The complexities of the oil and gas industry can make keeping up with all the terms and definitions related to drilling difficult. To simplify things, we’ve compiled a glossary of the most important terms related to drilling and to the oil and gas industry.
Oilfield Glossary of Terms
To pause or stop drilling operations or production from a well. Reasons for abandoning are if a well is a dry hole or if it’s not producing enough to be kept active.
To increase the flow of oil or gas in drilling, hydrochloric acid can be pumped into the well. The acid works to break down limestone, reducing the restrictions the oil or gas was previously facing to increase flow.
Used to describe any method for retrieving oil from a well and bringing it to the surface after the well ceases to produce.
Natural gas that’s created with crude oil from the same resevoir.
The part of a separation vessel used to temporarily slow the flow of fluids; needed when attempting to separate oil and water.
A steel bar that supports the swivel and connects it to the hook; resembles the handle of a bucket.
Barrel of Oil Equivalent (BOE):
The amount of oil barrels produced from a site each day.
A steel bar that supports the swivel and connects it to the hook. Resembles the handle of a bucket.
An extremely viscous form of crude oil that contains sulfer and other metals; to be produced, bitumen must be heated or combined with lighter hydrocarbons.
An oil and gas limited partnership that has not comitted to a single lease or property yet.
Occurs when down-hole pressure gas is not properly balanced with the weight of the drilling mud; the uncontrolled flow of gas, oil, or other fluids.
As a noun, a bore is the inside diameter of a pipe or drilled hole. As a verb, bore means to penetrate a surface with a rotary tool.
An acronym for British Thermal Unit, BTU is a measurement to describe the amount of heat generated from burning oil or gas.
A rope, wire or braid of strong fibers.
A well that has the casing already inserted. The opposite of a cased hole is an open hole.
A steel pipe that’s placed in an oil or gas well after drilling is completed to prevent the well hole from caving in. Casing also prevents fluids from moving from one formation (like groundwater) to another and helps in well control.
Drill Rig: The machinery that’s used to drill oil and gas wells. There are two types of drill rigs: rotary and cable tools, with rotary drill rigs being more efficient.
A large wrench used for turning casing tubulurs when making up or breaking out casing.
A long, but small in diameter pipe that is used to replace jointed pipes in certain types of drilling, completion, and workover operations.
A well that produces enough to pay for it’s production costs and leave enough oil and gas to be sold for revenue.
Used to describe all activities between drilling to casing point and putting the well to production. Includes cleaning out the well bore, setting the casing and tubing, adding surface equipment, and perforating the casing.
An engine that is used to increase natural gas pressure so that it can more easily flow through the pipeline.
Oil’s form as it comes directly from the ground; it’s a mixture including naturally occurring liquid hydrocarbons.
The loss in mineral deposits as the well is produced.
Depletion (Gas) Drive:
When drilling into an oil source, free gas in the well expands and allows the oil to flow into wellbore and up to the surface; also known as a solution gas drive.
A well that’s drilled in a proven oil or gas reservoir at the depth of proven productivity.
A removable, steel, serrated piece that fits into the jaws of tongs. Die inserts grip drill pipes, drill collars and casing while the tongs are making up or breaking out pipe.
A tool used to shape, form, or finish other tools or pieces of metal.
An internal-combustion engine frequently used for powering drilling rigs. A diesel engine is a high-compression engine that draws air into its cylinders and compresses the air to very high pressures; ignition then occurs as fuel is injected into the compressed, hot air. Combustion takes place in the cylinder above the piston; the combustion then powers the piston.
Also called a dip meter or dip log, this surveying method determines the direction and angle of a formation dip in relation to the borehole to provide geological structure of the formation.
Drilling in the opposite direction of a wellbore from the vertical. Directional drilling uses rotary steerable tools to move around rocks or other obstructions to continue drilling.
The industry that includes: oil refineries, petrochemical plants, petroleum products distributors, retail outlets and natural gas distribution companies. The Downstream operates anywhere oil, plastics and natural gases are used.
The cutting or boring element used to access oil or gas in the drilling process. Not only are most bits roller-cone bits, but the drill bit also typically includes both the cutting element and the circulating element.
A heavy steel tube that’s placed between the drill pipe and the bit in the drill stem. Drill collars are used to add weight to the bit to make drilling easier.
A piece of seamless tubing used to rotate the bit and circulate the drilling fluid. The pipe joints are usually about 30 feet long and are joined together by tool joints.
The machinery that’s used to drill oil and gas wells. There are two types of drill rigs: rotary and cable tools, with rotary drill rigs being more efficient.
Transmits fluid and rotational power from the kelly bushing to the drilling collar. As the name suggests, the drill string is a column, or string, with attached tool joints.
