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An assembly of valves, spools, and fittings for an oil well, designed to control the flow of wellbore fluids during production.

A large, specialized valve used to seal, control and monitor oil and gas wells to prevent blowouts, or the uncontrolled release of crude oil/natural gas from a well.

Tubular steel pipe that is set in an oil or gas well to protect and support the well stream from the surrounding earth and to prevent the well from caving in.

A circulating fluid composed of water, oil, clay and chemicals used in the drilling of boreholes. It cools and lubricates the drill bit, carries the cuttings to surface and balances the formation pressure.

The pressure in the subsurface formation, which can be normal, abnormal, or subnormal. It is a critical parameter in drilling and production operations.

The process by which a well is enabled to produce oil or gas through the casing and cement sheath and into the wellbore by making holes or perforations in the casing.

A downhole tool that is run and set inside the casing to isolate the annulus from the production conduit, enabling controlled production, injection or treatment.

The surface termination of a wellbore that includes fittings, valves and adapters for connecting drilling and production equipment.

An influx of formation fluids into the wellbore during drilling operations, typically due to the pressure in the wellbore being less than that of the formation fluids.

The procedure performed at the end of a well's productive life whereby the well is sealed with cement plugs to ensure that no leak of reservoir fluids can occur.

The practice of making detailed records (logs) of the geological formations penetrated by a borehole, to help in the planning and evaluation of subsurface conditions and resources.

The initial drilling operation in the construction of a new well, involving the setting of the first drill bit into the seabed or ground to begin drilling.

An exploratory oil well drilled in unproven or semi-explored areas, not adjacent to known oil or gas fields, with the aim of finding a new petroleum reservoir.

Natural gas or any other gas containing significant amounts of hydrogen sulfide (H2S), which is toxic and corrosive, requiring special handling and treatment.

Pipeline that carries oil, gas or water that is produced from the well to processing facilities or storage tanks.

A subsurface pool of hydrocarbons contained in porous or fractured rock formations and trapped by geological features.

The hole drilled by the bit that forms the well. This is the inside of the circular hole in the ground, regardless of what is used to line it or how deep it is.

A tower-like structure located over the wellbore that holds the drilling equipment such as the hoist and pulley systems used to lower and raise equipment and tools down the well.

The process of making a well ready for production after drilling operations have concluded, which includes the setting of casing, cementing and perforating.

Sections of steel tubes that are screwed together to form a drill stem or tubing string, which is used to drill down into the earth's crust.

A bend or curve in the wellbore typically caused by drilling at an angle from the vertical. It can be intentional (as in directional drilling) or unintentional and may cause problems with running tools and casings.

A well stimulation technique involving the fracturing of bedrock formations by a pressurized liquid to increase hydrocarbon flow. This process creates fractures from the wellbore to the surrounding rock.

A mechanical device on a drilling rig that provides clockwise torque to the drill string to facilitate the process of drilling a borehole. It is an alternative to the traditional rotary table.

A technician who records and monitors the drilling parameters and the geological formations encountered while drilling, typically analyzing the cuttings and drilling mud.

The mechanical section of a drilling rig that contains the spool, whose main function is to reel out and reel in the drilling line to lift or lower the drill string and drill bit.

The column, or string, of drill pipe with attached tooling and drilling bit that transmits fluid and rotational power from the surface to the drill bit at the bottom of the wellbore.

A device with an orifice that is installed in a line to control the flow rate or downstream system pressure. Chokes are often used in the context of managing the production rate of a well.

A long metal pipe spooled on a large reel which is used for interventions in oil and gas wells, and sometimes as production tubing in depleted gas wells.

An operation to retrieve an object that has become lost or stuck in the wellbore, using special tools and techniques.

A casing string that does not extend back to the wellhead but is hung off or attached to the bottom of a previous casing string. Often used to save costs or reach deeper formations.

An influx of nitrogen gas into the wellbore during drilling, which can expand rapidly and lead to loss of well control if not correctly managed.

A region with an abundance of oil wells extracting petroleum (crude oil) from below ground. Oilfields are normally associated with other resources like natural gas.

The process of cleaning a pipeline using devices called 'pigs' that are inserted to scrape or brush the sides of the pipe or to seal the pipeline and remove built-up fluids or deposits.

A hole beside the wellbore that is used to temporarily store equipment on the rig floor, such as drill collars, that is not currently needed in the hole.

A method of artificially lifting fluids from a well, wherein a swab is run into the tubing down to the desired depth and then pulled out quickly to create a lower pressure that induces fluid flow from the formation.

A permeable layer within the formation, that 'steals' the drilling fluid or injected fluids from the target zone, which can lead to complications in drilling and well completion.

A technique where the pressure in the wellbore is kept lower than the pressure of the formation being drilled to minimize formation damage and achieve a higher rate of penetration.

A measure of a fluid's resistance to flow. In the oilfield, it affects how easily crude oil and other fluids can be pumped through pipes and how well they will clean a wellbore.

The ratio of water produced compared to the volume of total fluids produced from a well. High water cuts can indicate nearing the end of a well's productive life.

The process of making a well ready to produce oil or gas, including the installation of downhole equipment such as the production tubing and associated hardware.

The process of preventing crossflow between different layers of the formation, typically by using tools such as packers to isolate specific sections of the wellbore.

A type of blowout preventer (BOP) that is installed at the top of the wellbore and designed to close around the drill string, casing or open hole to prevent the escape of reservoir fluids.

A common type of artificial lift system also known as a 'nodding donkey' or 'pumping unit' used to mechanically lift fluids from a well when there is insufficient pressure to produce naturally.

The process of placing a cement sheath around a casing string, which provides zonal isolation and protects freshwater aquifers, and can also secure the casing in place.

A situation where a portion of the drill string becomes stuck in the well bore due to differential pressure across the pipe, impeding or stopping drilling operations.

A condition or setting on drilling rigs or production platforms where equipment is operated in a way to minimize fuel consumption or energy use without significantly affecting performance.

The pressure at which the formation rock will fail and fracture. It is a critical parameter during drilling operations to maintain well control and avoid inducing fractures in the formation.

A tool with a catchment area used during drilling operations to retrieve small pieces of debris, or 'junk', from the bottom of the wellbore.

A device fitted to the rotary table through which the kelly passes, allowing the rotation and vertical movement needed during drilling while sealing the upper end of the wellbore.

A situation in drilling where the drilling fluid is lost to the formation due to excessive permeability or fractures, which can compromise drilling operations and well integrity.

An adaptive drilling process used to more precisely control the annular pressure profile in the well. MPD is used to manage the downhole pressure to mitigate risks and optimize drilling.