Kimray Oilfield Glossary

The Kimray Oilfield Glossary is a reference that provides definitions for common terms used in the oil and gas industry. The content of this oilfield glossary is provided by Kimray’s team of experienced product managers and application technicians. 

Abatement – The act or process of reducing the intensity of pollution

Absorption – The process in which a fluid is dissolved by a liquid or a solid (absorbent)

 ReAdjusting Screw – Screw or bolt used to make small, precise adjustments for set points or tension

Adsorption – The process in which atoms, ions, or molecules from a substance (gas, liquid, or dissolved solid) adhere to a surface of the adsorbent; adsorption is a surface-based process where a film of adsorbate is created on the surface while absorption involves the entire volume of the absorbing substance

Accumulator – Dehy storage tank, surge tank

Acreage – Land leased for oil and gas exploration

Air Motor – An air motor opens or closes shutters attached to a compressor’s heat exchanger; pneumatically operated by a thermostat

Anticline – An arch of stratified rock in which the layers bend downward in opposite directions from the crest; may form a trap for hydrocarbons

Aquifer – An underground stratum of water-bearing permeable rock, sand, or gravel from which groundwater can be extracted using a water well

Artificial Lift – Any method used to raise oil to the surface after a well ceases to flow

Baffle – Component within a separation vessel designed to momentarily slow the flow of fluids, aiding in the oil/water separation process

Ball and Cone Seat – Trim design used in control valves; can be one of three styles: snap (quick opening, carbide), nominal (standard), equal percentage (ep)

Barrel of Oil Equivalent (BOE) – A measure used to aggregate oil and gas resources or production; one BOE is approximately equal to 6,000 standard cubic feet of natural gas

Basin – A broad area of the earth beneath which the strata dip usually from the sides toward the center and allows an accumulation of sediments generally brought by water

BCF – One billion cubic feet of natural gas

Bitumen – A highly viscous form of crude oil (greater than 10,000 centipoise) that must be heated or combined with lighter hydrocarbons to be produced; in natural form, contains sulfur, metals, and other nonhydrocarbons

BOED – Barrels of oil equivalent per day


  • n: the inside diameter of a pipe or a drilled hole
  • v: to penetrate or pierce with a rotary tool

British Thermal Unit (BTU) – The amount of energy (heat) needed to raise the temperature of one pound of water by one degree Fahrenheit

Burner Valve

  • On a dehy unit or line heater, the burner valve controls the flow of gas to the fire tube to maintain a constant temperature in the process bath
  • On a heater treater, the burner valve controls the flow of gas to the fire tube to maintain a constant temperature in the vessel

Cage Guided – A type of trim set; typically a piston travels up and down, and travel is directed by a cage assembly

CAPEX – Capital expenditures

Cavitation – Cavitation is the formation of vapor cavities in a liquid – i.e., small liquid-free zones (“bubbles” or “voids”) – that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities where the pressure is relatively low. When subjected to higher pressure, the voids implode and can generate an intense shockwave. Cavitation is a significant cause of wear in some engineering contexts. Collapsing voids that implode near to a metal surface cause cyclic stress through repeated implosion. This results in surface fatigue of the metal causing a type of wear also called “cavitation.” Cavitation can occur in control valves. If the actual pressure drop across the valve as defined by the upstream and downstream pressures in the system is greater than the sizing calculations allow, pressure drop flashing or cavitation may occur.

Coal Bed Methane (CBM) – Natural gas extracted from coal beds

Coalesce – To gather together; to unite into a whole

Condensation – Change of the physical state of matter from gaseous phase into liquid phase

Contactor (Glycol Absorber) – In a glycol dehydrator unit, the cylinder composed of various perforated trays in which wet gas and glycol are put in contact

Conventional Resources – Hydrocarbon accumulation present in rocks with semi- to high permeability and which generally have relatively high recovery factors

Critical Flow (Choked Flow) – Point at which no additional flow is possible through an opening

CTB  Central Tank Battery

Dehydration – To remove water from a substance; dehydration is used to prevent corrosion and free-water accumulation in the low points of a pipeline

Dehydration Unit – Set of vessels used to remove water from natural gas

Desiccant – A hygroscopic substance that induces or sustains a state of dryness (desiccation) in its local vicinity in a moderately well-sealed container

Developed Acreage – The acres allocated or available to productive or potentially-productive wells

Development Well – A well drilled within a proven zone of an oil or gas reservoir to the depth of proven productivity

Diaphragm – Any membrane or partition that separates one thing from another

Downstream – The downstream industry includes oil refineries, petrochemical plants, petroleum products distributors, retail outlets and natural gas distribution companies; the downstream industry touches every province and territory wherever consumers are located an provides thousands of products such as gasoline, diesel, jet fuel, plastics, and natural gas

