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Oil and Gas Jargon: Your Comprehensive Glossary

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​Navigating the intricacies of the oil and gas industry can be a daunting endeavour, especially for newcomers or individuals transitioning from other engineering fields. The multitude of specialised terms can leave you feeling overwhelmed. That's why we've curated this Oil and Gas Glossary—a valuable resource to help you master the language of the industry.


Abandon: Plugging and abandoning a well at the end of its usable life; cleaning up the wellsite and salvaging material and equipment.

Abatement: Techniques used to reduce pollution and environmental impact.

Acreage: Land that has been leased for exploration or over which the company holds mineral rights.

Annulus: The space between the borehole wall and casing, between two sections of casing, or between casing and tubing.

Appraisal Well: A well drilled to determine the extent and potential production rate of a field.

Aquifer: An underground layer of permeable rock or material that holds water and can be tapped for extraction.

Azimuth: The direction in which a horizontal well is drilled relative to magnetic North.

Barrel: A standard measurement unit for oil and its derivatives. (1 ton ≈ 7.3 barrels)

Bit: The drilling tool responsible for cutting the wellbore.

Bitumen: Naturally occurring flammable substances consisting of hydrocarbons and low oxygen content.

Block: A subdivision of a quadrant measuring approximately 10 x 20 km.

Blow-down: Simultaneous production of gas and condensate.

Blow-out: A situation where the wellhead valves cannot control the pressure, resulting in uncontrolled release of oil or gas at the surface.

Borehole: The hole created in the earth's crust by the drill bit.

BOP (Blow-out Preventer): A set of high-pressure valves designed to shut off uncontrolled flow during drilling.

Brine: A mixture of saltwater and chemicals, often produced after hydraulic fracturing and requiring treatment due to high levels of solids and metals.

Casing: A pipe cemented into the wellbore to provide support and seal off fluids.

Casing String: Tubing which lines a well after drilling.

Casinghead Gas: Gas produced with oil in oil wells.

Catalytic Cracking: A refining process that uses a catalyst to break down large hydrocarbon molecules.

CCS (Carbon Capture and Storage): A process that captures carbon dioxide emissions, removes them from the atmosphere, and stores them, typically underground.

Cementing: Pumping cement into the wellbore to seal or set plugs for various purposes, including abandonment.

Christmas Tree: Valves and fittings installed atop the casing to control production.

Commercial Field: A field judged to be worth developing due to profitability.

Completion: The installation of wellhead equipment to enable production.

Compressor Station: A facility used to increase the pressure of gas for transportation through pipelines.

Condensate: Hydrocarbons that are gaseous in the reservoir but become liquid when pressure or temperature decreases.

Conventional Resources: Oil and gas deposits that are easily accessible and recoverable.

Coring: Taking rock samples using a core barrel; a tool specialised for this purpose.

Core Barrel: A specialised tool used for taking rock samples (cores).

Cracker: A facility that employs high-temperature cracking to break down petroleum hydrocarbons and produce alkenes.

Cranes Barge (Derrick Barge): A floating barge equipped with cranes to lift equipment onto offshore platforms.

Crude Oil: Unrefined liquid petroleum.

Cuttings: Pieces of rock used by geologists to obtain information.

Derrick: A tower, typically made of open steel framework, which houses most of the drilling controls.

Development Phase: The period in which a field is brought into production by the drilling of wells.

Deviated: Wellbore direction change.

Directional Drilling: The technique of drilling non-vertical wells to access specific reservoir targets.

Downstream: The refining, processing, purification, marketing, and distribution of oil and gas products.

Drilling: Boring holes.

Drilling Rig: A unit used for drilling, such as a drillship or jack-up unit.

Dry Gas: Gas composed mostly of methane with no or very little heavy hydrocarbons.

Dry Hole: A well that does not yield any productive oil or gas.

Enhanced Recovery (EOR): Techniques aimed at increasing the recovery of oil and gas from a reservoir after primary production.

Environmental Assessment: A study to assess the potential environmental impacts of a project.

Equivalent Barrels: The energy content equivalent of one barrel of oil, expressed in terms of natural gas and liquids.

Ethylene: A colourless, flammable gas widely used in the chemical industry.

EUR (Estimated Ultimate Recovery): The total anticipated amount of recoverable reserves.

Exploration Drilling: Drilling conducted to determine the presence of hydrocarbons.

Exploration Phase: The period covering the search for oil / gas through surveys and exploration drilling.

Exploration Well: Wildcat well, a well drilled during the exploration phase.

Field: The area under which a reservoir lies.

