Oil and Gas Terms Beginning with “E” — Page 2

Pertaining to a material that can undergo stress, deform, and then recover and return to its original shape after the stress ceases. Once stress exceeds the yield stress or elastic limit of a material, permanent… Read more →

A set of constants, also known as elastic moduli, that defines the properties of material that undergoes stress, deforms, and then recovers and returns to its original shape after the stress ceases. The elastic… Read more →

A temporary change in shape caused by applied stress. The change in shape is not permanent and the initial shape is completely recovered once the stress is removed. Read more →

The yield point, or the point at which a material can no longer deform elastically. When the elastic limit is exceeded by an applied stress, permanent deformation occurs. Read more →

A neutron interaction in which the kinetic energy lost by a neutron in a nuclear collision is transferred to the nucleus. The energy of a neutron is reduced more efficiently in collisions with nuclei of similar mass to… Read more →

A seismic or acousticwave, such as a P-wave. Read more →

A type of gas-lift valve that allows a gas-lift port size to be adjusted remotely from surface to positions from fully open to closed. Developed in the last 10 years, these valves offer the possibility of changing… Read more →

A small sensor in a productionlogging tool that distinguishes between hydrocarbon and water in its vicinity as it is moved up and down a production well. The electric probe was the first type of local probe to be… Read more →

An electric downhole pump used in heavy oil production that is designed with vane and fin configurations to accommodate frictional losses and pump efficiencies caused by heavy oil viscosity. Read more →

A difference in vertical and horizontal resistivity within a formation and at the scale of the resistivity measurement. Although there are several possible types of anisotropy, the term usually is used when the… Read more →

The ability of a material to support the flow of an electrical current. In linear isotropic materials, the electric current density at any point in space is proportional to the electric field; the constant of… Read more →

(noun) A corrosion monitoring device consisting of a metallic element exposed to the process environment, with electrical resistance measurements taken periodically to quantify metal loss due to corrosion. Unlike… Read more →

With reference to formation evaluation, the layer between a clay particle and the formation water that has a particular distribution of ions. Clays have an excess negative charge on their surface. When in contact with… Read more →

(noun) A downhole or inline sensor that measures the electrical impedance of a multiphase fluid mixture to determine the fraction of each phase (oil, water, gas) present at a specific point. The probe exploits the… Read more →

A wireline log of formationresistivity produced by a simple, unfocused arrangement of current emitting and measure electrodes. Conventional electrical devices have four electrodes-current emitting (A), current return… Read more →

The ability of a material to store a charge from an applied electrical field without conducting electricity. Read more →

An instrument used in a corrosion testing to determine metal loss. The probe directly measures the increase in resistance of a metal as its cross-sectional area is reduced by corrosion. At suitable times, once the… Read more →

The ability of a material to resist or inhibit the flow of an electrical current, measured in ohm-meters. Resistivity is the reciprocal of conductivity. Read more →

A test for oil-base and synthetic-base muds that indicates the emulsion and oil-wetting qualities of the sample. The test is performed by inserting the ES probe into a cup of 120°F [48.9°C] mud and pushing a test… Read more →

A particular combination of a spontaneous potential log and three electrical logs consisting of a 16-in. [40-cm] short normal, a 64-in. [162-cm] long normal and an 18-ft, 8-in. [5.7-m] lateral. With this combination, it… Read more →

A logging tool based on an arrangement of simple metallic electrodes working at low frequency (less than 500 Hz). The term includes conventional electrical logs, laterologs, micrologs and other microresistivity logs.… Read more →

The resistivity measured by an electrode device. The term often is used to distinguish this resistivity from that measured by the measurements-while-drilling propagation resistivity, or the wirelineinduction… Read more →

An electric motor that acts as a brake. Braking is accomplished by reversing the electric fields on the motor, effectively turning it into a generator. The usage of the generated power, either in useful applications or… Read more →

The electromagnetic force, in millivolts, generated by an electrolyte flowing through a permeable medium. This potential is an unwanted contribution to the spontaneous potential (SP) log. In principle, there is no flow… Read more →

An in-situ measurement of the inside diameter of a casing or tubing using an electromagnetic technique. As with the electromagnetic thickness measurement, and usually measured at the same time, a coil centered inside… Read more →

A process to increase thermal energy in a reservoir using electromagnetic means. The two types of electromagnetic heating are conductive and radio frequency (RF). In conductive heating, a current passes from one… Read more →

A group of techniques in which natural or artificially generated electric or magnetic fields are measured at the Earth's surface or in boreholes in order to map variations in the Earth's electrical properties… Read more →

Pertaining to logs that measure the properties of electromagnetic waves as they move through a formation. Measurements-while-drilling (MWD) propagation resistivity logs work between about 100 kHz and 10 MHz. Dielectric… Read more →

What Is Electromagnetic Propagation Measurement? Electromagnetic propagation measurement (EPM, also called the dielectric log or microwave propagation log) is a borehole logging technique that measures the propagation… Read more →

An in-situ measurement of the thickness of a casing or tubing string using an electromagnetic technique. The result is presented as a type of casing-inspection log, giving an estimate of metal loss and detecting… Read more →