Oil and Gas Terms Beginning with “D” — Page 5

A type of salt in which chromium atoms are in the plus-7 valence state, such as potassium dichromate, K2Cr2O7. Read more →

A material used in a capacitor to store a charge from an applied electrical field. A pure dielectric does not conduct electricity. Read more →

Dielectric permittivity is a measure of how strongly a material resists the establishment of an electric field within it, formally defined as the ratio of electric displacement to electric field strength, and in… Read more →

What Is a Dielectric Propagation Log? A dielectric propagation log is a wireline or LWD measurement that determines formation water saturation by measuring the dielectric permittivity and electromagnetic propagation… Read more →

Dielectric resistivity is the formation resistivity value derived by combining the two independent measurements — signal attenuation and phase shift — produced by a propagation resistivity tool as it transmits… Read more →

What Is Diesel Oil Mud? Diesel oil mud (DOM) is a non-aqueous drilling fluid in which diesel fuel (No. 2 fuel oil, a refined petroleum distillate) serves as the continuous phase base fluid, with emulsified water as the… Read more →

A difference map in seismic reservoir monitoring and 4D seismic analysis is a display created by subtracting one seismic amplitude or attribute volume from another acquired at a different time over the same subsurface… Read more →

The spontaneous potential (SP) measured between two electrodes placed close together in the borehole, as opposed to the normal SP, which is measured with one electrode in the borehole and one at surface. Read more →

Differential compaction is a sedimentary basin process that occurs after the deposition of sediments, where different parts of a sedimentary accumulation develop different degrees of porosity reduction or settle… Read more →

Differential pressure in petroleum engineering is the difference between two pressure measurements at specified locations in the well or production system, used as the primary driving force quantification for all fluid… Read more →

A differential spectrum in petroleum well logging and formation evaluation is a display or mathematical transformation that shows the rate of change of a measured log value with respect to depth or another variable —… Read more →

What Is Differential Sticking? Differential sticking occurs when a stationary drill pipe , drill collar , or bottomhole assembly (BHA) becomes embedded in the filter cake deposited on a permeable formation wall, held in… Read more →

Differential weathering correction is a seismic data processing step that removes the spatially variable time delay introduced by lateral changes in the thickness and seismic velocity of the near-surface weathering… Read more →

A differential temperature log is a wellbore measurement that records the rate of change of temperature with depth (dT/dz) rather than the absolute temperature at each depth point — by computing or directly measuring… Read more →

Pertaining to a cement that is not easily dispersed by a material known as a dispersant. This term is commonly abbreviated as DTD. Read more →

Pertaining to cement that is not easily dispersed by a material known as a dispersant when the slurry is mixed with water containing a high concentration of salt. The term is commonly abbreviated DTDS. Read more →

In seismic exploration, diffraction is the bending and scattering of seismic wave energy around the edges and tips of subsurface discontinuities and point scatterers, causing energy to propagate in directions that are… Read more →

Diffusion in petroleum engineering and reservoir physics refers to the spontaneous movement of molecules or ions from regions of high concentration to regions of low concentration under the driving force of a… Read more →

The diffusion equation in petroleum engineering — also known as the pressure diffusion equation or the pressure transient equation — is a partial differential equation that governs the propagation of pressure… Read more →

Diffusion relaxation in NMR (nuclear magnetic resonance) logging is the enhancement of the transverse (T2) relaxation rate of hydrogen nuclei in a fluid caused by the diffusive motion of molecules through an… Read more →

An intrusive rock that invades preexisting rocks, commonly in a tabular shape that cuts vertically or nearly vertically across preexisting layers. Dikes form from igneous and sedimentary rocks. Read more →

The increase in the volume of rocks as a result of deformation, such as when fractures develop. Read more →

Dilatancy theory in petroleum geomechanics and pore pressure prediction is the concept that certain rocks, particularly dense, well-cemented sedimentary rocks under high differential stress approaching their shear… Read more →

Rarefaction in seismic wave physics is the phase of a compressional (P-wave) or acoustic wave cycle in which the propagating disturbance causes the particles of the elastic medium to move apart from their equilibrium… Read more →

A diluent is a hydrocarbon liquid blended with heavy crude oil or bitumen to reduce viscosity to levels suitable for pipeline transportation, truck hauling, or upgrader feed, typically a light condensate, naphtha,… Read more →

The process of adding fresh mud (or liquid phase) in order to reduce the solids content and maintain the properties of the drilling fluid in the active system. Read more →

A dim spot in seismic exploration is an anomalously low-amplitude seismic reflection (relative to the background reflectivity of adjacent reflectors at the same depth) at a reservoir level, which results from the… Read more →

Dip in geology and petroleum engineering refers to the angle and direction at which a geological surface (a bedding plane, fault plane, formation top, or any other planar feature) inclines away from horizontal —… Read more →

Dip correction in well log interpretation and formation evaluation is the process of adjusting wireline and LWD log measurements to account for the angle between the wellbore axis and the true perpendicular to the… Read more →

A fault whose primary movement is in the dip direction. Dip faults are also referred to as dip-slip faults. Read more →