Oil and Gas Terms Beginning with “D” — Page 8

The portion of movement of a downhole pump at which the rods are going down and the downhole pump is being filled with fluid. Read more →

Downward continuation in potential field geophysics is a mathematical processing operation applied to gravity or magnetic field data measured at the surface (or at a given elevation above the earth) that transforms the… Read more →

A drag bag is a well logging technique and the associated tool assembly in which a packer-type flowmeter (an inflatable or mechanical flow-isolation device that diverts all flowing wellbore fluid through the flowmeter… Read more →

What Is Drainage in Reservoir Engineering? Drainage is the displacement process in which the wetting phase saturation decreases within a porous medium — oil (non-wetting) displacing water (wetting phase) during… Read more →

What Is Drainage Area? Drainage area (also called the well drainage area or productive drainage area) is the portion of a reservoir that contributes hydrocarbons to a specific well during its productive life, bounded by… Read more →

Drainage volume is the total volume of reservoir rock from which a single producing well draws hydrocarbons during its productive life — it is the three-dimensional rock volume that the well effectively depletes,… Read more →

A drainhole in petroleum engineering refers to either a short horizontal or near-horizontal borehole (typically 30 to 300 meters in length) drilled laterally from a vertical or near-vertical wellbore into a producing… Read more →

A drape is a structural configuration in which sedimentary layers conform to the shape of a buried feature beneath them, producing what looks like a fold but actually forms through differential compaction,… Read more →

The difference in height between the static level and the dynamic level in a pumping well, expressed as hydrostatic fluid pressure. Read more →

What Is a Drawdown Test? Drawdown test (also called a flow test or producing pressure transient test) is a pressure transient well test in which a well is produced at a controlled, approximately constant rate after a… Read more →

What Are Drawworks? The drawworks hoists and lowers the drill string, casing strings, and completion equipment through a crown block and traveling block system by spooling and unspooling heavy steel wire rope on a… Read more →

Drift in oil and gas has two primary technical meanings that are distinctly different but both operationally important: in wellbore geometry, drift refers to the deviation of a wellbore from vertical (or from its… Read more →

What Is a Drill Collar? A drill collar provides the weight on bit (WOB) and compressive stiffness needed to keep the bottom hole assembly on trajectory by placing the heavy, thick-walled pipe section directly above the… Read more →

A drill-in fluid is a specially formulated drilling fluid designed specifically for drilling through productive reservoir intervals — a category distinct from standard drilling mud in that its formulation prioritizes… Read more →

Drill solids (also called drilled solids or formation solids) are the solid particles of formation rock — including sand grains, clay minerals, silt, carbonates, and other lithic fragments — that are generated by the… Read more →

Drill-in fluid classifications in drilling engineering distinguish between the major categories of reservoir-section drilling fluids by their base fluid, solids loading, and cleanup mechanism: water-based drill-in… Read more →

A drill-noise vertical seismic profile (drill-noise VSP, also called seismic-while-drilling VSP or SWD-VSP) is a specialized vertical seismic profile (VSP) acquisition technique that uses the natural seismic energy… Read more →

A drillable packer is a downhole isolation device set inside production casing or liner that creates a permanent pressure seal between two zones and that, when no longer needed, must be removed from the wellbore by… Read more →

The driller is the senior crew member on a drilling rig responsible for operating the drawworks, rotary table or top drive, and all associated well control equipment from the driller's console, monitoring real-time… Read more →

Driller's depth is the depth measurement of a well or features within the wellbore as determined by tracking drillpipe and other drillstring components during drilling — the foundational depth measurement in well… Read more →

What Is a Drilling Break? Drilling break (also called an ROP break or formation break ) is a sudden, often significant increase in the rate of penetration (ROP) observed at the drill floor as the drill bit transitions… Read more →

What Is a Drilling Contractor? Drilling contractor (also called a contract driller or rig contractor ) is a company that owns and operates drilling rigs and provides the associated crews, equipment, and technical… Read more →

A drilling crew is the team of personnel assigned to operate a drilling rig on a continuous shift basis — typically organized into day and night tours of eight or twelve hours — comprising the driller, assistant driller… Read more →

A drilling detergent is a surface-active chemical additive (surfactant) incorporated into water-based drilling fluid systems to reduce the interfacial tension between the water phase and oil or grease contaminants that… Read more →

What Is Drilling Fluid? Drilling fluid (commonly called drilling mud ) is the engineered circulating fluid that a rig crew pumps down the drill string , through the bit, and back up the annulus during drilling… Read more →

A drilling procedure is a documented, step-by-step operational instruction that specifies the sequence of actions, parameters, and checks required to safely and effectively execute a specific drilling task — ranging… Read more →

The speed at which the drill bit can break the rock under it and thus deepen the wellbore. This speed is usually reported in units of feet per hour or meters per hour. Read more →

A drilling riser in offshore oil and gas operations is the large-diameter pipe assembly that connects the subsea blowout preventer (BOP) stack on the seafloor to the rotary table on a floating drilling vessel (drillship… Read more →

Drillpipe is the primary tubular component of a rotary drilling string, consisting of seamless steel pipe manufactured in 30-foot (9.1-meter) range 2 joints or 45-foot (13.7-meter) range 3 joints with a relatively… Read more →

Drillpipe conveyed (DPC) refers to a method of running downhole tools, perforating guns, logging tools, or specialized equipment into a wellbore by attaching them to the bottom of the drill string and lowering them on… Read more →