.

condenser circulation water system

The support system that supplies cooling water to a condenser.

condenser tube

The tube in a condenser through which cooling water passes.

condenser vacuum

The pressure below atmospheric in a surface condenser, which sets turbine output.

condensing drive

A miscible gasflood in which intermediate components condense out of the enriched injection gas into the oil, until the two become miscible.

conditional simulation

A geostatistical method producing multiple equally probable realizations of a property, each honouring the measured control data.

conductance

Ability of a circuit to conduct current.

conductance probes

Metal rods that are mounted at the top of a tank and extend into it to different depths. As liquid reaches a probe, a circuit is energized or de-energized, and a relay operates to initiate or terminate an action.

conduction

The primary mode of heat transfer within a solid or between solids in contact, occurring as a result of the collision of molecules or physical contact between objects.

conductive devices

Electrical equipment or components that carry electric current.

conductive invasion

Invasion in which the mud filtrate is more conductive than the formation fluid, so the flushed zone reads lower resistivity than the undisturbed zone.

conductive rock matrix model

A saturation model accounting for conduction through clay surfaces as well as through pore water, as in Waxman-Smits.

conductivity

A measure of how easily electrical current flows through a material; the inverse of resistivity.

conductivity cell

The sensor measuring a solution's electrical conductivity, and so its dissolved solids.

conductivity probes

Electrical probes that initiate an action, such as activating an alarm, in response to changes in the level of a liquid.

conductivity, electrical conductivity

The reciprocal of electrical resistivity; measures a formation's ability to conduct an electric current.

conductometric titration

A wet-chemistry method estimating cation exchange capacity by tracking a sample's conductivity as it is titrated.

conductor

A material that offers very little resistance to electron flow, allowing electric current to pass through easily. In metallic conductors such as copper or aluminum, the movable charged particles are electrons.

conductor pipe

The first and largest casing string set in a well, holding back unconsolidated near-surface material and guiding subsequent strings.

conduit body

A type of coupling that has a removable cover, allowing access to conductors for installation and maintenance.

conduits

Pathways along which fluids move through rock.

cone roof

A fixed tank roof of shallow conical form, used where vapor pressure is low.

cone roof tank

A vertical, cylindrical tank with a roof that slopes gradually to a peak, forming a vertical cone. One type of atmospheric tank.

cone-roof tank

A vertical cylindrical atmospheric tank with a roof that gradually slopes to a peak, forming a vertical cone.

confidentiality, integrity, availability

The three properties security exists to preserve, always in tension with each other.

configuration

The setting up or programming of a process control instrument to match the process conditions it will measure, including device ID, engineering units, LRV/URV, damping, calculation and output mode, and other parameters for smart devices.

configuration data

The stored settings determining how a device behaves.

configuration file

The stored file holding a device's settings.

configuration parameter

A setting fixing how an instrument or controller behaves.

confined space

A space that is large enough for a worker to enter and perform work, has limited or restricted means for entry or exit (e.g., tanks, vessels, silos, storage bins, hoppers, vaults, and pits), and is not designed for continuous employee occupancy. It may be deficient in oxygen.

confined space entry

Going inside a decommissioned storage tank to clean it out or to make repairs and inspections.

confining pressure

Confining pressure, also known as lithostatic pressure or hydrostatic pressure, is the uniform pressure exerted on a rock in the subsurface. Confining pressure has equal pressure on all sides.

conflict management

Handling disagreement so it produces a decision rather than a rupture.

conflict of interest

A personal interest that could improperly influence a procurement decision.

conflict resolution

Bringing a dispute to a settlement the parties will keep to.

conflict styles

The habitual ways individuals respond to conflict.

conflict triggers

The specific events or behaviors that reliably set off a dispute.

conformable

Describing strata deposited in unbroken succession, with no evidence of erosion or of a pause in deposition between them.

conformance

The degree to which a bid or delivered work matches what the contract specified.

conformity

A bedding surface between younger and older strata showing no evidence of erosion or non-deposition.

conical mixer

A mixer that consists of a cone-shaped housing and a screw-shaped impeller. Also called a cone and screw mixer.

conical projection

A map projection made by projecting the globe onto a cone, which is then unrolled flat.

coning

The upward or downward pull of a fluid contact toward a producing well under drawdown, bringing water or gas into the perforations.

conjugate

Of two fault or fracture sets formed together in the same stress field, at a fixed angle to each other.

conjugate faults, fractures

Faults/fractures organized into two intersecting sets with opposite shear sense are commonly referred to as conjugate faults/fractures.

conjugate pairs

Faults of the same type that are formed during the same deformation episode. These occur in two symmetrical sets with parallel strikes, opposite dips and opposite or reciprocal sense of movement to each other.

connate

Present in the rock since deposition, said of the water trapped with the sediment.

connate fluids

Liquids that were trapped in the pores of sedimentary rocks as they were deposited. These liquids are largely composed of water but also contain many mineral components as ions in solution.

connate fluids, connate water

Liquids that were trapped in the pores of sedimentary rocks as they were deposited, largely composed of water but also containing many mineral components such as ions in solution.

connate water

Connate water is the water which was trapped in the sedimentary rocks' pores during deposition.

connate water saturation

The original water left in the pore space when hydrocarbons accumulated.

connecting rod

The rod linking crankshaft to piston or crosshead.

connection

Any threaded or unthreaded joint linking two tubular components.

connection diagram

A drawing that shows the general physical locations of all major components and the connection points of all wires within a single unit.

connection gas

A short burst of gas entering the mud while a connection is made, when circulation stops and the well is momentarily underbalanced.

connector

A device used to physically and electrically join together two or more electrical conductors.

connectors

Devices used to join different parts of a personal fall arrest system together.

conradson carbon residue

The carbon left after a sample is burned off, indicating coking tendency in downstream units.

consent order

A negotiated regulatory settlement setting out required corrective actions.

consent rights

A partner's right to approve a transfer of interest to a third party.

consequentialist vs. nonconsequentialist theories

Judging acts by their outcomes against judging them by their nature or by duty.

conservator-type sealed power transformer

A power transformer that uses an expansion tank, called a conservator tank, above the transformer, to prevent air and moisture from entering the transformer enclosure.

consistency

A material's resistance to deformation and flow, arising from the cohesion between its particles.

consistometer

A laboratory instrument that stirs a cement slurry under simulated downhole pressure and temperature to measure its thickening time.

consolidated

Describing sediment compacted and cemented enough to behave as coherent, solid rock.

consolidated financial statements

Accounts combining parent and subsidiaries as though they were one entity.