Fishing: Retrieving objects from the borehole.

Flaring: The safe burning of natural gas for when there is no way to transport to market or use for other purposes. This is being reduced in response to environmental concerns.

Flowback Water: Water generated during oil and natural gas exploration and development, prior to the well producing.

Formation: A distinct rock layer with unique characteristics.

Formation Pressure: The pressure within the reservoir.

Fracturing (Hydraulic Fracturing or Fracking): The process of injecting high-pressure fluid into a formation to enhance production.

Fracturing Fluid: A mixture of water, sand (proppant), and additives used in hydraulic fracturing.

Fugitive Emissions:Emissions (leakages) of gases or vapours from pressurised equipment.

GIS (Geographic Information Systems): Software tools used to store, analyse, and manipulate geographical data.

GHG (Greenhouse Gas): Gases like carbon dioxide and methane that contribute to the greenhouse effect and global warming.

Gusher: A well that releases oil at high pressure, often leading to uncontrolled flow at the surface.

GWP: Global Warming Potential, how much heat a greenhouse gas traps in the atmosphere over a period, shown as a multiple of that for carbon dioxide which is represented by 1.

Heavy Oil: Highly viscous oil which does not easily flow.

Held By Production: The legal process which allows companies to extend the terms of the lease by paying royalties to the rights owner for the life of the well.

Horizontal Drilling: A technique where the wellbore is turned horizontally to access hydrocarbons at the same depth.

Hydrocarbon: A compound consisting solely of hydrogen and carbon atoms.

Hydrostatic Pressure: The pressure exerted by the weight of a fluid column in a well.

Impoundment: A contained body of water or sludge, often created by barriers.

Independent: A company involved only in E&P and possibly transportation, but not refining of oil.

Infill Wells: Wells drilled into the same reservoir as each other to limit the distance travelled by oil / natural gas, speeding up recovery.

Injection Well: A well used for pumping water or gas into the reservoir.

Integrated Company: A major oil company involved in all aspects of the industry, from exploration and production to refining and marketing.

Jacket: The lower part of an offshore platform.

Land Man: A job role working for an E&P company, negotiating the terms of the lease agreement.

Lay Barge: A barge for laying pipelines.

LCA: Life Cycle Analysis, a methodology used to interpret environmental flows to and from the environment over the process life cycle.

LNG (Liquefied Natural Gas): Natural gas that has been converted into liquid form for ease of transport.

LPG (Liquefied Petroleum Gas): Petroleum gases held in liquid form under pressure for storage and handling.

Mechanical Integrity Test: A test to ensure the integrity of casing.

Methane: The primary component of natural gas, known for its flammability and greenhouse gas properties.

Midstream: The transportation, measurement, and processing of oil and gas from the well.

Mineral Rights: Legal rights allowing exploration and extraction of minerals in a specific area.

Moonpool: A hole in a drillship or semi-sub used for drilling and diving operations.

Mud: Drilling Fluids, base substance plus additives, which is used both for counteracting pressure and lubricating the drill bit.

Natural Gas: Naturally occurring gas which is found alongside crude oil.

Natural Gas Liquids: Hydrocarbons found in natural gas which can be isolated as LPG and natural gasoline.

Net Acres: The amount of the lease owned by a company.

Oil: A mixture of liquid hydrocarbons of different molecular weights.

Oil in Place: Estimation of the amount of oil in reservoir (both recoverable and non-recoverable).

Oil Pool: An underground reservoir or trap containing oil.

Oilfield Services: Companies providing specialised services to support oil and gas exploration, production, and development.

Operator: The company drilling wells and producing oil.

Payzone: Rock in which oil and gas are found.

Permeability: The extent to which fluid can flow through the pore and into the well.

Petroleum: Generic name for hydrocarbons.

Pipeline Inspection Gauge (PIG): In this role a pipeline inspection gauge performs maintenance in a pipeline.

Pipeline: Tubing or piping used for transporting oil and gas over long distances.

Play: An area where prospects with similar characteristics accumulate.

Platform: A permanent offshore structure used for drilling, production, or other operations.

Plugging of Well: Sealing off of fluids to stop fluid from one stratum from escaping into another or from surfacing.

Pooling: Land pooling, the legal process allowing E&P companies to compel land/mineral rights holders to lease or sell their land and/or mineral rights for exploration, drilling, or pipeline installation if enough surrounding neighbours have already agreed.

Porosity: The percentage of void to solids in a porous rock.

Possible Reserves: Reserves with less than 50% chance of being producible.

