Oilfield Terminology & Definitions.
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Drilling & Completions

Drilling and completions are core phases of oilfield development that transform a geological target into a functional well. The process includes well planning, bit selection, drilling, casing, cementing, and final preparation for hydrocarbon flow.

  • Conductor Casing
    19

    Conductor casing is the first, largest and shortest string of pipe in a well, set through loose surface ground to stop it caving, to give drilling returns a path to surface, and to carry early wellhead loads.

  • Mud Weight
    20

    Mud weight is the density of the drilling fluid, usually in pounds per gallon. It sets the hydrostatic pressure the mud column exerts on the formation and is the primary barrier against a kick.

  • Annulus
    22

    The annulus is the ring-shaped space between two concentric things in a well: drill pipe and open hole, tubing and casing, or one casing string and the next. Mud returns up it, cement fills it, and pressure in it is watched for the life of the well.

  • Spud
    25

    Spud is the moment drilling of a new well begins, when the bit first turns to make hole. The spud date is the reference point for regulatory reports, lease terms and every drilling performance metric.

  • Blowout Preventer
    78

    A Blowout Preventer (BOP) is a large, specialized valve or assembly of valves installed at the top of a wellbore during drilling and completions operations.…

  • Cementing
    55

    Cementing is the process of pumping a slurry of Portland cement and water (and often chemical additives) into the annular space between the steel casing…

  • Completion Fluid
    53

    Completion fluid is a specialized liquid used during the final phase of well construction—the completion phase—after drilling is finished and before production begins. Its primary…

  • Directional Drilling
    51

    Directional drilling is a specialized technique in the oil and gas industry where the wellbore is intentionally deviated from vertical to reach a specific subsurface…

  • Drill Bit
    48

    A drill bit is the cutting tool attached to the bottom of a drill string used to penetrate subsurface rock formations and create a borehole…

  • Drill String
    54

    A drill string is the entire column of tubular components that extends from the surface drilling equipment (such as the swivel or top drive) down…

  • Drilling Mud
    57

    Drilling mud, also known as drilling fluid, is a specialized fluid mixture used in rotary drilling operations to drill boreholes into the earth. It is…

  • Electric Submersible Pump
    86

    An Electric Submersible Pump (ESP) is a multistage centrifugal pumping system deployed downhole in an oil or water well to lift large volumes of fluid…