consolidation

Consolidation is the process by which the volume of soil or sediment decreases, and its density increases in response to a compressive stress or increasing load.

constant

A letter, number, or symbol whose value does not change.

constant composition expansion

A PVT test in which a fluid sample of fixed composition is expanded stepwise and its volume recorded at each pressure.

constant rate

A flow rate held steady enough during a test that the analysis can treat it as unchanging.

constant velocity

An assumed single velocity, convenient for a first depth conversion and wrong in detail.

constant voltage

A supply held at a fixed voltage regardless of load.

constriction

A local narrowing that raises velocity and drops pressure, sometimes deliberate and sometimes a fault.

construction drawing

A drawing used in the construction of all or part of a building; sometimes referred to as a blueprint or a working drawing.

constructive feedback

Comment on specific behavior and its effect, given so it can be acted on.

constructivist vs. transmission model

Learners building understanding through activity against receiving it by explanation.

consumer behaviour

How people decide what to buy, which is less rational than models assume.

consuming country

A country that imports more petroleum than it produces.

contact

The interface separating fluids of different density in a reservoir — oil-water, gas-oil or gas-water.

contact angle

The contact angle is the angle, conventionally measured through the liquid, where a liquid/vapor interface meets a solid surface. It quantifies the wettability of a solid surface by a liquid.

contact stress

An ergonomic risk factor associated with contact between sensitive body tissue and a hard or sharp object. Examples of contact stress include leaning against workstation edges, pressing tool handles into the palms, or pounding with the hand. Contact stress commonly affects soft tissues and can inhibit blood flow, tendon and muscle movement, and nerve function.

contact time

The time a given fluid takes to pass a point in the annulus during pumping — how long that point is exposed to it.

contactor

In electrical systems, a large electromagnetic relay or switch inside a motor controller that directly controls the power to a motor; also called a motor starter. In gas processing, a component in an amine treatment unit where sour gas contacts lean amine and acid gases are absorbed.

contactor (absorber)

A vertical pressure vessel where gas and amine are brought together to remove acid gases from natural gas.

contactor (or absorber)

A vertical pressure vessel where gas and glycol are brought together to remove water vapor from the gas.

contactor column

The tower in which gas and a liquid such as glycol or amine are brought into contact.

contactor pressure

The pressure in the absorber, which raises how much acid gas or water the solvent takes up.

contacts

The parts of a switch, relay, or electromagnetic device that touch to form a path for current and are separated to interrupt current flow.

contaminant

Any chemical or fluid entering a mud or treatment fluid that degrades its engineered performance.

contaminant removal

Taking contaminants out of a stream to protect equipment or meet specification.

contaminants

Impurities in the air.

contaminated

The presence, or reasonably anticipated presence, of blood or other potentially infectious materials on an item or surface.

contamination gas

Gas appearing in the mud from a source other than the formation being drilled — recycled gas, additives, or a diesel or oil-base fluid.

contango

A market where forward prices exceed prompt ones, rewarding storage.

contango play

Buying prompt, selling forward and storing, when the spread more than covers the carrying cost.

content audit

A systematic review of existing content to find what works, what is stale and what is missing.

content marketing

Attracting customers by publishing material they find useful rather than by advertising at them.

content personalization

Varying what a user sees according to what is known about them.

content strategy

The plan for what content is produced, for whom and to what end.

continental crust

Thick buoyant crust that survives long enough to hold sedimentary basins.

continental margin

The transition from continental to oceanic crust, and where most sediment accumulates.

continental shelf

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

continental slope

The steeper descent from shelf edge to deep ocean, where sediment is transported basinward.

contingency plan

A prepared response to a foreseeable event that would otherwise stop normal operations.

contingent resource

Discovered quantities not currently commercial, awaiting a market, route or price.

contingent resources

Contingent Resources are the quantities of petroleum estimated to be potentially recoverable from known accumulations from a given date forward, but the associated development projects are not yet considered mature enough for commercial development due to one, or more, contingencies.

continuing education credit

The unit in which ongoing professional learning is counted toward recertification.

continuity equation

The differential form of material balance: what accumulates in a volume equals what flows in minus what flows out.

continuous emissions monitoring

A method of source sampling in which emissions of certain chemicals are measured as they occur.

continuous gas lift

Gas lift in which injection gas is supplied steadily, aerating the fluid column so the well flows continuously.

continuous level measurement

A system of level measurement that gives a numerical reading of level at all times.

continuous phase

The phase of an emulsion or suspension that forms the connected medium, with the other dispersed through it as droplets or particles.

continuous reforming

A type of catalytic reforming in which the catalyst moves through the reactors and is regenerated in a separate regeneration vessel while the reactors continue to operate.

continuous reservoir

An areally extensive reservoir holding hydrocarbon throughout, without a water contact or significant water column beneath it.

continuous sample

A sample taken using a special sampler which takes samples of the stream proportional to flow volume; the most expensive but most accurate method.

continuous sampler

Sampler taking a small portion continuously in proportion to flow.

continuous sampling

Drawing sample continuously in proportion to flow, so the composite represents the whole delivery.

continuous side-by-side correlations

Continuous side-by-side (CSB) correlations only consider displacements computed from the side-by-side buttons on the dipmeter tool pads.

continuous total dissipation

Usually specified as an absolute maximum. It is the power that can be dissipated by the op-amp package, including the load power. This parameter may be broken down by ambient temperature and package style in a table.

continuous wave telemetry

Continuous wave telemetry systems create a carrier frequency that is transmitted through the mud. They encode data using the phase shifts of the carrier.

continuous-type deposit

An accumulation that is pervasive throughout a large area and not significantly affected by hydrodynamic or buoyancy influences. Examples include basin-centered gas, shale gas, gas hydrates, natural bitumen, and oil shale accumulations.

contour

A line on a map joining points of equal value, separating higher values from lower.

contour interval

The value difference between adjacent contour lines on a map.

contour line

A contour line is a curve along which the elevation or depth has a constant value, so that the curve joins points of equal value. For example, 300 m above sea level.

contour lines

Topographic lines that show the rise and fall of Land elevation on a drawing such as a site plan.

contour map

A map showing lines of equal value, so that structure, relief and closure can be read directly.

contouring

Drawing lines of equal value across a map, the step where interpretation enters the data.

contract

To decrease in volume or size.

contract approval and award

The authority steps required before a contract can be signed and issued.

contract close-out

Settling final accounts, releasing retentions and recording lessons before the contract ends.

contract depth

The depth specified in a drilling contract at which the contractor's obligation, and payment, is completed.