Primary Recovery: The initial production from a reservoir driven by natural pressure.

Probable Reserves: Reserves with more than a 50% chance of being producible.

Processing Plant: A plant which processes natural gas into propane’s, butanes and other products.

Produced Water: Overboard water, water or brine produced from oil and gas wells.

Production Well: A well capable of producing enough oil and gas to justify commercial exploitation.

Propane: A colourless, flammable gas in petroleum and natural gas. open, allowing oil and natural gas to flow.

Proven Field: A field whose reserves have been determined.

Proven Reserves: Reserves which have been proven to be viable, both economically and technically.

Recompletion: Entering an existing wellbore to establish production from a new zone.

Recoverable Reserves: Recovery Factor, the proportion of oil or gas which can be removed using current techniques.

Redrill Footage: A second hole drilled in close proximity to a failed first hole.

Re-enter: Return to an abandoned well.

Refinery: The facility where crude oil is processed into more useful products.

Reserves: Estimated remaining quantities of oil and gas anticipated to be producible.

Reservoir: An underground rock formation containing hydrocarbons.

Resources: Estimations of quantities of oil and gas, recoverable and unrecoverable; discovered and undiscovered.

Rig: The structures and equipment used in drilling a well.

Rig Down: Disassembling field equipment for transport or storage.

Rig Up: Assembling field equipment to get ready for use.

Riser: In drilling, a pipe between a seabed BOP and floating drilling rig. In production, the pipework joining the wellhead to the Christmas tree.

Roughneck: Job role, crew member who works on the derrick floor, typically screwing together sections of drillpipe.

Roustabout: Job role, crew member who loads and unloads equipment and assists with general rig operations.

Royalty Payment: The money paid by E&P companies to the mineral rights owner of a well.

Seal: A rock unit which inhibits the mixing of fluids and gases between adjacent geologic units, either upwards or laterally.

Seal Formation: A rock layer that prevents fluid migration between different geologic units.

Secondary Recovery: Techniques that use injected substances (e.g., gas or water) to increase reservoir pressure and improve production rates.

Shale: Fine-grained sedimentary rock formed by the consolidation of clay, mud or silt.

Shale Gas: Natural gas which can be generated and trapped within shale units.

Shale Oil: Liquid petroleum which can be generated and trapped within shale units.

Shut In Well: A well which is capable of producing but is not at the moment.

Shutdown: A maintenance period during which time production ceases.

Sour Gas: Contaminated natural gas with an unpleasant smell.

Source Rock: Rocks containing hydrocarbons.

Spacing: The distance between wells producing from the same reservoir.

Spud-in: Drilling the first part of a new well.

Stripper Production: The last stage of production a well, usually with low rates of production, as little as a barrel per day.

Surface Location: The location of a well.

Surface Reclamation: Restoration of land used for drilling or production; regrading and vegetating the area.

Suspended Well: A well which has been temporarily capped.

Tension Leg Platform: A type of platform especially useful for deep waters, whereby the surface platform is tethered to the ocean floor by flexible steel tendons.

Tight Gas: Natural gas produced from relatively impermeable rock, usually through hydraulic fracturing or other technologies.

Tool pusher: Job role underneath Drilling Superintendent. They are responsible for day-to-day running of the rig and ensuring availability of equipment.

Top hole: Vertical portion of the hole.

Topsides: Superstructure of a platform.

Trap: A geologic feature which holds hydrocarbons or injected carbon dioxide, caused by the breaking of a rock plane.

Ultrasonic Meter: Ultrasound used to measure flow rates from outside the pipe.

Unconventional Reservoirs: Reservoirs with such low permeability that horizontal hydraulic fracturing other advanced techniques must be utilised for the well to be commercially viable.

Undiscovered: Resources which exist outside of known fields or in undiscovered pools.

Upstream: The exploration, drilling, and production phases of the oil and gas industry.

Well: The hole drilled in the earth for the purpose of finding and/or producing oil and/or gas.

Wellhead: The structure at the surface of the well that provides the interface for drilling and production equipment.

Wellhead Revenues: The total value of oil and gas at the wellhead (prior to refinement).

Well Log: A record that documents drilling and well data.

Wet Gas: Gas which contains liquids.

Workover: Attempts to increase flow rate, or remedial work to equipment or pipework.

Wellbore: The hole drilled into the earth for oil and gas exploration.

Workover: Remedial activities performed to increase well production rates or address equipment issues.

Mastering Oil and Gas Lingo

With this Oil and Gas Glossary at your disposal, you're well-equipped to decode the industry's terminology

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