Electronic Flow Meter:
Monitors the amount of oil and gas flowing from a wellhead; measurements are expressed in real time, actual flow, cumulative flow, and historical data.
Hinged steel devices with manual operating handles that are attached to rotary and top drive rigs. Crew members latch elevators onto tool joints to operate them.
Estimated Ultimate Recovery (EUR):
An estimation of the cumulative volume of reserves that will be discovered in a specific reservoir.
A well created for the purpose of finding oil or gas in a previously unproductive area.
The process of a fluid (usually crude oil, diesel or water) being pumped into the reservoir to break the reservoir rock open.
Free Water Knockout (FWKO):
A vertical or horizontal separator used to separate gas, oil and water. The water is removed to prevent corrosion and the formation of hydrates or tight emulsions.
A well that primarily produces gas.
Crude oil with an API gravity of 20 degrees or less. It tends to have a high viscosity and hinders an easy flow of oil.
A drilling technique that consists of vertical drilling down to a particular depth, and then involves turning at a right angle to drill horizontally within a specified reservoir.
Operated, moved, or effected by water or liquid.
A weighted float created to sink in oil and float in water; used as a testing tool.
A single section of drill pipe, casing or tubing that’s usually about 30 feet long.
Joint Operating Agreement (JOA):
A written agreement between multiple land operating partners that details how the land will be developed, who will pay for the exploration and development, and when this development will happen.
A long hollow steel bar that’s used to connect the upper end of a drill string. Kelly bushing is a sleeve in the rotary table that allows the Kelly to freely move up and down during drilling. Kelly bushing also plays a part in the measurement of well depth, as well depth is measured from the Kelly bushing, down to the bottom of the well.
The person who manages land leasing and land damages for oil and gas companies.
The agreement formed by the owner of the property and the interested exploration and development party. The property owner gives the lessee exclusive rights to search for and extract any minerals found on the property.
The person who acquires the rights to drill for oil or gas on a piece of land.
The landowner who grants access for drilling for oil or gas on their land, known as a mineral lease.
Low Pressure Control Valve:
A diaphragm used to control the flow of liquid and gas; often found in oil and water dump valves. Used in systems with working pressures up to 300 psig.
The acronym that represents one thousand barrels of oil equivalent.
Mechanical Oil Valve:
Also known as a Mechanical Liquid Valve or a Dump Valve, it is designed to work together with a trunnion assembly to remove liquids from the vessel. It’s controlled by a mechanical level.
The sector within the industry between oil production and the consumers that processes, stores and markets crude oil and natural gas.
A unit of measurement to describe a million barrels of curde oil, bitumen, natural gas liquids, or condensate.
A mixture of hydrocarbons and non-hydrocarbons (like Hydrogen Sulfide or Nitrogen) in the same gaseous space or in a mixture of crude oil in underground preserves
A compartment of the separator that gathers oil skimming over the oil weir.
The surface area, reservoir, wells and production equipment overlying oil reservoirs.
The pipe that directs oil out of the treater.
Similar to a dam, this vessel compartment allows oil to skim over into the oil chamber.
The party or person responsible for the drilling and operation of a well, and the maintenance of the leased land. All of the operator’s responsibilities will be detailed in the JOA.
An oil and gas lease that’s paid to the Lessor through the first term at the lease signing.
The part of the sucker rod pump that pulls well fluids into the pump.
Processing plant where crude oil is turned into a variety of more useful oils like gasoline and diesel.
The amount of oil and gas in a reservoir that can be extracted. Measured in terms of barrels of oil or million cubic feet (MCF)
The machine used to drive rotational power to the drill stem while still allowing vertical movement of the pipe for rotary drilling. Most moden rotary machines have a rotary or master brushing used to turn the kelly bushing, which then allows vertical movement of the kelly while the stem is turning.
A percentage of the profits made from the development of mineral resources. Royalties are paid to the property owners.
Funds given to the lessor from the production of oil and gas excluding production costs, taxes, and transportation fees.
Salt Water Disposal Well:
Oilfield salt water is drained into these wells.
Closing the valves on a well to stop production. Can also refer to a well on which the valves were closed to stop production.
Spring Loaded Back Pressure Regulator:
Controls the gas pressure and water level in the vessel of a free water knockout.
A pipe with a small diameter or a tube threaded at both ends. Tubing is lowered into a completed well so that oil and gas can be produced through the string of tubing.
A horizontal, vertical, or spherical vessel that separates well fluids into gas and total liquid. The oil leaves the vessel through the bottom, while gas leaves through the top.
The sector within the oil and gas industry that finds and produces crude oil and natural gas; often called the exploration sector.