contract extension

Prolonging a term beyond its original expiry, commonly the trigger for renegotiation.

contract formation

The point at which offer, acceptance and consideration combine into a binding agreement.

contract holder

The person accountable for a contract's delivery, cost and compliance once awarded.

contract matrix

The mapping of what is bought under which contract, exposing gaps and duplication.

contract specification

The quality limits a sales contract sets, which the plant is run to rather than to any technical optimum.

contract strategy

The deliberate choice of contract type, packaging and incentives before going to market.

contract/license periods

The term of a license agreement or contract may be 20-30 years with the right to negotiate an extension thereafter. It is normally divided into the initial Exploration Period, and if success is achieved, it is followed by the Exploitation Period, during which the field is developed and production takes place. A Reconnaissance Period may be allowed by Operators in advance of negotiating or bidding on one or more blocks. The Exploitation Period is usually divided into a Development Period, during which the field is planned and constructed, followed by the Production Period.

contracting

Working under a contract for services rather than as an employee.

contracting and procurement (C&P) cycle

The end-to-end process from planning a contract through sourcing, award, management and close-out.

contracts engineer

The specialist who prepares tender documents and administers the contract commercially.

contrastive language-image pretraining (CLIP)

A model trained on paired images and captions so that visual content can be matched to text descriptions.

contributing cause

A factor that made the incident more likely or worse without being sufficient on its own.

control algorithm

A set of procedures used to move a process variable closer to its setpoint.

control devices

Devices that adjust or change the operating conditions of a system.

control line

A small-diameter hydraulic line run outside the tubing to operate downhole equipment such as a surface-controlled subsurface safety valve.

control output

The action of a control device, such as a valve, motor drive, metering pump, etc. that affects a process under the direction of a loop controller.

control panel

The nerve center of a LACT unit which starts, monitors and stops the unit.

control relay

A small relay designed to control other small devices.

control unit

Instrumentation in a system of level measurement or control that, upon receiving an electrical signal, converts the signal into an indication of level or into another signal that is used to initiate or terminate an action.

control valve

A valve used to control the flow of fluid in a piping system; often operated automatically in response to the value of a process variable.

controlled circulation

A type of circulation that uses mechanical devices such as pumps to move steam and water through boiler tubes.

controlled time survey

An injection profile method that logs a radioactive tracer repeatedly over time and reads the profile from how the tracer is depleted with depth.

controlled variable

The process variable that a control loop is designed to keep at the set point; usually also the measured process variable.

controlled vs. uncontrolled pay gap

The gap remaining after adjusting for role and experience, against the raw difference.

controller

Any device that receives input information, makes decisions, and produces an output control action. Examples include PLCs, process loop controllers, servo and motor controllers, and the controller part of a variable speed drive. Also, a device that operates automatically to regulate a variable (such as rate of flow) in response to another variable (such as liquid level).

controller gain

The parameter that determines the proportional relationship between control output and error input; the inverse of proportional band. Often expressed as the change in controller output divided by the change in input.

controller output

The signal a controller sends to its final element.

ControlLogix

An Allen-Bradley family of programmable logic controllers developed specifically for networking and distributed control.

ControlNet

Allen-Bradley's proprietary network for connecting multiple remote I/O racks, processors, PLC systems, and HMIs in a plant-wide system.

convection

A heat transfer process that involves the movement of fluid (liquid or gas), where heat is transferred within the fluid as a result of currents.

convection section

The part of a furnace in which the tubes are not in a direct line of sight with the burner flames; the area of a furnace between the radiant section and the stack.

convenience store

The retail shop at a fuel station, which often earns more margin than the fuel.

conventional distillation

Distillation in which a liquid mixture's components, which have different boiling points, are separated by vaporizing part of the mixture in a distillation column at or above atmospheric pressure.

conventional gas

Natural gas, trapped by buoyancy, occurring in a porous and permeable reservoir rock, either in the gaseous phase or dissolved in crude oil.

conventional reservoir

A reservoir in which buoyancy holds hydrocarbons beneath a sealing caprock, so they can be produced by flowing to a wellbore through matrix permeability.

conventional resources

Discrete petroleum accumulations related to localized geological structural features and/or stratigraphic conditions, typically with each accumulation bounded by a down-dip contact with an aquifer, contained in rocks with relatively high matrix permeability and normally having relatively high recovery factors.

conventional seismic

Surface reflection seismic of standard design, as distinct from borehole or specialist surveys.

convergence

The movement of tectonic plates toward one another, producing compression and, where crust is consumed, subduction.

convergent

Pertaining to plates moving toward each other, generating compression and, in some cases, subduction.

convergent margin

A plate boundary where crust is being consumed, marked by trenches and volcanic arcs.

conversion

The percent of the volume of the charge feed stream in a cat cracker that is changed into other products.

conversion coking refinery

A refinery with a coker, converting the heaviest residue into lighter products.

conversion factor

The multiplier translating one energy or volume unit into another, unavoidable in a business quoted in several.

conversion funnel

The narrowing sequence from first contact to completed action.

conversion rate optimization (CRO)

Systematically improving the proportion of visitors who take the desired action.

conversion table

A data table used to find equivalents between units.

converted wave

A wave that changes mode — P to S or S to P — on reflecting or transmitting at an interface.

converter

A section of an AC inverter controller that converts the applied AC into DC.

conveyance

The method used to carry a tool string to depth — wireline, slickline, coiled tubing, tubing or drillpipe.

convolution

The mathematical operation combining two functions into a third, and the general representation of linear time-invariant filtering.

convolutional neural network (CNN)

A neural network architecture that learns local patterns in grid-structured data such as images.

convolve

To combine two functions by convolution — in seismic modeling, to filter a reflectivity series with a wavelet.

coolant level

The level in a cooling system, whose loss overheats the machine before anything else shows.

cooler

A piece of equipment in the feed preparation section that cools the feed stream before it is sent to the reaction section.

cooler louver

Adjustable vane on an air cooler controlling airflow, and therefore outlet temperature.

cooling coil

A coil carrying coolant into a vessel to remove heat.

cooling medium

The fluid carrying heat away.

cooling system

The equipment removing heat from a machine or process.

cooling tower

A structure or device in which water is broken up into drops and cooled by air flowing through it. Mechanical draft cooling towers rely on fans; natural draft cooling towers use the tendency of warm air to rise.

cooling water

Water circulated to remove process heat.

cooling water flow

The cooling water circulation rate.

cooling water system

The pumps, towers and exchangers circulating cooling water.