Drip Pot – Vessel that allows liquids to accumulate at its location

DUCs – Drilled Uncompleted Wells

E&P – Exploration and production

Economically Producible – A resource that generates returns exceeding or likely to exceed the costs of operation

Elastomer – Materials made of polymers that are joined by chemical bonds, e.g., diaphragms and o-rings  

Emulsion – A suspension of small globules of one liquid in a second liquid with which the first will not mix

Energy Exchange Glycol Pump – The Energy Exchange Glycol Pump utilizes the energy of wet glycol at absorber pressure as a source of power to circulate the glycol in a gas dehydrator. The pump transfers the energy available from the wet glycol, at absorber pressure, to an “equivalent” volume of dry glycol at reboiler pressure. In order to circulate the glycol, additional energy is needed to overcome friction losses within the pump and connecting piping. This additional energy is supplied by gas at absorber pressure.

Environmental Assessment – Research to determine the potential direct, indirect, and total environmental impacts of a project

Equal Percentage Trim – Trim type; equal increments of travel produce equal percentage changes in the existing control valve

Estimated Ultimate Recovery (EUR) – Reserves remaining on a given date and cumulative production up to that date

Fill Hatch – A covered opening in the shell of a production unit through which fluid can be added to the water bath. 

Float – The element of the level control assembly designed to rise and fall with the level of the fluids inside the vessel. 

Fluid Inlet – A piping arrangement that directs fluids into a separator. 

Free Water Knockout (FWKO) – A vertical or horizontal separator used mainly to remove any free water that can cause problems such as corrosion and formation of hydrates or tight emulsions, which are difficult to break; liquids that are discharged from the free-water knockout are further treated in vessels called treaters

Gas Outlet – A piping arrangement that directs gas out of the vessel 

Gas Pilot Operated Pressure Regulator

  • The Gas Operated Pressure Regulator combines a pressure pilot with a control valve; except where liquid or very low gas pressure is involved, upstream gas is used to operate the valve
    • Back Pressure Regulator: Maintains a constant upstream pressure. It limits upstream pressure by adjusting open to relieve excess pressure or conserves upstream pressure by adjusting closed to limit the flow to downstream.
    • Pressure Reducing Regulator: Maintains a constant downstream pressure. It limits downstream pressure by adjusting closed to limit the flow to downstream or supports downstream pressure by adjusting open to allow additional flow from upstream. On a compressor, the pressure reducing regulator is used as a suction controller to maintain a constant pressure into the compressor. The Pressure Reducing Regulator is also used as a low suction or make-up gas regulator.
    • Differential Pressure Regulator: Maintains a constant difference between upstream and downstream pressure.

Gas Well – A well that primarily produces gas; legal definitions vary from state to state

Gen II – The Gen II Liquid Level Controller is used to pneumatically control the liquid level within a vessel 

Heavy Oil – Crude oil with an API gravity less than 20°; high viscosity prevents easy flow 

High Pressure Control Valve – The Kimray High Pressure Control Valve is designed for controlling a variety of fluids at pressures up to 6000 psig (413 bar) and can be used for the discharge of liquid or gas from vessels, separators, treaters, knockouts, similar liquid accumulators, and other areas of natural gas production; comes with a variety of connection types from 2 inches to 10 inches

High Pressure Pressure Reducing Package – Combination high pressure control valve and proper pilot used to control downstream pressure

High Temperature Shut-down – On a line heater or dehy unit, the T-12M is a safety switch that monitors the water bath’s temperature and has the ability to shut down the burner if the temperature climbs above the pre-determined set point

Hydrocarbons – Any of a class of organic compounds composed only of carbon and hydrogen. The carbon atoms form the framework, and the hydrogen atoms attach to them. Hydrocarbons, the principal constituents of petroleum and natural gas, serve as fuels, lubricants, and raw materials for production of plastics, rubbers, solvents, explosives, and industrial chemicals.

HT  Heater Treater


  • The ability of a substance to attract and hold water molecules from the surrounding environment ID
  • Inside diameter (for vessel or piping)

HZ – horizontal shale completions

Initial Production of Well (IP) – Commissioned first flow

Inlet Diverter – Diverts the flow of the incoming fluids in a separation vessel to aid in the separation of liquids and gas

Interface Float – A weighted float designed to sink in oil and float in water

Liquid Desiccant Dehydration – A dehydration process in which water is removed from a gas stream through the use of a liquid desiccant, such as triethylene glycol (TEG). Within a contactor, the glycol encounters the stream of gas, removing the water from the gas. The glycol is circulated through a closed system between the contactor and regeneration system, where the water is boiled from the glycol. Once regenerated, the glycol circulates back to the contactor.

