Oil and Gas Terms Beginning with “E” — Page 4

Erosion in petroleum production engineering is the progressive material loss and surface degradation of wellbore tubulars, valves, chokes, flow lines, separators, and pipeline fittings caused by the mechanical impact… Read more →

Erosion-corrosion is a combined material degradation mechanism in which the synergistic interaction of mechanical erosion (the removal of material from a metal surface by the impact of solid particles or fluid… Read more →

Erosion-corrosion is a combined material degradation mechanism in which the synergistic interaction of mechanical erosion (the removal of material from a metal surface by the impact of solid particles or fluid… Read more →

In oilfield measurement, logging, and survey applications, error refers to the difference between a measured or calculated value and the true value of the quantity being measured — encompassing systematic errors (biases… Read more →

An escape line on a drilling rig is a safety device — typically a wire rope, synthetic rope, or slide wire — installed from the elevated derrickman's working platform (the monkey board, approximately 27 to 30 metres… Read more →

What Is Estimated Ultimate Recovery? Estimated ultimate recovery (also called EUR or ultimate recovery ) is the total volume of hydrocarbons — oil, natural gas, or natural gas liquids — that a well, reservoir, or field… Read more →

A semi-enclosed coastal environment of deposition in which a river mouth permits freshwater to contact and mix with seawater. Read more →

Eustasy is the phenomenon of global (worldwide) changes in sea level, as distinct from relative sea level changes that affect only a particular region; while relative sea level at any given location on Earth is affected… Read more →

Global sea level, which changes in response to changes in the volume of ocean water and the volume of ocean basins. Read more →

An evaporation pit is an excavated surface impoundment dug to hold oilfield brine so that water leaves the system by natural evaporation, concentrating and ultimately stranding the dissolved salts and leaving a smaller… Read more →

What Is an Evaporite? Evaporite (also called evaporite deposit or chemical sedimentary rock ) is a sedimentary rock formed by the precipitation of dissolved minerals as saline water evaporates from a restricted marine… Read more →

In petroleum geophysics, an event is a coherent arrival of seismic energy recorded across multiple traces in a seismic dataset that represents a subsurface interface, reflector, or other geological boundary from which… Read more →

The excavation effect is a systematic error in neutron porosity log measurements that occurs in gas-bearing formations, where the presence of gas in the pore space causes the neutron tool to read an anomalously low… Read more →

Excess cement is the cement slurry remaining in the wellbore following a cement squeeze operation, where the original objective was to squeeze slurry into the perforations and behind the casing or liner to repair… Read more →

Exit velocity in perforating refers to the velocity of the metallic jet produced by a shaped explosive charge as it forms and penetrates casing, cement, and formation rock, reaching tip velocities of 6,000 to 10,000… Read more →

Expanding cement is a wellbore cement system formulated to undergo a small, controlled increase in bulk volume after it has set, so that the hardened cement sheath grows tight against both the casing on its inside and… Read more →

An expansion joint in oil and gas operations is a mechanical connection designed to accommodate relative axial movement (elongation or contraction) between two sections of pipe, tubing string, or structural element… Read more →

Expectation in petroleum engineering and geoscience refers to the expected value (statistical mean) of a probability-weighted outcome in reservoir characterization, reserve estimation, and investment decision analysis,… Read more →

An expendable gun in completion engineering is a perforating gun assembly designed to disintegrate upon detonation — the carrier components (the gun body, end caps, and structural elements that hold the shaped charges… Read more →

An expendable plug is a temporary stopper installed inside the completion pipe of a new oil or gas well so the crew can pressure-test the whole string before the well goes into service. With the plug sitting at a known… Read more →

An expert system in oil and gas is a rule-based artificial intelligence program that encodes domain-specific knowledge in an explicit IF-THEN-ELSE inference structure, using a knowledge base of facts and heuristics… Read more →

What Is Exploration? Exploration (also called upstream exploration or E&P exploration ) is the process of searching for, identifying, and evaluating potential oil and gas accumulations through geological mapping,… Read more →

(noun) A geologically defined concept comprising a specific combination of source rock, reservoir rock, seal, trap, and migration pathway in a particular area, which together create the conditions necessary for… Read more →

Surface seismic data acquired using an explosive energy source, such as dynamite. Read more →

(noun) A seismic acquisition geometry in which the distance between the source and the farthest receiver (offset) is increased beyond the standard spread length, providing longer-offset data that improves velocity… Read more →

Extensive dilatancy anisotropy, abbreviated EDA, is a rock-physics model and a form of azimuthal seismic anisotropy in which a rock mass is pervaded by stress-aligned, fluid-filled microcracks and fractures oriented… Read more →

An external cutter is a downhole fishing tool designed to sever stuck or lost pipe from the outside of the tubular — cutting through the outer diameter of drill pipe, casing, tubing, or drill collars at a selected depth… Read more →

The continuous phase of an emulsion. The internal phase is the dispersed droplets of emulsified fluid. Read more →

An external pulling tool is a downhole retrieval device run on slickline, braided line, or coiled tubing that latches onto the outside diameter of a fishing neck to recover temporary plugs, packers, gas-lift valves,… Read more →

What Is External Upset? External upset is a way of making the ends of an oilfield tubing joint a little fatter on the outside, right where two pipes are screwed together. The fatter wall gives the joint extra muscle so… Read more →