cooling-degree-days

The number of degrees that a given day's average temperature is above 65°F (15.5°C in European countries).

coordinate system

The reference frame positions are expressed in, and a routine source of mislocated data.

copolymer

A long-chain molecule made from two or more different types of smaller molecules.

copper carbonate

CuCO3, formerly used as a sulfide scavenger in water-base mud, reacting with hydrogen sulfide to form insoluble copper sulfide.

copper drag

A condition that leaves flakes of copper at the trailing edges of the commutator segments in a DC motor.

copper oxide

A film that forms on the surfaces of copper contacts; a poor conductor of electricity.

copper sulfate

A copper salt used in laboratory tests and as a reagent.

copper tubing

Small-bore copper tube, used for instrument air and sampling.

copyediting

Correcting grammar, consistency and style without changing the substance.

copyright

The automatic right over an original work, controlling copying and adaptation.

core

The center of an object, such as the metal structure about which transformer windings are wound. In petroleum, cylindrical samples of rock collected either from the full diameter of the borehole using a special coring drill bit, or as smaller perpendicular samples from the side of the borehole using special wireline tools.

core (rotor)

The part of a cylindrical rotor having grooved longitudinal slots in which windings are embedded; concentrates and directs the magnetic field in the rotor.

core (stator)

The part of a stator, usually made of laminated iron, that supports the stator winding and concentrates and directs the magnetic field within the stator.

core analysis

A set of techniques for measuring well conditions downhole by studying physical samples of reservoir rocks. Core analysis generally gives the most accurate insight into porosity, permeability, and other important characteristics of the well.

core barrel

A barrel positioned immediately above the core bit that retains the core after it has been cut, normally consisting of two main parts: a core-retaining inner barrel and a protective outer barrel.

core bit

The tool used to core rock.

core competencies

Competencies that typically apply across an organization at different organizational levels or in different environments. Examples could be Presentation Skills, Enterprise Resource Planning (ERP) System, Safe Working Practices, Environmental Awareness, etc.

core gamma log

A gamma ray log recorded in the laboratory by passing the core past a detector.

core image

A photographic or scanned image of a core's surface or interior, recorded as a permanent record of the rock.

core monitor

A device used to measure the amount of particulate matter in the hydrogen inside a hydrogen-cooled generator.

core plug

A small cylindrical sample drilled from a whole core for laboratory measurement.

core plug sample

Core samples that are normally drilled from full diameter cores.

core testing

Laboratory analysis of core samples to measure the rock properties a design or evaluation depends on.

core, coring

A core is a cylindrical sample of geologic formation taken during the drilling of a well. Coring is the process to acquire a core.

coreflooding

A laboratory experiment injecting fluid through a core plug to measure relative permeability, displacement efficiency or damage.

coring fluid

A drilling fluid formulated specifically for cutting core, chosen to disturb the rock's native fluids as little as possible.

coring tool

The assembly that cuts and retains a cylindrical rock sample.

corkscrew hole

A borehole drilled in a spiral rather than a straight path, from bit whirl or an unstable assembly.

corporate culture merge

Reconciling two sets of norms after a merger, a common cause of failed deals.

corporate donation

A company gift of money, goods or time to a cause.

corporate financing

How a company raises and structures the money it uses.

corporate governance

The structure of accountability between shareholders, board and management.

Corporate Social Responsibility (CSR)

A company's voluntary commitments to social and environmental benefit beyond legal duty.

corporate transformation strategy

A deliberate reshaping of what the company is and does, rather than incremental improvement.

corporation

A business incorporated as a separate legal person, limiting owner liability.

corrected gamma ray

A gamma ray curve with the uranium contribution removed, leaving the potassium and thorium response.

correcting pressure to a datum

Adjusting pressures measured at different depths to a common reference level using the fluid gradient.

correction factor

A multiplier applied to bring a raw reading to reference conditions.

corrective action

The step taken to put a fault right, as distinct from the action that contains it.

corrective action process

A formal, documented process designed to eliminate or reduce the frequency of nonconformances.

corrective vs. punitive discipline

Discipline aimed at changing behavior against discipline aimed at penalizing it.

correlate

To match features between wells or sections so that equivalent depths and units can be identified.

correlation

The establishment of equivalence between units in different wells or sections, on the basis of age or of similar character.

correlation coefficient

A correlation coefficient is a measure of agreement between two curves.

correlation information

Correlation information is used to determine the attitude of bedding planes with respect to the dipmeter tool.

correlation interval

The depth window over which two logs or traces are compared.

correlation log

A log run principally so that depths and units can be matched against offset wells.

correlation vs. causation

Two variables moving together against one producing the other.

correlative

Able to be matched between wells, as a surface traced across a field.

correlative conformity

The surface in the basin that corresponds in time to an unconformity nearer shore.

correlative surface

A surface traceable between wells, used to build the stratigraphic framework.

correlogram

A correlogram is an image of correlation statistics.

corrode

To be attacked chemically, principally by acid gas and oxygenated water.

corrosion

An electrochemical reaction that deteriorates and weakens metal surfaces, which can eat away the metal of equipment such as above ground storage tanks.

corrosion control

The measures taken to prevent or slow corrosion — coatings, inhibitors, cathodic protection and material selection.

corrosion coupon

A weighed metal specimen exposed in the flow stream, whose weight loss after a set period gives the corrosion rate.

corrosion fatigue

Cracking of metal under cyclic stress in a corrosive environment, at stress levels it would survive in dry air.

corrosion inhibitor

A chemical added to acid or produced fluid that slows attack on the steel it contacts.

corrosion product

The solid a corrosion reaction leaves behind, whose composition identifies the mechanism attacking the metal.

corrosion rate

The rate at which metal is lost to corrosion, expressed as thousandths of an inch of penetration per year from coupon weight loss.

corrosion-resistant alloy (CRA)

An alloy specified for completion components where carbon steel would not survive the produced environment.

corrosive

Any material that eats away another material by electrical or chemical action.

corrosive material

A substance that attacks metal or tissue on contact.

corrosives

Chemicals that cause visible destruction of or irreversible alteration in living tissue by chemical action.

