Oil and Gas Terms Beginning with “E” — Page 3

What Is Elemental Capture Spectroscopy? Elemental capture spectroscopy (also called ECS logging , neutron-induced gamma ray spectroscopy, or geochemical logging) is a pulsed neutron logging measurement that bombards… Read more →

Elevation correction in geophysics refers to any compensating adjustment used to bring measurements to a common reference plane (datum) — required when measurements are made at different elevations relative to sea level… Read more →

An elevator in drilling rig operations is a hinged mechanical clamping device used to grip drillpipe or other drillstring components for lifting and lowering operations during pipe handling — the elevator consists of… Read more →

An embedded wavelet in seismic data processing refers to the seismic wavelet that is implicitly contained within (embedded in) the recorded seismic trace data, representing the combined effect of the source wavelet, the… Read more →

Embrittlement in petroleum engineering is the reduction in ductility and fracture toughness of metals, elastomers, or cement used in wellbore and surface facility construction — caused by hydrogen absorption (hydrogen… Read more →

Empirical, in the context of petroleum engineering, petrophysics, and geoscience, describes an equation, correlation, model, or relationship that was derived by fitting mathematical functions to measured data rather… Read more →

What Is an Emulsion in Oil and Gas Production? An emulsion in oil and gas production is a stable dispersion of one immiscible liquid within another — typically water droplets dispersed in oil (water-in-oil emulsion, or… Read more →

Emulsion flow is a multiphase-flow regime in which oil is the continuous phase and water is carried along as small, roughly homogeneously distributed droplets dispersed throughout that oil, often with a thin film of… Read more →

What Is an Emulsion Mud? Emulsion mud (also called emulsion drilling fluid or oil-emulsion mud) is a drilling fluid in which one immiscible liquid is dispersed as fine droplets within another liquid continuous phase.… Read more →

En echelon describes a set of parallel or subparallel, closely spaced, overlapping or step-like minor structural features in rock, such as faults, veins, and tension fractures, that are arranged obliquely to the overall… Read more →

Encapsulation in petroleum drilling engineering refers to the process of coating or surrounding a water-sensitive shale particle or drilled cutting with a hydrophobic polymer film that prevents water from the drilling… Read more →

An endfire array in acoustic wireline and logging-while-drilling (LWD) sonic tools is a configuration in which multiple receivers are arranged axially along the tool body with their principal direction of sensitivity… Read more →

In petroleum engineering and geoscience, endpoint refers to the relative permeability values at the extreme saturation limits of a porous medium, specifically the oil relative permeability at irreducible water… Read more →

Enhanced diffusion in petroleum engineering and reservoir physics refers to the accelerated transport of dissolved or suspended species through a porous medium at rates significantly greater than predicted by ordinary… Read more →

What Is Enhanced Oil Recovery? Enhanced oil recovery (also called EOR , tertiary recovery, or improved oil recovery) is a broad category of techniques applied to oil reservoirs after primary (pressure depletion) and… Read more →

Entrained gas in drilling operations refers to gas that has been mechanically incorporated into the drilling fluid as small bubbles suspended within the mud matrix — distinct from formation gas that has invaded the… Read more →

An entrance hole in perforating engineering is the hole created in the casing wall and cement sheath by a shaped charge jet when a perforating gun is detonated to establish communication between the wellbore and the… Read more →

What Are Environmental Corrections? Environmental corrections are the systematic adjustments applied to raw wireline log measurements to remove the effects of borehole, invasion, temperature, pressure, and surrounding… Read more →

Eolian is the geological term for sediments and rocks that were deposited by wind rather than by water, ice, or gravity. The word comes from Aeolus, the Greek god of the winds. Modern eolian environments include the… Read more →

Epithermal neutron porosity measurement is a nuclear well logging technique that counts neutrons slowed to epithermal energies (approximately 0.1 to 100 eV) before they are absorbed or thermalized, providing formation… Read more →

EPM is the abbreviation for equivalents-per-million, a chemistry concentration unit that expresses the chemical equivalent quantity of a dissolved species per million parts of solution by mass — calculated by dividing… Read more →

The equalizing loop is the high-pressure piping and valve assembly built around the stripping rams of a snubbing unit. Snubbing is the practice of running pipe into or out of a live well under pressure, used during well… Read more →

An equalizing valve is a high-pressure valve, generally of small diameter, located on a pressure-bypass conduit that runs between the two sides of an isolation valve or blowout preventer (BOP) ram set — providing the… Read more →

What Is an Equation of State? An equation of state (EOS) is a thermodynamic model that describes the relationship between pressure, volume, temperature, and composition for a fluid system — used in petroleum engineering… Read more →

A technique to map a potential field generated by stationary electrodes by moving an electrode around the survey area. Read more →

What Is Equivalent Circulating Density? Equivalent circulating density (also called ECD or dynamic mud density ) is the effective density of the drilling fluid in the annulus while the mud pumps are running, calculated… Read more →

Equivalent conductance (or equivalent conductivity), in the context of petroleum formation water analysis and petrophysics, is the electrical conductance of an electrolyte solution normalized to the concentration of the… Read more →

An equivalent sack (also written as equivalent sack weight or equivalent sack volume) is a unit of measurement used in oilfield cementing to normalize the quantity of any cementitious material or blend to the absolute… Read more →

What Is Equivalent Water Resistivity? Equivalent water resistivity (Rwe) is the resistivity of a hypothetical pure sodium chloride solution that would produce the same spontaneous potential response as the actual… Read more →

Equivalent weight (EW) is a fundamental concept in oilfield chemistry expressing the mass of a substance that will react with, replace, or is chemically equivalent to one mole of hydrogen ions (H+) in an acid-base… Read more →