Oil and Gas Terms Beginning with “D” — Page 2

A decibel (dB) is a dimensionless unit that expresses the ratio between two quantities — power, intensity, pressure, or amplitude — on a logarithmic scale, named after Alexander Graham Bell and used throughout the oil… Read more →

A decollement (from the French "to unstick" or "to detach") is a near-horizontal or gently dipping fault surface along which a body of rock has been detached from the underlying rock and transported horizontally (often… Read more →

Deconvolution in pressure transient analysis is a mathematical operation that uses downhole flow-rate measurements (or surface flow-rate measurements when downhole rates are not available) to transform bottomhole… Read more →

The deep induction log (ILD) is the deepest-reading resistivity channel of a dual induction or array induction logging tool, employing a long transmitter-to-receiver coil array with additional focusing coils to measure… Read more →

Deep seismic sounding (DSS) is a seismic technique that uses very long source-receiver offsets (typically 100 to 500 kilometers or more), powerful energy sources (large explosive charges, arrays of vibrators, or airgun… Read more →

Deep tow in marine geophysics is a seismic acquisition method in which the seismic source (typically an air gun or sparker array) and/or the receiver (a hydrophone streamer or ocean bottom cable) are towed by a surface… Read more →

A deep penetrating charge (DPC) is a type of perforating shaped charge designed to maximize the depth of penetration of the perforation tunnel into the formation while accepting a smaller tunnel diameter compared to big… Read more →

A deep-water play is a petroleum exploration concept in which the productive reservoirs, traps, and hydrocarbon accumulations are located beneath water depths typically exceeding 300 meters (1,000 feet) — and often… Read more →

(noun) A production logging tool that uses a deflector plate or vane positioned in the flow stream within a wellbore to measure the velocity and direction of fluid flow. The force exerted on the deflector by the flowing… Read more →

A deflocculant (also called a dispersant or thinner) in drilling fluid engineering is a chemical additive that reduces or prevents the flocculation of suspended solids (particularly clay particles) in the drilling mud… Read more →

A deflocculated mud is a water-based drilling fluid treated with dispersant chemicals such as lignosulfonates, lignite, chrome-free thinners, or sodium acid pyrophosphate (SAPP) to break the attractive electrostatic… Read more →

The act of reducing the viscosity of a suspension by adding a thinning agent, also known as a deflocculant. Read more →

A defoamer (also called an antifoam agent) is a chemical additive incorporated into drilling fluids, completion fluids, produced water systems, and surface processing equipment to suppress or destroy foam that forms… Read more →

Defoaming plates are a set of closely spaced, inclined parallel plates or tubes installed inside an oil and gas separator to break the stable foam that forms when gas comes out of solution from the liquid. When foamy… Read more →

A degasser in drilling engineering is a mechanical device installed in the surface mud system that removes entrained gas — predominantly methane and other hydrocarbon gases that entered the drilling fluid from the… Read more →

What Is Degree API? Degree API (also written as °API or API gravity ) is the American Petroleum Institute's standardized scale for measuring the density of crude oil and petroleum liquids relative to water, measured at… Read more →

What Does Dehydrate Mean in Oil and Gas? To dehydrate in oil and gas processing means to remove water vapour from natural gas or liquid hydrocarbon streams to levels below which hydrate formation, corrosion, or pipeline… Read more →

Dehydration in oil and gas processing refers to the removal of water vapor from natural gas or associated gas to prevent hydrate formation, corrosion, and condensation in downstream pipelines and processing equipment,… Read more →

What Is a Dehydrator? Dehydrator (also called a gas dehydration unit or glycol dehydrator ) is a vessel or process system that removes water vapor from produced natural gas or liquid hydrocarbons to meet pipeline… Read more →

What Is a Delay Rental? Delay rental (also called a delay rental payment or annual rental) is a periodic payment — typically made annually — by an oil and gas lessee to the mineral rights owner (lessor) to maintain a… Read more →

What Is a Deliverability Test? Deliverability test (also called a back-pressure test or flow test) is a well evaluation procedure conducted on a gas well to determine its ability to produce against varying wellhead… Read more →

In geology, a delta is a low-lying sedimentary landform deposited where a river enters a standing body of water and loses transport energy, building characteristic lobe and fan architectures of delta plain, delta front,… Read more →

Delta rho (delta-rho, written as delta-rho or Drho) in well logging is the correction term applied to the compensated formation density log measurement to account for the effect of mudcake (the filter cake deposited on… Read more →

What Is Delta-T Stretch in Seismic Processing? Delta-t stretch (also written delta-T stretch or dT stretch) is a seismic processing artefact in which the application of normal moveout (NMO) correction to remove the… Read more →

What Is a Demulsifier? Demulsifier (also called an emulsion breaker or treating chemical) is a specialty chemical additive injected into produced crude oil or emulsion streams to break oil-water emulsions by… Read more →

A densimeter, also called a densitometer, is an instrument that measures the density or specific gravity of a fluid stream, which in oilfield service may be a gas, a liquid, or a multiphase mixture of gas, liquid, and… Read more →

A densitometer in petroleum engineering is an instrument that measures the density of a fluid — drilling mud, produced fluid, or process stream — either continuously in a flowing pipe (an inline or online densitometer)… Read more →

Density is mass per unit of volume, one of the most fundamental physical properties in the oil and gas industry because it governs how fluids behave in the wellbore, how rocks are characterized from logs, and how… Read more →

Density contrast is the spatial variation in mass per unit volume of rocks within the subsurface, expressed in kilograms per cubic metre (or grams per cubic centimetre) and typically reported as the absolute or… Read more →

Density measurement in the petroleum industry encompasses the determination of mass per unit volume for liquids, gases, solid rock, and fluid-rock mixtures across a range of contexts including wellsite drilling fluid… Read more →