Glossary

volt.

1. exploration and production. 2. those activities that include subsurface studies, seismic and geophysical activities, locating underground hydrocarbon deposits, drilling for hydrocarbon deposits and bringing hydrocarbons to the surface, well completion, and field processing of hydrocarbons prior to entering the pipeline. 3. the upstream end of the petroleum industry.

protrusions added to a traveling block to hold the elevators.

see pressure parting.

see Landsat.

a right that one individual or company has on the surface of another’s land. In the petroleum industry, it usually refers to the permission given by a landowner for a pipeline or access road to be laid across his or her property.

the movement of the tidal current away from the shore.

boiling, especially as applied to a system to remove heat from engine jacket water, wherein the water is permitted to boil and the evolved vapors are condensed in air-fin coolers.

a bit that does not have a uniformly round cross section; instead, the bit has a protuberance that projects from one side. An eccentric bit drills a hole slightly overgauge to compensate for certain formations, such as shale or salt, that deform and enlarge after being drilled. Eccentric bits can also ream undergauge holes.

a wire or chain fairlead where a wire or chain section does not pass through bearings, but where a sheave or wildcat is mounted eccentrically from the bearings.

equivalent circulating density.

economic out.

science of the relationships between organisms and their environment.

provision in gas purchase contracts that permits the purchaser to rescind contracts involving deregulated natural gas if prices of competitive fuels drop to the extent that distributors cannot compete in selling the gas.

federal agency that administers federal energy programs other than those regulated by the Federal Energy Regulatory Commission. See Department of Energy, Federal Energy Regulatory Commission.

a stage separator that saves liquid used in the refrigeration system, lets more surge tank liquid propane reach the chillers, and saves horsepower.

an electric current induced within the body of a conductor when the conductor either moves through a magnetic field or is in a region where a change occurs in the magnetic lines of force.

in the core of a transformer, losses in power caused by eddy currents in the core. Eddy current is induced in the core by the same magnetic lines of force (flux) that induce voltage in the windings.

a well on the outer fringes of a productive subsurface formation.

the water that touches the edge of the oil in the lower horizon of a formation.

see water drive.

a nozzlelike device that increases the velocity of a fluid. It is often used to mix two fluids or a fluid and solids.

European Economic Community.

extra, extra, extra improved plough (plow) steel.

extra, extra improved plough (plow) steel.

see electrically erasable programmable read-only memory.

the distance from the gauge point on the tank floor or datum plate to the top of the top angle or where the tank contents would begin to overflow.

a measure of the ability of a single fluid to flow through a rock when another fluid is also present in the pore spaces. Compare absolute permeability, relative permeability.

the percentage of the bulk volume of a rock sample that is composed of interconnected pore spaces that allow the passage of fluids through the sample. See porosity.

see RMS value.

the ratio of useful energy produced by an engine to the energy put into it.

in a hydrocyclone, the liquid that exits the cone through the vortex finder. Also called overflow.

any restriction imposed on quantities, discharge rates, and concentrations of pollutants that are discharged from point sources into U.S. waters, the waters of the contiguous zone, or the ocean.

water that is discharged from a refinery or petrochemical plant.

electronic flow measurement.

ethylene glycol.

see emergency escape unit.

emergency gas supply.

oxidation-reduction potential.

extremely hazardous substance.

Electronic Industries Alliance.

Energy Information Administration.

a tapered connection with 8 threads per inch (centimetre). One turn equals 0.125 inch (0.318 centimetre) of travel. A very common oilfield connection.

slang for a large truck-and-trailer unit that consists of a driver’s component (a cab or tractor) in which the engine is also located, and a cargo component (a trailer), which is attached to the tractor. Because in most tractor-trailer units the cab has ten wheels and the trailer has eight, the entire unit is called an eighteen wheeler.

extra improved plough (plow) steel.

environmental impact statement.

a nozzlelike device that increases the velocity of a fluid. It is often used to mix two fluids or a fluid and solids.

a collision between a neutron and the nucleus of an atom of an element such as hydrogen. In such a collision, the neutron’s energy is reduced by exactly the amount transferred to the nucleus with which it collided. The angle of collision and the relative mass of the nucleus determine energy loss.

temporary changes in dimensions caused by stress. The material returns to the original dimensions after removal of the stress.

the point at which a material permanently deforms when stressed.

see modulus of elasticity.

