Oil and Gas Terms Beginning with “D” — Page 7

Distribution in oil and gas contexts refers most commonly to particle size distribution (PSD) — the statistical description of the range and frequency of particle sizes in a material sample, reported as the percentage… Read more →

Diurnal variation in geoscience refers to the cyclical change in a physical or environmental property of the Earth that completes one full cycle over approximately a 24-hour period corresponding to the Earth's rotation,… Read more →

In Cartesian coordinates, divergence is the sum of the partial derivatives of each component of the vector field with respect to the corresponding spatial coordinate: Read more →

Diversion in well stimulation and cementing refers to any technique used to force treatment fluids — acid, fracturing fluid, or cement slurry — into lower-permeability or lower-injectivity zones that would otherwise be… Read more →

What Is a Diverter Flowmeter? A diverter flowmeter is a production logging tool that measures the individual flow rates contributed by different producing zones in a cased wellbore by diverting the total wellbore flow… Read more →

What Is a Division Order? Division order is a legal document prepared by an oil company, pipeline purchaser, or first purchaser of production that identifies the fractional ownership interests of all parties entitled to… Read more →

A dog collar in oilfield usage is a steel safety clamp or temporary support device that is placed around the body of a tubular (drill pipe, casing, tubing, or drill collar) and set on the rotary table or slips to… Read more →

The dog house (also spelled doghouse) is the small enclosed shelter attached to the side of the rig floor or positioned immediately adjacent to the derrick on a drilling rig, serving as the primary workspace and refuge… Read more →

A dog leg is an abrupt turn, bend, or change of direction along a wellbore trajectory, a survey line, or a piece of drilling equipment, and the magnitude of that bend is the single most important variable a directional… Read more →

The dog house (also spelled doghouse) is the small enclosed shelter attached to the side of the rig floor or positioned immediately adjacent to the derrick on a drilling rig, serving as the primary workspace and refuge… Read more →

A dogleg refers to any abrupt change in direction of a wellbore, a survey line, or a piece of downhole equipment, and quantifying that change is one of the foundational tasks of every directional drilling operation in… Read more →

The name given to dolomitized limestone. Read more →

What Is Dolomitization? Dolomitization (also called dolomite replacement or dedolomitization reversal in some contexts) is the diagenetic process by which limestone — composed primarily of calcium carbonate (CaCO3) — is… Read more →

Dolostone (also called dolomite rock, though this name creates potential confusion with the dolomite mineral) is a carbonate sedimentary rock composed primarily of the mineral dolomite [CaMg(CO3)2] — a calcium-magnesium… Read more →

The set of values assigned to the independent variables of a function. Read more →

Domainal fabric is a rock texture or structural arrangement composed of multiple superposed spatial domains, each domain typically exhibiting different statistical properties (such as porosity, permeability, grain size,… Read more →

(noun) A geological feature in which a rock mass is divided into distinct structural domains, each with its own characteristic deformation style, fabric orientation, or strain pattern. In structural geology, domainal… Read more →

A type of anticline that is circular or elliptical rather than elongate. The upward migration of salt diapirs can form domes, called salt domes. Read more →

Slang term to describe a seismologist performing seismic field work. Read more →

To place lubricant on drillpipe, also known as "doping" the pipe. Read more →

A dosing pump (also called a metering pump or chemical injection pump) is a low-volume, positive-displacement pump with a precisely controllable and repeatable discharge rate used to inject chemical additives at… Read more →

Downdip is a directional descriptor in petroleum geology and reservoir engineering referring to the direction that lies farther down the slope of a dipping geological formation, stratigraphic surface, or structural… Read more →

What Is a Downhole Gauge? A downhole gauge is a small high-accuracy sensor that engineers send into the well to measure pressure and temperature at the depth of the reservoir. It records the readings on internal memory,… Read more →

A receiver located in a wellbore, as opposed to a location on the Earth's surface. Read more →

What Is a Downhole Safety Valve (DSV)? Downhole safety valve (DSV) (also called a subsurface safety valve or SSSV) is a fail-safe shut-off device installed in the production tubing string, typically 100 to 500 feet… Read more →

Downhole sensors are measurement devices deployed in the wellbore during drilling, completion, or production operations to collect real-time or time-stamped data on the physical conditions of the wellbore, the… Read more →

A seismic source located in a wellbore rather than at the Earth's surface. Read more →

Downlap is a stratigraphic and seismic-reflection geometry in which an inclined, more steeply dipping younger reflector terminates downdip against an older underlying surface that has a lower apparent dip, typically the… Read more →

What Is Downstream? Downstream (also called the downstream sector) is the segment of the oil and gas industry responsible for refining crude oil and natural gas liquids, processing and purifying natural gas, and… Read more →

A pipeline that receives natural gas or oil from another pipeline at some specific connection point Read more →