Oilfield Glossary

A to C

Acidize - treat oil-bearing limestone or other formations with acid to increase production.

Acoustic (sonic) well logging - recording the time required for sound to travel a specific distance through rock, using a wireline of LWD instrument. The rate of travel varies with rock composition, porosity, and fluid content.

Along hole depth (AHD) - the distance along the path of the wellbore from a measured depth datum (e.g., the drilling rig floor) to a point in the well.

American Petroleum Institute (API) - an oil industry organization that is the leading standard-setting body for oilfield equipment and products.

Anisotropy - variation of a physical property depending on the direction in which it is measured. In geophysics, a difference between velocity parallel to the bedding plane and velocity perpendicular to the bedding plane for a lithologic unit. In geology, anisotropy usually refers to the differency between vertical and horizontal permeability.

Annulus - in a borehole, the space between the drill pipe and the borehole, between tubing and casing, or between casing and formation.

AutoTrak^® RCLS - a rotary steerable drilling system that combines an automated downhole guidance system, formation evaluation sensors, advanced drill bits and two-way communication with the surface to deliver high performance drilling and precise geosteering.

Barefoot completion - (also open-hole completion) a method of preparing a well for production in which no casing or liner is set opposite the producing formation.

Bit whirl - the motion a bit makes when it does not rotate about its center, but in a spiral motion. Usually occurring in soft formations, it results in an over gauge (bigger than the bit) hole and excessive bit wear.

Barrel (bbl) - 42 U.S. gallons

Bird - a device with moveable vanes attached to a marine seismic streamer to maintain the streamer at a predetermined depth.

Bull plug - a threaded, cylindrical device with a rounded closed end, used to seal off the casing string or instrument barrel to ensure pressure integrity.

Cake - compacted solid or semisolid material remaining after liquid/solid separation processes.

Casing - a borehole lining (pipe) separating the formation from the borehole, with or without cement between pipe and formation.

Casing hanger - in a well, a circular device with a frictional gripping arrangement of slips and packing rings used to suspend casing from a casinghead.

Casinghead - a flanged steel fitting connected to the first string of casing. It allows suspension of intermediate and production strings of casing and is the means for sealing off the annulus.

Cement -a powder consisting of alumina, silica, lime and other substances. It hardens when mixed with water and is used to bond casing to the walls of the borehole and to prevent fluids from migrating between permeable zones.

Centrifuge - a machine that uses centrifugal force to separate substances of varying densities.

Chemical inhibitor - liquid chemical compounds injected into lines carrying fluids that contain H₂S. Most inhibitors coat surfaces to isolate them from corrosive substances. Some react to produce less-destructive compounds.

Choke - a device to restrict the flow of fluids in a pipe.

Christmas tree - control valves, gauges, and chokes at the surface to control oil and gas flow in a completed well.

Closed Chamber Testing - a technique applied to drillstem testing.  Closed chamber testing provides data security and secrecy (minimal or no flare), and can measure minute quantities with exacting accuracy. Learn More.

CMP - Common midpoint - the assumption that a recorded seismic trace was reflected by a point midway (horizontally) between the source and detector.

Coiled Tubing - long sections of small-diameter tubulars deployed in rolls and used to replace jointed pipe in stimulation, workover and drilling operations.
Coiled Tubing/INTEQ; Coiled Tubing/Baker Oil Tools

The CoilTrak^® System - With the CoilTrak System, INTEQ has redefined the drilling and evaluation process for Coiled Tubing Drilling applications. CoilTrak combines the best LWD resistivity and PressTEQ^® services with either our latest CT Orienter or a Closed-Loop Rib Steering system — ensuring the ultimate in performance, well placement and system reliability on each well.

Collar - a device used to join two lengths of pipe.

Completion - technology used to bring a well to production. Matched to the reservoir and formation for optimum production, completion technology includes perforating, gravel packing, packers, safety valves, flow control, and completion fluids and services.

Conventional production logging - wireline well logs run in vertical production wells for the purpose of determining the wellbore oil, water, and gas inflow. Conventional production logging sensors include center-sampling (center-of-the-borehole) measurements of temperature, pressure, spinner velocity, fluid capacitance, differential pressure, and nuclear fluid density coupled to gamma ray, casing collar locator, and caliper measurements.

Coring Services - Coring is the removal of sample formation material from a wellbore. To the extent possible, core samples are taken in an undamaged, physically unaltered state. The formation material may be solid rock, friable rock, conglomerates, unconsolidated sands, coal shales, gumbos, or clays. Coring can be conducted by various methods with a variety of tools.