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Oil and Gas Glossary
Appraisal well: A well which is drilled when conducting an appraisal drilling programme, to determine the reserves, production rate and physical extent of a field.
Associated gas: Natural gas which is produced with crude oil at the same reservoir.
Barrel: A measurement of a unit of volume, used to measure petroleum and related products.
BBL: A barrel of oil. One barrel of oil is approximately 35 imperial gallons or 159 litres.
BCF: A billion cubic feet., used to measure the volume of natural gas.
BCM: A billion cubic metres. One billion cubic metre (BCM) is equivalent to 35.31 cubic feet.
Bit: A drilling tool used to cut a hole.
Block: An area of land awarded to drilling and exploration companies, usually measured in 1000s of sq. kilometers.
Blow-out: When well pressure exceeds the ability of the wellhead valves or drilling mud, which causes oil and gas to 'blow' to the surface.
Borehole: The hole made by the drill, which includes the open hole or uncased portion of the well. It can refer to the inside diameter of the wellborn wall.
BTU: British thermal unit. A measurement unit of the heating value of a fuel.
Capex: Capital expenditure.
Casing: A steel pipe used to seal off fluids from the hole and provide structural support.
Christmas Tree: The set of spools, fittings and valves that are connected to the top of a well, used to control and direct the flow of formation fluids from the well.
Condensate: Hydrocarbons that are in the gaseous state and become liquid when temperature or pressure is reduced.
Coring: Taking rock samples from a well by using a core barrel.
Crude oil: Refers to liquid or unrefined petroleum.
Cuttings: Chips of rock from the formation that is brought to the surface for geologists to analyse.
Derrick: Refers to the structure which supports the drillstring and crown blocks of a drilling rig. Usually pyramidal in shape, they offer a great strength-to weight ratio.
Downstream: Operations that take place after the production phase, through to the sale to consumers, including refining and distributing.
Drilling rig: A drilling unit, not fixed to the seabed, such as a jack-up unit, semi-submersible or a drillship.
E&A: Exploration and appraisal.
E&P: Exploration and production, the companies who find, augment, and produce oil and gas.
EOR: Enhanced oil recovery. A process of recovering oil that uses sophisticated techniques to increases the amount of oil that is removed from a reservoir. The process usually involved injecting liquid or gas.
Exploration well: Drilling which is carried out to determine whether oil or gas is present. Sometimes called a wildcat well when drilling in a place where no oil and gas production currently exists.
Field: Field or oil field is an accumulation of hydrocarbons or alternative mineral resources in the subsurface. Consisting of a reservoir that traps hydrocarbons, covered by a sealing rock.
FPSO: Floating Production Storage and Offloading, a floating vessel that is designed to process and store hydrocarbons either produced by itself or nearby platforms. The oil would then be offloaded onto a tanker or sometimes through a pipeline.
Fracturing: The process of pumping fluids at high pressure to create fractures which break down rock in order to increase production rates from a reservoir.
Gas injection: The process of pumping separated associated gas back into a reservoir in order to maintain pressure or for conservation purposes.
GIS: Geographic Information System, which assembles, stores, manipulates and displays geographical information.
Horizontal well: A high angle well which is usually greater than 85 degrees of inclination.
Hydrocarbon: An organic compound comprising of hydrogen and carbon, which can occur as liquids, solids or gases. Common hydrocarbons are natural gas, coal and oil.
Injection well: A well where fluids are injected as opposed to produced, with the primary objective of maintaining reservoir pressure. The two main types of injection are water and gas.
Lay barge: a barge which lays submarine pipelines.
LNG: Liquefied natural gas. Naturally occurring gas (mainly methane) which is cooled and liquefied for transportation.
LPG: Liquefied petroleum gas (usually consisting of propane or butane, or mixtures thereof). A light hydrocarbon material which is gaseous at atmospheric temperature and pressure and kept in its liquid state by pressure in order to enable storage, handling and transport.
Mmboe: A million barrels of oil equivalent.
Mmcfd: Millions of cubic feet per day, of gas.
Mud: A mixture made up of base substance and additives. It’s used to counteract the natural pressure of the formation and lubricate the drill bit.
Operator: Refers to the company with legal authority to undertake the production of hydrocarbons and drill wells. They often act on behalf of a consortium of which they are part.
Opex: Operating expenditure.
Permeability: Refers to a rock’s ability to transmit fluids, the flow of a liquid through the port spaces and into a wellbore. It is usually measured in millidarcies or darcies.
Petroleum: Typically refers to liquid crude oil, it is a complex mixture of naturally occurring hydrocarbon compounds which are found in rock. The colour, odour, sulphur content, gravity and viscosity varies considerably in petroleum found from different areas.
Platform: An offshore structure permanently fixed to the seabed.
Primary recovery: Recovering oil or gas by using just the natural pressure in the reservoir.
PRM: Permanent Reservoir Monitoring, a method of subsea terrain monitoring where monitoring equipment is always on-site, allowing an oil company to better manage oil reservoirs.
Probable reserves: Reserves estimated to have a more than 50% chance of being economically and technically producible, but which has not yet been proven.
Proven reserves: Reserves which, based on available evidence, are mostly certain to be economically and technically productive, usually considered to have a better than 90% chance of being produced.
Recoverable reserves: A proportion of the gas and oil in a reservoir which is able to be removed using available techniques.
Reservoir: A formation where oil and gas has accumulated underground, consisting of a cap rock to prevent it from escaping and a porous rock to hold the gas or oil.
Roughneck: A floor hand or drill crew member, who works on the derrick floor under the direction of the driller. They make or break connections of the drill pipe when running or pulling a drillstring.
Roustabout: A drill crew member who assists in the general operation around the rig, and handles the loading and unloading of equipment.
Secondary recovery: Artificially recovering oil or gas by increasing or maintaining the pressure. Methods include injecting gas, water or other substances.
Seismic: Using soundwaves to targeted at the surface to determine the subsurface geological structures.
Shutdown: Refers to a hiatus in production where the platform ceases to produce to enable maintenance work.
Spud: Drilling the first part of the well.
Suspended well: A well that has been temporarily shut off.
Tcf: Trillion Cubic Feet, of gas.
Toolpusher: The second-in-command of a drilling crew, who is responsible for the running of the rig and monitoring the availability of all vital equipment.
Topsides: The superstructure of a platform.
Upstream: The production and exploration portions of the oil and gas industry.
Waterflooding: Injecting water into a reservoir to push out additional oil contained in the rock.
Well log: a log of the geological formation during drilling, including any technical details.
Workover: Remedial work done to the equipment in the well or the pipework, and can also refer to projects that attempt to increase the flow rate.
WTI: Stands for West Texas Intermediate, a type of crude oil used for price benchmarking.