the capability of an object that is put under stress (e.g., is stretched) to recover its size and shape when the stress is released. Compare plasticity.

see modulus of elasticity.

a synthetic rubber made from polymers that has the elastic properties of natural rubber; packers (sealing elements) in blowout preventers and downhole packers are often made of elastomer. The term is formed by combining part of the word elastic and part of the word polymer-i.e., elast(ic) and poly(mer).

a fitting that allows two pipes to be joined at an angle of less than 180°, usually 90° or 45°.

electric log; used in drilling reports.

a decision taken to exercise or not to exercise an option to participate in the completion attempt on a well, including the costs of running completion production casing and all related completion costs. The decision is made when the operator is ready to run casing and complete the well and so ratifies the party owning the election.

see circuit.

see inductor.

see emulsion breaker.

see electric rig.

a machine by which mechanical energy is changed into electrical energy, such as an electric generator on a drilling rig in which a diesel engine (mechanical power) turns a generator to make electricity (electrical energy).

see conductor line.

see electric well log.

the process of running an electric log. See electric well log.

an electric device that converts electric energy to mechanical energy. Compare generator.

work that must be done against electric forces to bring a unit charge from a reference point to another point. It is also called electromotive force and voltage.

see relay.

a drilling rig on which the energy from the power source-usually several diesel engines-is changed to electricity by generators mounted on the engines. The electrical power is then distributed through electrical conductors to electric motors. The motors power the various rig components. Compare mechanical rig.

a device that uses a battery, an electric motor, gears, and cables to provide a way of starting an engine. An electrically actuated motor turns the engine over by means of a pinion gear in the starter that engages a ring gear on the engine flywheel.

see electric submersible pumping.

a form of artificial lift that utilizes an electric multistage centrifugal pump that is lowered to a depth in the well that submerges it into the liquids produced by the well. Electric power is conducted to the pump by a cable attached to the tubing.

see electric well log.

a record of certain electrical characteristics (such as resistivity and conductivity) of formations traversed by the borehole. It is made to identify the formations, determine the nature and amount of fluids they contain, and estimate their depth. Also called an electric log or electric survey.

see electric rig.

a circuit used to eliminate or reduce certain waves or frequencies while leaving others relatively unchanged.

1. a housing (box) into which electrical wires from two or more sources enter, join, and exit to other destinations. 2. a housing (box) mounted on an accumulator unit to provide an interface for remote electrical panels and an accumulator unit’s pod select valve, pilot valves, and various system pressures; normally two electrical junction boxes are provided in case one fails.

voltage.

see resistance.

a test for oil muds that determines the stability of the emulsion.

an integrated-circuit memory chip that has an internal switch to permit a user to erase the contents of the chip and write new contents into it by means of electrical signals.

a condition in an electrical circuit or component in which no electrical charge exists. The circuit or component is uncharged-that is, it has neither a positive nor a negative charge.

a hydraulic governor on an engine that has a reversible electric motor (it runs both clockwise and counterclockwise). By manipulating a remote control, the engine operator can adjust the electric motor to closely control the engine’s speed. See governor, hydraulic governor.

in a blowout preventer’s accumulator system, a reciprocating pump with three pistons that electric motors operate.

the rig crew member who maintains and repairs the electrical generation and distribution system on the rig.

the physical phenomena arising from the behavior of electrons and protons that is caused by the attraction of particles with opposite charges and the repulsion of particles with the same charge.

a transportation mode powered by electricity.

see galvanic cell.

see electromotive series.

see electrostatic treater.

a conductor of electric current as it leaves or enters a medium such as an electrolyte, a gas, or a vacuum.

an electrochemical process by which metal settles out of an electrolyte that contains the metal’s ions and is then deposited at the cathode of the cell.

a device mounted on the end of the drawworks shaft of a drilling rig. The electrodynamic brake (sometimes called a magnetic brake) serves as an auxiliary to the mechanical brake when pipe is lowered into a well. The braking effect in an electrodynamic brake is achieved by means of the interaction of electric currents with magnets, with other currents, or with themselves.

a quantity indicator for AC current or voltage.

the decomposition of a chemical compound brought about by the passage of an electrical current through the compound or through the solution containing the compound. Corroding action of stray currents is caused by electrolysis.