COSMOS (gas value chain simulation)

The gas value chain simulation, developing offshore gas in the fictional Republic of Cosmos.

cosolvent

A secondary solvent added in small amount to make the primary solvent work better.

cost and schedule contingency

The allowance held for identified risks, distinct from padding an estimate.

cost estimation and budget evolution

How an estimate is refined from concept to award, and how the budget tracks that refinement.

cost of supply

What it costs to bring a barrel to market, the basis for ranking sources on a supply curve.

cost oil

The percentage of production (e.g. 40%) that a PSC Contractor receives to repay its capital, operating and, if permitted, interest costs. In some cases, the Operator is allowed to recover an uplift (e.g.120%) of costs with the additional amount referred to as an Investment Credit. The Cost Oil quantity is converted to dollars using one or more reference crude market prices.

cost per hire

The total recruitment cost divided by hires made.

cost recovery

The mechanism by which a contractor is repaid its capital and operating spend out of production.

cost recovery ceiling

The cap on how much production may be taken as cost oil in any period.

cost-benefit analysis

Comparing the total expected benefits of a course of action against its total costs.

cost-volume-profit (CVP) analysis

Modeling how profit responds to changes in price, cost and volume together.

costs incurred

Capitalized and expensed spending in the period, disclosed by category in oil and gas reporting.

cosurfactant

A second surface-active chemical, usually a short-chain alcohol, added to make the primary surfactant more effective.

coulomb

The amount of excess charge on the positive side of a capacitance of one farad charged to a potential difference of one volt.

Coulomb force

The Coulomb force, also called the electrostatic force or Coulomb interaction, is the attraction or repulsion of particles or objects because of their electric charge.

Coulomb forces

The attraction or repulsion of particles or objects because of their electric charge; also called the electrostatic force or Coulomb interaction.

counselling

Addressing a personal difficulty affecting work, distinct from coaching for performance.

counterbalance

Any force equally counteracting another. On a beam pumping unit it is the weight used to balance the weight of the sucker rod string.

counterbalance valve

A pressure control valve that is used to support a hoisted load or prevent a load from dropping.

counterbalance weight

Weight added to a pumping unit's beam or cranks to offset the rod string load, so the prime mover works evenly through the cycle.

counterbalance winch

The winch on a snubbing unit used to lift tubulars and tool strings into the work basket.

counterclockwise

Turning in the direction opposite to a clock's hands.

counterflow

A fluid flow pattern in a heat exchanger such that two fluids flow past each other in opposite direction. Also called reverse flow.

counterion

Counterions are the mobile ions found in ion exchange polymers and colloids. A counterion can be either an anion or a cation, depending on whether it carries a negative or positive charge, respectively. Consequently, a counterion to an anion will be a cation and a counterion to a cation will be an anion.

counterion, counter-ion

A counterion is the ion that accompanies an ionic species in order to maintain electric neutrality.

counterpart

The person on the other side of the table.

counterparty

The other party to a contract, whose credit and performance must be assessed.

counterparty credit risk

The risk that the other side cannot pay when settlement falls due.

counterweight

A weight that is built into the body of a forklift that is used to offset the load's weight and help prevent the forklift from tipping over.

country risk

The exposure that comes from where a project sits: politics, currency, expropriation, security.

country risk assessment

Evaluating the political, economic and legal exposure of operating in a given country.

coupled physico-chemical system

A Physico-chemical system is a system involving parameters such as the water temperature, pH, dissolved oxygen, conductivity, salinity, nitrate, sulfate, chloride, total hardness, calcium and magnesium elements.

couplets

Paired laminations recording a cyclic depositional process.

coupling

In electronics, the method of connecting two circuits together—directly coupled via wire, or indirectly (AC) coupled through a capacitor or transformer. In conduit work, a fitting used to join two lengths of the same type of conduit together.

coupling capacitor voltage transformer (CCVT)

A device used to put a transfer trip signal onto a line or remove a transfer trip signal from a line.

coupling hub

The half of a coupling fixed to each shaft.

coupon

A small specimen of the material of interest, exposed to a process fluid so corrosion can be measured from its weight loss.

coupons

Small, specially designed metallic or non-metallic test specimens or samples that are placed on the external surface of a pipeline to assess the rate and severity of corrosion.

covalent bond

A bond formed by shared electrons, which holds hydrocarbons together.

covariance

A measure of how two variables move together, underlying geostatistical estimation.

covenant

A promise in a loan agreement whose breach lets lenders act before default occurs.

coventurer

A coventurer is an organization which takes an equity share in an oilfield property and the various associated activities.

cover letter

The accompanying letter making the case for this candidate for this role.

cover ratio

Any measure of how far cash flow exceeds the obligation it must fund.

CPMG

The Carr-Purcell-Meiboom-Gill pulse sequence, which refocuses dephasing protons into a train of spin echoes.

CPR

Cardiopulmonary resuscitation - A method of restoring a shock victim's breathing and heartbeat to normal.

CPVC

Chlorinated polyvinyl chloride, a type of rigid plastic piping that withstands greater pressure/temperature than PVC; used for hot and cold water distribution and for chemical process piping.

crack spread

The traded difference between crude and refined product prices, standing in for refining margin.

cracked gas

The hydrocarbon vapors produced by a cat cracking unit.

cracked gas plant

A unit that recovers light end products from unstabilized cat-cracked gasoline.

cracked hydrocarbon

A hydrocarbon produced by breaking a larger molecule, and therefore unsaturated and reactive.

cracking

A process in which large hydrocarbon molecules are decomposed into smaller molecules, creating undesired light ends and coke.

cracking pressure

The pressure at which a spring-biased valve begins to open and allow fluid to flow through.

cracking refinery

A refinery with catalytic cracking, able to convert gas oil into gasoline.

cracking unit

The refinery unit breaking heavy molecules into lighter ones.

crane

Any of several types of mobile or stationary machines used for lifting and moving loads from one place to another.

crank end

The compressor cylinder end nearest the crankshaft, where the piston rod passes through packing.

crankcase

The enclosed housing holding a machine's crankshaft and its oil.

crankcase oil

The lubricating oil in the crankcase, whose analysis reveals wear before it is audible.

crankshaft

The shaft converting rotation to reciprocating motion.

craton

A stable region of continental crust that has escaped significant tectonic or orogenic deformation for a long period.

cratonic

Of the ancient stable interior of a continent, tectonically quiet and thinly covered.

creaming

The separation of an emulsion into a concentrated layer of droplets and a clearer layer, without the droplets coalescing.

created fracture

The fracture actually produced by treatment, as distinct from the one designed.

credibility and persuasion

Earning the standing that makes an argument land, before making it.

credit

Borrowed money, and the record of how reliably it has been repaid.

crest

The highest point of a structure, a wave or a reef.

crestal gas

Gas accumulated at the top of a structure, above the oil column.

crestal gas injection

Injecting gas into the top of a structure to maintain pressure and displace oil downward.

cresting

The lateral equivalent of coning in a horizontal well, where the fluid contact rises or falls along the length of the lateral under drawdown.

