Oil and Gas Terms Beginning with “D” — Page 9

What Is a Drillship? A drillship is a ship-shaped mobile offshore drilling unit (MODU) equipped with a drilling derrick and a central through-hull opening called a moonpool, through which the drill string, marine riser,… Read more →

What Is a Drillstem Test? A drillstem test (DST) is a temporary well evaluation procedure performed with the casing string or open hole still in place, using a specialized downhole tool assembly to isolate a target… Read more →

The combination of the drillpipe, the bottomhole assembly and any other tools used to make the drill bit turn at the bottom of the wellbore. Read more →

The water and heavy hydrocarbons that condense from the gas stream and accumulate in the lower points of the flowlines. Read more →

A device used to collect water and heavy hydrocarbons that drop out of a gas stream in a pipeline. Read more →

A ball that is dropped or pumped through the wellbore tubulars to activate a downhole tool or device. When the ball is located on a landing seat, hydraulic pressure generally is applied to operate the tool mechanism. Read more →

A heavy steel bar that is dropped through the tubing or running string to fire the percussion detonator on a tubing-conveyed perforating (TCP) gun assembly. The drop bar must be capable of falling through the string… Read more →

A device, shaped like a short length of pipe, which is used to drop TCP guns in the rathole or sump. It is commonly used to drop guns that are connected to the completion into the sump, thus providing access to the… Read more →

A perforating gun assembly designed to be detached from the tubing or running string after firing. The detached assembly can then drop, or be pushed, to the bottom of the well depending on deviation and production… Read more →

The failure of a channel or geophone to record a shot or shots in a seismicsurvey, which results in a loss of data. Read more →

A hygroscopic solid such as silica gel, calcium chloride [CaCl2] or other materials used in dry-bed dehydrators to absorb water and water vapor from a gas stream. Read more →

An in situ combustion technique in which only air or oxygen-enriched air mixtures are injected into a formation. A drawback related to dry combustion is the highly corrosive and noxious combustion products that are… Read more →

A type of in situ combustion in which the burning front moves in the same direction as the injected air. As air is continuously supplied at the injection well, the fire ignited at this location moves toward the… Read more →

Gas produced from a well that produces little or no condensate or reservoir liquids. The production of liquids from gas wells complicates the design and operation of surface process facilities required to handle and… Read more →

A wellbore that has not encountered hydrocarbons in economically producible quantities. Most wells contain salt water in some zones. In addition, the wellbore usually encounters small amounts of crude oil and natural… Read more →

A treated oil that contains small amounts of basic sediments and water (BS&W). Dry oil is also called clean oil. Read more →

A subsurface rock that lacks contact with aquifers or meteoric water within the Earth. Read more →

A device that removes water and water vapor from a gas stream using two or more beds of solid desiccants, such as silica gel or calcium chloride [CaCl2]. Wet gas is passed through the solid material, which absorbs the… Read more →

A wellbore with simultaneous production of hydrocarbons, water or both from more than one producing zone. Although the term refers to cases in which only two separate zones are present, in actuality there may be… Read more →

The combination of a deep-induction and a medium-induction array on the same sonde. In a typical implementation, the two arrays share the same transmitters but have different receivers. If the dual-induction log is… Read more →

What Is the Dual-Water Model? The dual-water model is a petrophysical model for shaly sandstone reservoirs that accounts for the additional electrical conductivity contributed by clay minerals by treating the pore water… Read more →

A dual-porosityreservoir in which flow to the well occurs in both primary and secondary porosity systems. Read more →

A rock characterized by primary porosity from original deposition and secondary porosity from some other mechanism, and in which all flow to the well effectively occurs in one porosity system, and most of the fluid is… Read more →

A blank gas-lift valve placed in a gas-lift mandrel to isolate the tubing string from the annulus. Gas-lift valves frequently are replaced with dummy valves during intervention work on wells with gas-lift completions. Read more →

A wireline or slickline tool used to place small volumes of cementslurry, or similar material, in a wellbore. Typically, the slurry is placed on a plug or similar device that provides a stable platform for the… Read more →

A type of fluid pump, commonly used on workover rigs, that has two plungers or pistons. As a positive-reciprocating pump, the fluid flow rate is typically calculated from the number of strokes per minute that the pump… Read more →

(noun) An informal industry term for a dry hole — a well that fails to encounter commercially producible quantities of oil or gas and is subsequently plugged and abandoned. The term reflects the disappointment of… Read more →

A time-variant operation performed on seismic data. Normal moveout (NMO) is a dynamic correction. Read more →

Equipment used to measure filtration under dynamic conditions. Two commercial dynamic-filtration testers are available, one of which uses a thick-walled cylinder with rock-like characteristics as the filter medium to… Read more →

A filtration process in which the slurry being filtered is being circulated over the filter cake, so that the cake is simultaneously eroded and deposited. The erosion rate depends on the shear rate of the fluid at the… Read more →