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

Referring to a log of the yields of different elements in the formation, as measured by capture gamma ray spectroscopy using a pulsed neutron generator. The log is a type of pulsed neutron spectroscopy log that uses… Read more →

Any compensating factor used to bring measurements to a common datum or reference plane. In gravity surveying, elevation corrections include the Bouguer and free-air corrections. Seismic data undergo a static correction… Read more →

A hinged mechanism that may be closed around drillpipe or other drillstring components to facilitate lowering them into the wellbore or lifting them out of the wellbore. In the closed position, the elevator arms are… Read more →

The shape of a wavelet produced by reflection of an actual wave train at one interface with a positive reflection coefficient. The embedded wavelet is useful for generating a convolutional model, or the convolution of… Read more →

The process whereby steel components become less resistant to breakage and generally much weaker in tensile strength. While embrittlement has many causes, in the oil field it is usually the result of exposure to gaseous… Read more →

Pertaining to analysis that includes equations or formulae that were derived purely from data analysis and were not derived from a theoretical basis. The majority of equations used in reservoir characterization and… 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 →

A multiphase-flow regime with oil as the continuous phase, in which water exists as small, approximately homogeneously distributed droplets. There may also be a thin film of water on the pipe wall. Read more →

A water-base drilling fluid that contains dispersed oil or synthetic hydrocarbon as an internal phase. Early emulsion muds used diesel or crude oil dispersed into alkaline water-base muds. Synthetic liquids are now… Read more →

Describing parallel or subparallel, closely-spaced, overlapping or step-like minor structural features in rock, such as faults and tension fractures, that are oblique to the overall structural trend. Read more →

In drilling fluid parlance, the absorption of a polymer film onto cuttings and wellbore walls to form a coat or barrier. The term is usually applied to shale encapsulation by long-chain, acrylamide-acrylate (PHPA)… Read more →

A particular arrangement of transmitters and receivers used in the electromagnetic propagation measurement in which the dipoles used as sensors are oriented along the axis of the tool. The orientation is combined with… Read more →

During a titration procedure in analytical chemistry, the point at which reagent addition should be immediately stopped and the volume of reagent recorded. The endpoint represents the end of a specific chemical… Read more →

A technique in nuclear magnetic resonance (NMR) logging based on a long echo spacing, specially chosen to enhance the diffusion of formation water. Echo spacings in standard NMR logs are too short to allow any… Read more →

An oil recovery enhancement method using sophisticated techniques that alter the original properties of oil. Once ranked as a third stage of oil recovery that was carried out after secondary recovery, the techniques… Read more →

The gas present in the fluids of a wellbore circulatory system. Many well-intervention operations are conducted with the well live or held on balance. Fluids circulated within the wellbore under these conditions are… Read more →

The hole created in the internal surface of the casing or liner by the perforating charge or bullet. The entrance hole should be clean, free from burrs and round to create an efficient flow path between the reservoir… Read more →

The adjustments that must be made to log measurements to bring them back to the standard conditions for which the tool has been characterized. Different measurements require different corrections. For example… Read more →

Pertaining to the environment of deposition of sediments by wind, such as the sand dunes in a desert. Because fine-grained sediments such as clays are removed easily from wind-blown deposits, eolian sandstones are… Read more →

A measurement based on the slowing down of neutrons between a source and one or more detectors that measure neutrons at the epithermal level, where their energy is above that of the surrounding matter, between… Read more →

Abbreviation for equivalents-per-million. This unit of concentration is determined by dividing the number of equivalents of a substance by the weight of the solution that contains the substance, expressing the result as… Read more →

The high-pressure piping and valves configured around the stripping rams of a snubbing unit. The equalizing loop enables the wellhead pressure to be applied on both sides of the rams when closed, a process required… Read more →

A high-pressure valve, generally of small diameter, located on a conduit that runs between the two sides of an isolation valve or blowout preventer ram set. The forces acting on isolation devices such as blowout… 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 →

The effective density exerted by a circulating fluid against the formation that takes into account the pressure drop in the annulus above the point being considered. The ECD is calculated as: d + P/0.052*D, where d is… Read more →

With reference to the conductivity of brines, the ionic conductivity provided by a unit ion concentration. The conductivity of the brine (Cw, in siemens per meter or S/m) is determined by the equivalent conductance, (B,… Read more →

The weight of any cementitious material or blend based on the absolute volume of the cement. The term is normally used to define a sack of cement blend in which part of the cement has been replaced, on an absolute… Read more →

The effective resistivity of the formation water or the mudfiltrate, as it affects the electrochemical potential. The electrochemical potential is the main source of the spontaneous potential log. The equivalent water… Read more →

The molecular weight of an element, molecule or ion divided by its valence (or valence change for a redox reaction). For example, the molecular weight of calcium hydroxide, or "slaked lime," [Ca(OH)2] is 72.10. Because… Read more →