Creutzfeld-Jacob disease

A rare, fatal brain disorder which causes a rapid, progressive dementia and associated neuromuscular disturbances or jerks. Although CJD can be genetic in origin, it's also transmittable through contact with infected tissue.

crevasse

A break in a levee through which a channel spills sediment onto the floodplain.

crevasse subdeltas

Crevasse subdeltas develop on modern river-dominated delta plains and consist of relatively large receiving bays that have depths of 32-49 ft (10-15 m). These may be affected by the interaction of river currents and marine processes. The process by which these are formed is referred to as “bay filling”. Crevasses form as a result of the movement and shear stress that is generated when two semi-rigid pieces above a plastic substrate have different rates of movement.

CRG

Common receiver gather — the set of traces recorded at one receiver from many shots.

crimp

A mechanical compression joint on a wire or tube.

crimper

A tool used to apply compression to attach a terminal or connector to a conductor.

crisis response

The organized reaction to a serious incident, planned before it is needed.

critical angle

The angle of incidence at which the refracted ray travels along the interface, beyond which all energy is reflected.

critical asset

An asset whose failure or compromise would materially disrupt operations or safety.

critical damping

The least damping that stops a system oscillating, returning it to rest in the shortest time without overshoot.

critical flow prover

A device measuring gas rate by flowing it through a choke at critical velocity.

critical flow rate

In sand control, the highest production rate at which solids production stays uniform rather than escalating.

critical gas flow rate

The rate at which gas velocity through a restriction reaches the speed of sound, so downstream pressure no longer affects the rate.

critical matrix

The near-wellbore rock in which damage controls productivity and which a matrix treatment is designed to restore.

critical moment

The point in a petroleum system's history that best represents the generation, migration and accumulation of its hydrocarbons.

critical path

The chain of activities whose delay directly delays the whole project.

critical path analysis

Finding the longest chain of dependent tasks, which determines the project duration.

critical point

The point at which the density of water and the density of steam are the same; 705 degrees Fahrenheit and 3206 psi.

critical rate

The highest production rate at which a fluid contact stays stable, so water or gas is not coned into the well.

critical reflection

The reflection occurring when the incidence angle equals the critical angle, so the refracted ray grazes the interface.

critical thinking

Evaluating claims and evidence deliberately rather than accepting them as presented.

critical water saturation

Critical water saturation is defined as the water saturation at which the corresponding water phase relative permeability falls below a threshold value.

criticality analysis

Ranking assets by what their loss would mean, to prioritize protection.

crooked hole

An older term for a wellbore that has deviated unintentionally while drilling.

crop out

Of a rock body, to be exposed at the Earth's surface.

cross dipole

A sonic tool with two orthogonal dipole transmitters and matching receivers, recording shear waves in two perpendicular planes.

cross over

A short sub connecting two components whose threads differ in type or size.

cross-bedding

Layering within a stratum that is at an angle to the main bedding plane, where the original depositional layering is tilted but not as a result of post-depositional deformation. Sometimes termed cross-stratification.

cross-bedding, cross-beds

Cross-bedding is horizontal units that are internally composed of inclined layers. The original depositional layering is tilted, and the tilting is not a result of post-depositional deformation.

cross-connection box

Patch panels that use patch cords to reverse the transmit-receive polarity. That is, data coming into the panel from one device on that device's transmit fiber crosses over to go out to another device on its receive fiber.

cross-cultural body language

Nonverbal signals whose meaning changes between cultures, a common source of misreading.

cross-cultural competency

The ability to work effectively with people whose norms and expectations differ.

cross-cultural negotiation

Negotiating where the parties' norms about directness, time and relationship differ.

cross-flow

In reservoir engineering, a condition where two production zones with dissimilar pressure characteristics communicate during production, with fluid from the high-pressure zone flowing preferentially to the low-pressure zone. In heat exchangers, a fluid flow pattern in which two fluids flow past each other at right angles.

cross-functional team

A group of employees from a similar hierarchical level, but from different work areas/groups/functions, who come together to accomplish a task.

cross-section

The effective area within which a neutron must pass to interact with an atomic nucleus.

cross-sectional

Pertaining to a vertical slice through a volume, as opposed to a plan or map view of it.

cross-sectional area

The area flow passes through, which with rate gives velocity.

cross-stratification

Inclined layering within a bed, recording migrating ripples or dunes and the current that made them.

cross-tightening

A pattern for tightening flange bolts to ensure even compression on a gasket.

crosscorrelate

To compare two different waveforms as a function of time shift, measuring how similar they are at each lag.

crosscorrelation

The comparison of two different waveforms as a function of time shift, quantifying their similarity at each lag.

crosscorrelation flowmeter

A flowmeter that times how long a natural disturbance in the stream takes to travel between two sensors a known distance apart.

crosshead

Device which converts rotary motion into reciprocating motion.

crosshead guide

The surface constraining a crosshead to straight-line travel between crank and piston rod.

crossline

A line in a 3D seismic volume perpendicular to the direction the data were acquired in.

crosslinked

Chemically bonded into a gel structure, which raises a fracturing fluid's carrying capacity.

crosslinker

A compound, usually a metal salt, added to a base gel to bond polymer chains into a three-dimensional network and raise viscosity sharply.

crosslinking

Chemically bonding polymer chains to build a fracturing gel's carrying capacity.

crossover analysis

Finding the point at which one alternative becomes better than another.

crossover service tool

The gravel pack tool that routes slurry from inside the workstring out into the screen-casing annulus and returns carrier fluid up the washpipe.

crossplot

A plot of one variable against another, used to identify populations and relationships that a single log curve cannot show.

crossplot porosity

Porosity read from the position of a point on a two-log crossplot, normally density against neutron.

crosstalk

A condition where the signal on one twisted pair of conductors is picked up on another pair in the same cable. Also, the ratio of the change in output voltage of a driven channel to the resulting change in output voltage from an undriven channel.

crosswell

Measurements made between two wells, giving resolution between them that surface seismic cannot.

crosswell electromagnetic tomography

Imaging resistivity between two wells from electromagnetic signals transmitted in one and recorded in the other.

crosswell reflection tomography

A crosswell inversion that uses reflection traveltimes as well as direct arrivals, imaging beyond the plane between the two wells.

crosswell seismic

Seismic recorded between two boreholes, giving high resolution in the interwell space.

crosswell seismic tomography

A survey that sends seismic energy between two wells, source in one and receivers in the other, then inverts the arrivals for the velocity structure lying between them.

crosswell tomography

The inversion of signals broadcast from a source in one well to receivers in another, producing an image of the rock between them.

crown block

The fixed set of pulleys, or sheaves, located at the top of the derrick, over which the drilling line (a large-diameter wire rope) is threaded.

crown valve

The topmost valve on a Christmas tree, giving vertical access into the wellbore.