Low Pressure Control Valve – The low pressure control valve is a diaphragm operated valve designed to control flow in liquid or gas systems up to 300 psig (20.7 bar) working pressure from a 5 to 100 psig (0.34 to 6.9 bar) pneumatic actuating signal; it can be used for oil and water dump valves on low pressure separators and as burner valves for throttling or snap action service

Low Suction Makeup Gas – Gas usually taken from discharge of a compressor and sent back to inlet of the compressor to keep unit from going down on low suction pressure

Manway – Hole that allows access to the inside of a vessel. 

Mist extractor – A device, located in the gas separation section of a separation unit that removes liquid mist from the gas as the gas leaves the vessel. 

MBBL – One thousand barrels of water, crude oil, bitumen, condensate or natural gas liquids

MBD – One thousand barrels per day

MBOE – One thousand barrels of oil equivalent

MCF – One thousand standard cubic feet of natural gas; gas at 14.7 psia and 60oF (US standard)

Mechanical Oil Valve  The Mechanical Liquid Valve or Dump Valve is designed to work with a trunnion assembly to remove liquids from the vessel; this valve is dependent on the mechanical level to open or close

Metering Valve  Usually a manually-operated valve designed to establish a desired flow rate (liquid or gas) 

MMBBL – One million barrels of crude oil, bitumen, condensate, or natural gas liquids

MMBOE – One million barrels of oil equivalent

MMBTU – One million British thermal units

MMCF – One million standard cubic feet of natural gas; gas at 14.7 psia and 60oF (US standard)

Midstream Sector – The midstream industry processes, stores, markets, and transports commodities, such as crude oil, natural gas, and natural gas liquids (NGLs, mainly ethane, propane, and butane, and sulfur); the midstream provides the link between the oil and gas production areas and population centers where most consumers are located

Molecular Sieve – A material with very small holes of precise and uniform size; these holes are small enough to block large molecules and allow small molecules to pass

NYMEX – New York Mercantile Exchange

Natural Gas Processing Plant – A plant that uses a complex industrial process designed to clean raw natural gas by separating impurities and various non-methane hydrocarbons and fluids to produce what is known as pipeline quality dry natural gas

Net Acres – The percentage a company owns in an acreage with multiple owners

OD – Outside diameter (for vessel or piping) 

Oil Chamber – A compartment within a separator that accumulates oil skimming over the oil weir 

Oil Field – General term used to describe portion of the energy industry

Oil Outlet – A piping arrangement that directs oil out of the treater

Oil Weir – A dam-like structure in a vessel that maintains an oil level and allows oil to skim over into the oil chamber. 

Ounces Pressure Reducing Regulator  Control valve designed to limit downstream pressure from 1/2oz to 20lbs

Pilot  Control device that monitors a specific point and then sends a signal to a control device to open or close or maintain

Pilot Guard – On a line heater, the Pilot Guard monitors the pilot light to the burner tubes; if the pilot light is extinguished, the Pilot Guard will block instrument gas from reaching the burner controls, causing the system to shut down

Piston Balanced (or Cage Guided) – A device used to restrict fluid flow to one direction; the cage guided piston is balanced because upstream pressure communicates through ports from the bottom side to the top side of the piston, cancelling out the opposing forces (or balancing the piston)


  • A basic component of the sucker rod pump that serves to draw well fluids into the pump
  • The rod that serves as a piston in a reciprocating pump

Pneumatic Level Switch – Snap-acting stainless steel switch with a seal-less design, keeping the fluid isolated from the pneumatics; when activated, depending on service required, allows or disallows other devices to work

Pressure Drop – A decrease in pressure from one point in a pipe or tube to another point downstream

Pressure Relief Valve – A safety valve that opens at a preset pressure to relieve excessive pressure within a vessel or line. 

Production – The phase of the petroleum industry that deals with bringing the well fluids to the surface and separating them and storing, gauging, and otherwise preparing the product for delivery

PS2 – The PS2 is an electro-pneumatic positioner designed by Siemens that allows precise positioning of pneumatic valves. As the Kimray PS2 sends a pneumatic signal to the control valve to actuate the valve, the stem position is monitored. This comparison of the set point and the actual valve stem position value takes place electronically in a micro-controller. This controller can be operated either manually or remotely. It utilizes binary inputs and outputs and has multiple functions including diagnostic and blocking.

