Glossary of oilfield jargon

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Oilfield terminology refers to the jargon used by those working in fields within and related to the upstream segment of the petroleum industry. It includes words and phrases describing professions, equipment, and procedures specific to the industry. It may also include slang terms used by oilfield workers to describe the same.


  • Bell nipple: An enlarged pipe at the top of a casing string that serves as a funnel to guide drilling tools into the top of the well.
  • Big bear: A big bear is a hitch (see hitch) that lasts a minimum of 50 straight days.
  • Blowout: A sudden, uncontrolled release of underground pressure from the well.
  • Chainhand (also motorman): An experienced laborer capable of maintaining most parts of the rig. The chainhand is in charge of throwing the chain to make up or break down pipe stands during tripping pipe. They are also responsible for maintaining the motors on the drilling rig
  • Cold vent: An area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. Constitutes a biome supporting several endemic species. More commonly a "cold seep"
  • Core sample: A cylindrical section of a naturally occurring medium consistent enough to hold a layered structure. Most cores are obtained by drilling into the medium, for example, sediment or rock, with a hollow steel tube called a corer
  • CSG (coal seam gas) or CBM (coal bed methane): Methane that forms in the gaps between coal molecules.[1] (not to be confused with csg, an abbreviation for the well casing)
  • Derrickman: The third in command after the driller & assistant driller.
  • Drill string: A column, or string, of pipe that transmits drilling fluid (via the mud pumps) and torque (via the Kelly drive or top drive) to the drill bit.
  • Driller: The crew supervisor on a drilling rig, working under the toolpusher.
  • Elevator: A hinged mechanism that is closed around the drill pipe, or other drill string components, to facilitate lowering them into or lifting them out of the wellbore.
  • Fish: The remnants of a broken drill string, or any object that has been unintentionally dropped down the wellbore. Fishing is the act of using specialized tools to retrieve a fish.
  • Floorhand: Laborer responsible for the overall maintenance of the rig.
  • Frac job: Slang term for hydraulic fracturing, a process whereby an oil or gas well is stimulated by pumping special fluids into the reservoir, fracturing the formation.[2]
  • Free point: A common method which involves deploying a wireline to estimate the depth at which the drill string can get un-stuck during drilling. Free point tools are designed to measure torque and stretch in tubing, casings, and drill pipes and to provide accurate free pipe indication. The highest point at which the drill pipe is "free" or not stuck. The pipe is then separated and all the pipe that is not stuck is laid down. Fishing tools are then used to attempt to retrieve the stuck pipe.
  • Ginzel: Slang term for a worker of the lowest "rank", often a rookie with no oilfield experience whatsoever.
  • Hanger: Refers to several different tools. The casing hanger is the portion of a wellhead assembly which provides support for the casing string when it is lowered into the wellbore. The liner hanger is used to hang casing liners (casing strings that do not reach the surface) from the internal wall of a previous casing string. The instrument hanger is a downhole tool on which downhole gauges or instruments that are to be temporarily left in the wellbore are attached. The tubing hanger attaches to the topmost tubing joint in the wellhead to support the tubing string.
  • Hitch: Rig employees refer to their work period as a 'hitch.' A common hitch is 20 days on, followed by 10 days off. Typically, two crews will be on and each crew will spend one week working 7am-7pm and the following week 7pm-7am. Or, crews may do a full two weeks of 7am-7pm and then, upon returning after their 10 days off, will work the next two weeks 7pm-7am (the third rig crew being on their 10 days off). Some rigs may operate four crews; these crews typically work eight hours shifts.
  • Horner plot: A semi-log plot produced during pressure buildup analysis.[3]
  • Intelligent well: An oil or gas well equipped with monitoring equipment and completion components that allow for automatic or remote optimization of production.
  • Joint: A length of pipe.
  • Kick: An intrusion of pressurized gas into the wellbore that causes drilling fluid to be displaced. It can be the precursor to a blowout.
  • Kickoff: A planned deviation from vertical, executed at the bottom of the wellbore.
  • Kill: The act of stopping a well from flowing.
  • Moon pool: An air-filled chamber open to the water below.
  • Motorman: Responsible for maintaining all equipment on the rig to ensure smooth operation and minimal downtime.
  • Mud: Slang term for drilling fluid. A "mud man" is the drilling fluids technician responsible for formulating the mud, while a "mud logger" checks mud cuttings from the drill bit for traces of rock or oil and gas that provide a picture of conditions downhole.
  • Pay: A reservoir or portion of a reservoir containing hydrocarbons that can be economically produced, i.e. it is capable of "paying" an income. Also referred to as "pay sand" or the "pay zone".
  • Petroleum play(or "play"): A group of oil prospects that are controlled by the same set of geological circumstances.
  • Pig: A device inserted into a pipeline for cleaning purposes. The act of using a pig is called pigging.
  • Piston corers: Advanced piston corer, extended core barrel systemsTemplate:Needs clarification
  • Pressure core sampler: A tool designed to retrieve a sediment core sample from depth under pressure.[4]
  • Roughneck: A member of an oil rig rigfloor drilling crew.
  • Sidetrack: A planned deviation from a previously drilled section of the wellbore. (Sidetrack cement plug, whipstock, open hole sidetrack)
  • Subsalt: Refers to oil prospects that lie below a salt layer.[5]
  • Toolhand: Refers to a third party (down hole services provider) service representative or field service supervisor with "tools" to be run and operated in a well.
  • Toolpusher: The boss of a drilling rig, working under the drilling superintendent or the corporation the rig is contracted to.
  • Tour: A 'tower' refers to a worker's shift. A drilling crew typically works a 12-hour tour every day until they have finished their hitch.
  • Treater: The head supervisor on a hydraulic fracturing crew. Leads operations execution on location in conjunction with feedback from other supervisors, equipment operators, field engineers, and customers.
  • V door: An opening at the floor level on one side of the derrick. It is used to move in equipment and tools such as casing and drill pipe.[6]
  • Water Transfer: The act of moving water from one location to another either to support drilling and completion activity when a well is being made or to remove flowback and produced water after the well has been made and oil and gas begin flowing back.
  • Well logging: The practice of making a detailed record (well log) of the geologic formations penetrated by a borehole. Also known as borehole logging. Wireline logging is the practice of measuring formation properties using electrically powered instruments to infer properties and make decisions about drilling and production operations.
  • Worm: An inexperienced oilfield worker who is not yet a "hand".[citation needed]

See also[edit]


  1. ^ "Jargon Buster". BG Group. Retrieved 18 July 2010. 
  2. ^
  3. ^ "PRESSURE BUILDUP ANALYSIS - HORNER PLOT". Peteng Computing. Retrieved 18 July 2010. 
  4. ^
  5. ^ "Oilfield Glossary: Term 'subsalt'". Schlumberger. 2010. Retrieved 12 June 2010. 
  6. ^ Mor, Jason. "Oilfield Jargon". Jobs in the Oil Patch. Retrieved 5 November 2016. 

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