CRT

Cathode ray tube; an electron beam tube in which the beam can be focused on a luminescent screen and varied in both position and intensity to produce a visible pattern.

crude carrier

A tanker built to carry crude oil.

crude distillation

Separating crude into fractions by boiling range.

crude distillation unit

A unit in a refinery in which distillation is used to physically separate crude into different groups of hydrocarbons.

crude grade

A named crude with defined quality, traded against its own differential.

crude handling agreement

The contract governing how a partner's crude is received, stored and lifted at a terminal.

crude market

The market in which crude oil is traded.

crude oil

Petroleum that exists in the liquid phase in natural underground reservoirs and remains liquid at atmospheric temperature and pressure.

crude oil (crude)

The liquid form of petroleum.

crude oil assay

The laboratory workup of a crude showing what products and yields a refinery can expect from it.

crude oil demand

Consumption of crude, driven ultimately by demand for refined products.

crude oil distillation unit (crude unit)

The unit in a refinery where incoming crude is physically separated into groups of hydrocarbons.

crude oil future

A standardized exchange contract for future delivery of crude.

crude oil grade

A named crude with a defined quality, traded against its own differential.

crude oil market

The physical and paper markets in which crude is traded.

crude oil pipeline

A pipeline carrying crude from production or terminal to refinery.

crude oil production

The volume of crude lifted over a period.

crude oil reserve

The quantity of crude estimated recoverable under current conditions.

crude oil sales contract

The agreement fixing quantity, quality, pricing formula and delivery terms for a crude sale.

crude oil storage

Tankage holding crude between production, transport and refining.

crude oil tanker

The vessel carrying crude oil in bulk between loading and discharge ports.

crude oil transportation

Moving crude by pipeline, tanker, rail or truck.

crude production

The volume of crude oil produced over a period.

crude quality

The density, sulfur and contaminant profile that determines what a crude is worth.

crude reserve

The quantity of crude estimated to be recoverable.

crude tanker

A vessel carrying crude oil in bulk.

crude theft

Illegal tapping of pipelines or diversion of cargo, a major loss in some producing regions.

crude unit

The refinery unit distilling crude into its main fractions.

crushed zone

The thin shell of pulverized, low-permeability rock left around a perforation tunnel by the shaped-charge jet.

crust

The Earth's thin outermost compositional shell, roughly 5 km thick under oceans and up to 75 km beneath continents.

crustal

Relating to the earth's crust and its large-scale structure.

crustal magnetic field

The part of the measured magnetic field arising from magnetic minerals in the crust, both induced and remanent.

cryogenic

A term relating to very low temperatures (less than -50°F / -73°C to -150°F / -100°C). Used in the processing of natural gas to remove natural gas liquids.

cryogenic expander

The turbine chilling gas by expansion to recover natural gas liquids.

cryogenic processing

Processing at very low temperature to recover ethane and heavier components gas would otherwise carry away.

cryogenic tank

A tank that has been modified to contain liquids at temperatures below -100 degrees Fahrenheit.

cryogenic temperature

Temperature low enough to liquefy light gases, below about minus 100 Celsius.

cryptocrystalline

Cryptocrystalline is a rock texture in which the individual crystals are too small to be seen with the naked eye or even with a standard optical microscope. The crystals are so tiny that they can only be identified using advanced techniques like X-ray diffraction.

cryptography

The mathematics of protecting information so only intended parties can read it.

crystallization

The removal of a solid from a solution by increasing the solution's concentration above its saturation point so that crystals form.

crystallization temperature

The temperature at which salt begins to crystallize out of a brine of given density as it cools.

CSR project strategy

Choosing social investments that address real needs rather than producing visible gestures.

CSS

Cyclic steam stimulation: injecting steam into a well, letting it soak, then producing from that same well, and repeating the cycle.

CT

Coiled tubing — a continuous length of small-diameter pipe carried on a reel and run into a live well.

cubic packing

An arrangement of uniform spheres stacked directly above one another, giving the loosest regular packing and about 47.6% porosity.

cultural anomaly

A geophysical anomaly caused by man-made objects — pipelines, fences, rails, buildings — rather than by geology.

cultural awareness

Recognizing that one's own norms are not universal.

cultural competence

The ability to work effectively across cultural differences.

cultural intelligence

The learnable capability to adapt behavior appropriately in unfamiliar cultural settings.

cultural noise

Unwanted signal generated by human activity — traffic, power lines, machinery — that interferes with a geophysical measurement.

culturally diverse teams

Teams whose members bring different cultural expectations about work and communication.

culture

Culture refers to any physical items specific to the prospect area that are important to know when planning the exploration program, for processing and interpreting the data. This could include pipelines, roads, lease areas, known shorelines, faults, etcetera.

culture redesign

A deliberate effort to change shared norms, which requires changing what is rewarded.

cumene

An aromatic intermediate used to make phenol and acetone.

cumulative data

Information concerning the time-integrated total of some variables. For example, how much water or electricity has been used from some baseline time to the present.

cumulative production

The total volume of oil or gas a well or field has produced up to a given date.

curing

The controlled hardening of cement, resin or elastomer under defined temperature and pressure until it develops its designed properties.

current

The movement or flow of electrons (free electrons through a conductor), measured in amperes. The unit commonly used to specify current is the ampere, and in electrical formulas, current is typically represented by a capital I.

current (electric)

A flow of electrons in an electrical conductor. The strength or rate of movement of the electricity is measured in amperes.

current coil

The relay coil energized by circuit current rather than by voltage.

current limiting fuse

A fuse that limits the amount of time that current is allowed to pass through it.

current state vs. future state

How things work now against how they are intended to work.

current transformer

A transformer that reduces higher line current to a proportional lower current and supplies the lower current to protective relays or to instruments that monitor or measure the line current.

curriculum learning

Provides the ability to create and deliver a curriculum of learning to CMS Online users. It also allows users to register for or launch courses through the CMS Online interface.