PSI – Pounds per square inch

PSIA – Pounds per square inch absolute (includes atmospheric pressure, which is 14.7 psi)

PSIG – Pounds per square inch gauge (reading on a gauge that is atmospheric pressure (14.7 psi) less)

Reboiler – A component used in liquid desiccant dehydration to boil the glycol-water mixture and separate the glycol from the water

Refinery – An industrial processing plant where crude oil is processed and refined into more useful products such as petroleum naphtha, gasoline, diesel fuel, asphalt base, heating oil, kerosene, and liquefied petroleum gas

Regeneration – To form or create again; in natural gas dehydration, the process of regeneration is used to restore the absorbent or adsorbent back to purity for reuse

Regulator – A device that regulates the flow of gas or liquid

Secondary Recovery

  • The use of water-flooding or gas injection to maintain formation pressure during primary production and to reduce the rate of decline of the original reservoir drive
  • Water-flooding of a depleted reservoir

Sense Line – Usually refers to tubular line that connects sense point to pilot

Sense Line Protector – The sense line protector is an adjustable, self-resetting, pressure limiting device to protect instrumentation from over pressurization and subsequent damage; specifically, it is designed to protect pilots on high pressure regulators, blocking the sense line or supply pressure to a device when it exceeds the adjustable limit of 300 psig and reopening when inlet pressure drops below the limit

Sight glass – A device on the outside of a vessel that indicates the liquid level. 

Snap Trim – Type of ball and cone trim; used in erosive service or metering service

Solid Desiccant Dehydration – A dehydration process that utilizes the principle of adsorption or absorption to remove water vapor from a stream of gas. An adsorbent, such as molecular sieves or silica gels, is placed in an adsorption vessel. As gas flows through the adsorption vessel, the water vapor coalesces on the surface of the adsorbent. Once the adsorbent becomes fully saturated, it is taken out of service for regeneration. An absorbent, such as halide salts, utilizes the same contact pattern. However, the end result is a brine solution that is discarded.

Spring Loaded Back Pressure Regulator  On a free water knockout, the Spring Loaded Back Pressure Regulator controls the gas pressure along with the oil level in the vessel

Stack – A piping arrangement that draws spent gasses out of the firetube and disperses them at a safe level above a heater vessel. 

Stem Guided – Control valve type in which ball and cone are attached to a stem which is guided through the packing gland

Suction Controller – Control valve used to provide constant pressure to the compressor inlet

Supply Gas Regulator  Instrument gas regulator used to provide gas or air at a set pressure

T-12 Thermostat

  • On a dehy unit, the T-12 Thermostat monitors the reboiler temperature and provides pneumatic output proportional to the temperature
  • On a compressor, the T-12 Thermostat monitors the temperature of the output of the compressor and activates the shutters
  • On a heater treater, the T-12 Thermostat monitors the emulsion and regulates the burner flame to maintain a constant temperature

TCF – One trillion cubic feet of natural gas

Three Way Control Valves – The three way valve is used to divert flow from one pipeline to another; for bypass applications where either part of the fluid or all of the fluid is passing through the valve and is diverted through either or both of the outlets, or as a mixing valve for combining two fluid streams and discharging through a common outlet port

Treater Valve  The Treater Valve is a floatless level control valve; typical installation will include the water leg and oil leg of a heater treater

Triethylene Glycol – A colorless, odorless, viscous liquid used as a liquid desiccant for dehydrating natural gas

Trunnion Assembly – Used on free water knockouts and separators, the trunnion assembly is used to maintain a constant water level

Two-Phase Separator – A vessel that separates the well fluids into gas and total liquid. A two-phase separator can be horizontal, vertical, or spherical. The liquid (oil, emulsion) leaves the vessel at the bottom through a level-control or dump valve. The gas leaves the vessel at the top, passing through a mist extractor to remove the small liquid droplets in the gas.

Turbine Meter – Type of meter used to measure fluids or gas; turbine vane tips are counted by magnetic pick-ups as they pass by, and that number is translated to a digital read out

Upstream Sector – The upstream industry finds and produces crude oil and natural gas; the upstream is sometimes known as the exploration and production (E&P) sector

Water Bath – Fluid contained in a heater treater into which the firetube is immersed.  

Water Leg – A component of a separation unit that maintains a constant water level inside the vessel. 

Water Outlet – A piping arrangement that directs water out of the vessel. 

Wet (Rich) Natural Gas – Natural gas that contains an appreciable proportion of hydrocarbon compounds heavier than methane (e.g., ethane, propane, and butane)

Wet Gas – Natural gas that contains less methane (typically less than 85% methane) and more ethane and other more complex hydrocarbons

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