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 →

Drilling rate, more formally the rate of penetration or ROP, is the speed at which a drill bit breaks the rock beneath it and advances the wellbore, normally reported in feet per hour or metres per hour. It is the most… 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 →