• Delivers a predefined learning curriculum to the end user
• Displays the curriculum in sequential learning blocks
• Allows the end user to open each block independently to see the list of courses and activities
• Allows the end user to view their training status and launch training within one view.

cursor

An on-screen marker on an oscilloscope that can be aligned with a waveform to enable a user to take accurate measurements.

curtailment

Reducing deliveries or output below what was contracted or available.

curve

A single log measurement presented against depth on a display.

curve fitting

Fitting a theoretical function to measured data, usually by minimizing the misfit between them.

curve matching

Comparing measured data against a family of type curves whose behavior is understood, to identify which model the data follow.

cushion

A column of fluid — usually water or nitrogen — left in the drillstem so the formation sees a chosen backpressure when the test tool opens.

cushion gas

The gas that must remain in a storage reservoir to maintain pressure, and cannot be sold.

custody transfer

An event when products are received from or delivered to another party.

custom data monitor

A software troubleshooting tool that allows you to build a table that displays specific PLC data in real time.

custom data monitors

A software troubleshooting tool that allows you to build a table that displays specific PLC data in real time.

customer experience

The whole of what a customer encounters across every interaction, not just the transaction.

customer journey

The whole path a customer takes across touchpoints, mapped from their perspective.

customer loyalty

Continued custom despite available alternatives.

customer relationship management (CRM)

The systems and practices for managing interactions with customers over time.

customer service expectations

What the customer believes they were promised, against which the service is judged.

customer types

The recurring customer patterns a service person meets, each responding to a different approach.

customer value

What the customer gets relative to what they give up to get it.

CUSUM

A process control system that keeps a running total of the difference between the average value of a variable and its aim, or desired value.

cut

The fraction of total produced flow made up by one fluid — water cut being the common case.

cut and thread fishing technique

A wireline recovery method in which the stuck wire is cut at surface and the free end threaded through pipe run over it.

cut and thread, cut and thread fishing technique

Cut and thread is a fishing technique for recovering wireline stuck in a wellbore. In cut and thread operations, the wireline is gripped securely with a special tool and cut at the surface. The cut end is threaded through a stand of drill pipe. While the pipe hangs in the wellbore, the wireline is threaded through another stand of drill pipe, which is screwed onto the stand in the wellbore. The process is repeated until the stuck wireline is recovered.

cut bank

A cut bank, also known as a river cliff or river-cut cliff, is the outside bank of a curve in a water channel that is continually undergoing erosion. Cut banks are found in abundance along mature or meandering streams.

cut oil

Crude oil carrying water, usually as an emulsion, so that it fails sales specification until treated.

cut point

In solids control, the particle size an item of equipment has a stated probability of removing.

cut points

The temperatures at which fractions separate.

cutaneous hazards

Chemicals that affect the skin.

cutaway

A drawing with part of the outer body removed to show what is inside.

cutback asphalt

A type of liquid asphalt produced by mixing straight-run asphalt with lighter distillates or oily distillates.

cutoff

A state in which an amplifier is not conducting at all.

cutout switch

A switch removing a device from service.

cuts

See Fractions.

Cutt point

The equivalent spherical particle diameter a screen retains, derived from image analysis of its actual openings.

cutter bit

The cutting element or the bit carrying it.

cutting

A welding application that burns metal surfaces apart.

cuttings

Small pieces of rock that break away due to the action of the drill bit's teeth, which are screened out of the liquid mud system at the shale shakers.

cuttings lifting

The carrying of drilled rock out of the annulus by the circulating fluid.

cuttings, drill cuttings

Cuttings are small pieces of rock that break away due to the action of the drill bit's teeth, which are screened out of the liquid mud system at the shale shakers.

cuttings, drill cuttings, ditch cuttings

Small pieces of rock that break away due to the action of the drill bit's teeth, screened out of the liquid mud system at the shale shakers. Sometimes termed drill cuttings or ditch cuttings.

CWA

The Clean Water Act, the US statute controlling discharge of pollutants into navigable waters.

cybersecurity

The technologies and processes protecting internet-connected control and information systems from attack.

cybersecurity resilience

The ability to keep operating, and recover, when an attack succeeds rather than only preventing one.

cycle

In alternating current, one complete change in voltage from zero to maximum positive, back to zero, to maximum negative, and back to zero. In quality control, a pattern of instability on a control chart formed when data points alternate above and below the process centerline.

cycle gas

Gas that is compressed and injected back into the reservoir after its liquids have been removed.

cycle skip

A sonic log error in which the receiver triggers a cycle late on a weak arrival, producing an abrupt spike to a longer transit time.

cycle skipping

An error in sonic logging that occurs when both detectors are not activated by the same peak or trough of the returning wave train, causing one to be activated by the next cycle instead. It is easily identified because the time difference equals the time interval between successive pulse cycles.

cycle time

The time for mud to travel the complete circuit, from the suction pit down the string and back to surface.

cyclic reforming

A type of catalytic reforming in which a "swing reactor" regenerates a portion of the catalyst while the other reactors continue to operate.

cyclic steam injection

A thermal method in which steam is injected into a well, allowed to soak, and the same well is then produced — repeated as cycles.

cycling plant

A surface facility that strips liquids from produced gas and reinjects the dry gas to keep a condensate reservoir above its dewpoint.

cyclization

A reforming reaction in which a paraffin is converted to a naphthene.

cyclohexane

A six-carbon saturated ring, an intermediate in nylon manufacture.

cyclone

A cone-shaped vessel that uses centrifugal force to separate solid particles (such as catalyst) from air, gas, or other gases. Also called a cyclone separator.

cyclone separator

A cone-shaped vessel that uses centrifugal force to remove contaminants from a gas or vapor stream.

cyclonic passage

A device which creates a swirling flow of the fluids.

cycloparaffin

See Naphthene.

cyclothem

A repeating succession of strata deposited through one full cycle of depositional conditions, typically marine to non-marine and back.

cylinder

A comparatively small, heavy, bottle-shaped vessel used to store compressed gases.

cylinder block

The casting carrying an engine's or compressor's cylinders.

cylinder clearance

The space that exists in the head end or crank end of the cylinder. Increasing or decreasing this space adjusts the volume of gas the cylinder can handle.

cylinder head

The cover closing the end of a cylinder.

cylinder operator

A valve actuator in which hydraulic or pneumatic pressure on a piston drives the stem directly.

cylinder pressure

Pressure inside a working cylinder, which with volume gives the work done.

cylinder valve

The valve admitting or releasing gas in a reciprocating cylinder.

cylinder volume

The swept volume of a cylinder, which with speed gives displacement.

cylinder wall

The bore surface a piston runs against, and where scoring shows lubrication has failed.

cylindrical rotor

A type of rotor commonly used with AC generators when high speeds of rotation and large amounts of power are needed; its cylindrical construction allows it to be affected less than a salient-pole rotor by centrifugal force and other stresses involved at high speeds.