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 →

A drillstem test (DST) is a well test conducted while the drill string is still in the hole, before the well is cased and completed. By packing off a zone of interest with inflatable packers or mechanically set packers… Read more →

A drillstring is the complete column of tubular components and tools that connects the rig's surface equipment to the drill bit at the bottom of the wellbore and transmits the rotation, weight, and drilling fluid needed… Read more →

In oilfield gas gathering, a drip is the accumulation of water and heavy hydrocarbon liquids that condense out of a flowing gas stream and collect at the low points of a flowline or pipeline, and by extension the term… Read more →

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

A drop ball is a precisely machined spherical object that is gravity-dropped or pump-circulated through wellbore tubulars to activate a downhole tool, sleeve, plug, or pressure-actuated mechanism by seating in a… Read more →

A drop bar (also called a sinker bar, go-devil, or bar) in wireline operations is a heavy, solid cylindrical weight made of steel or a dense alloy (typically 1-3/4 to 2-1/4 inch OD, 3-6 feet long, weighing 20-80 pounds)… Read more →

A drop sub (also called a dart sub, drop-in sub, or ball-drop sub) is a downhole tool that can be activated by dropping a ball, dart, or plug from the surface into the drill string or tubing string, allowing the dropped… Read more →

A drop-off gun is a type of perforating gun assembly designed to be released and left at the bottom of the wellbore after firing — the gun string falls to the bottom of the perforated interval or the rathole below the… Read more →

In exploration geophysics, dropout is the failure of a recording channel or a geophone to register a shot or a series of shots during a seismic survey, producing a gap in the data known as a dead trace. Every seismic… Read more →

A dry bed is a vessel packed with a granular solid desiccant through which natural gas is passed to strip out water vapour by adsorption, producing a gas dry enough to meet pipeline specification or to feed downstream… Read more →

Dry combustion is an in-situ combustion (ISC) enhanced oil recovery (EOR) technique in which only air, or oxygen-enriched air, is injected into a heavy-oil or bitumen reservoir to ignite and sustain a moving combustion… Read more →

Dry forward combustion is the fundamental variant of in-situ combustion (ISC) enhanced oil recovery in which only air or oxygen-enriched air (without water) is injected into the reservoir through an ignition well to… Read more →

Dry gas is natural gas composed predominantly of methane with little or no heavier hydrocarbons (ethane, propane, butane, and pentane-plus) that would condense into liquid at normal pipeline conditions. The distinction… Read more →

A dry hole is a wellbore that has not encountered hydrocarbons in economically producible quantities — a well that may contain traces of oil or gas shows, intervals of saline formation water, or nothing but… Read more →

Dry oil, also called clean oil, is treated crude that contains only small residual amounts of basic sediment and water, known throughout the industry as BS&W , and it is the finished product a producer is allowed to… Read more →

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

A dry-bed dehydrator (also called a solid desiccant dehydrator) is a gas processing device that removes water and water vapor from a natural gas stream using two or more beds of solid desiccant materials such as silica… Read more →

A dual completion (also called a dual-string completion, selective dual completion, or commingled dual completion) is a well completion configuration in which two separate reservoir zones or pay intervals are produced… Read more →

A dual induction log (DIL) is a wireline resistivity logging tool that measures the electrical resistivity of the formation surrounding the wellbore at two different radial depths of investigation simultaneously,… 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-permeability reservoir is a numerical representation of a naturally fractured formation in which fluid can flow to the wellbore through both the fracture network and the rock matrix, and in which the matrix… Read more →

What Is a Dual-Porosity Reservoir? Dual-porosity reservoir (also called a naturally fractured reservoir or double-porosity system ) is a reservoir containing two distinct and coupled pore systems: a primary matrix… Read more →

A dummy valve is a solid, ported-but-plugged or wholly blank gas-lift valve insert that is run into a side-pocket mandrel (SPM) on the production tubing string to mechanically isolate the tubing bore from the casing… Read more →

A dump bailer is a slim cylindrical wireline or slickline tool designed to carry a small, pre-measured volume of cement slurry, sand-laden gel, or similar setting material into a wellbore and release that material at a… Read more →

A duplex pump is a positive-displacement reciprocating pump with two cylinders (two pistons or plungers), each powered by a common crankshaft through connecting rods and crosshead assemblies, with each cylinder equipped… 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 →

A dynamic filter press is a laboratory instrument used in drilling fluid evaluation that measures the filtration rate and filter cake properties of drilling mud under simulated dynamic conditions — with the mud… Read more →

Dynamic filtration in drilling fluid engineering refers to the filtration of fluid through a permeable surface (the formation face or filter cake) while the fluid is in motion parallel to the filtration surface — in… Read more →