1. a chemical that, when dissolved in water, dissociates into positive and negative ions, thus increasing its electrical conductivity. See dissociation. 2. the electrically conductive solution that must be present for a corrosion cell to exist.

a capacitor that consists of two electrodes separated by an electrolyte. A dielectric film is formed on the surface of one electrode.

an instrument that uses the principle that moisture is absorbed on a phosphorous pentoxide film between two electrodes to measure the amount of water in a fluid such as gas.

the ability of a substance, usually in solution, to conduct an electric current.

to decompose by electrolysis.

a magnet consisting of a coil of conducting wire wound around a soft iron or steel core; the core is strongly magnetized when current flows through the coil, and is almost completely demagnetized when current flow ceases.

systems of collecting downhole data that use powerful electrically charged magnets. Using low-frequency electromagnetic wave propagation, the electromagnetic system facilitates highspeed data transmission to and from the surface through any formation. See electromagnetic wave propagation.

voltage created when a conductor cuts across, or is cut by, a magnetic field.

a special measurement while drilling (MWD) system that uses a low-frequency signal through the earth that is not affected by gas in the drill pipe. It uses equipment similar to conventional MWD tools to measure angle and direction, but an electromagnetic system also transmits signals to receivers on the surface.

device that emits microwaves into a formation and measures the way in which these microwaves are affected by the formation. By interpreting the effects, dielectric constants of fluids can be determined. Dielectric constants, in turn, can tell one whether fluid is water or hydrocarbons.

a system of producing electromagnetic waves to generate data on well holes. This is accomplished by attaching a wire to the wellhead, which makes contact with the drill pipe at the surface, and attaching another to a rod driven into the ground some distance away. The resulting differences in electromagnetic waves from the two test sites are then detected by the wires on the surface and decoded by computers.

magnetism produced by the action of a current flowing through a conductor. The electromagnetic field contracts and disappears when the current stops flowing.

refers to equipment comprising both mechanical and electrical components, such as electromechanical valves and electromechanical counters.

a device used to open or close electrical circuits (a relay) that is made up of mechanical parts that are actuated by electricity.

1. the force that drives electrons and thus produces an electric current. 2. the voltage or electric pressure that causes an electric current to flow along a conductor. 3. a difference of potential, or electrical, flow through a circuit against a resistance.

a list of elements arranged in order of activity (tendency to lose electrons). The following metals are so arranged: magnesium, beryllium, aluminum, zinc, chromium, iron, cadmium, nickel, tin, copper, silver, and gold. If two metals widely separated in the list (e.g., magnesium and iron) are placed in an electrolyte and connected by a metallic conductor, an electromotive force is produced. See corrosion.

a particle in an atom that has a negative charge. An atom contains the same number of electrons and protons (which have a positive charge). Electrons orbit the nucleus of the atom.

a pair of valence electrons that form a nonpolar bond between two neighboring atoms. See valance electron.

an almost obsolete electronic device in which electrons move through a vacuum or gaseous medium within an airtight glass (or other material) container. Also called radio tube; tube; vacuum tube; or, in Great Britain, valve.

the combining of atoms (the bonding) in which each atom of a bond pair contributes one electron to form a pair of electrons. Also called covalent bond. See electron pair.

the measurement of natural gas flow in a pipeline by the use of electronic devices, including computers.

an organization that writes, promulgates, and publishes Recommended Standards (RSs) for electronic and physical devices and their means of interfacing. For example, EIA-232 is a standard that defines a computer’s serial port, connector pins, and electrical signaling process. Address: 2500 Wilson Blvd., Arlington, VA 22201; 703-907-7500; www.eia.org.

a method of checking whether a device powered by electricity is operating correctly.

the exchange of data for business transactions by computer. Often used for nominations, dispatching, billing, and payment.

device to scan and analyze paper charts electronically. Greatly increases the number of charts that can be processed daily.

a meter that measures voltage directly, rather than in terms of its relation to current.

a vessel that receives an emulsion and resolves the emulsion to oil, water, and usually gas, by using heat, chemicals, and a high-voltage electric field. This field, produced by grids placed perpendicular to the flow of fluids in the treater, aids in breaking the emulsion. Also called an electrochemical treater. See emulsion treating.

the most common method of forming compounds, in which a positively charged ion and a negatively charged ion attract each other. Compare covalent reaction.

one of more than a hundred simple substances that consist of atoms of only one kind and that either singly or in combination make up all matter. For example, the simplest element is hydrogen, and one of the most abundant elements is carbon. Some elements, such as radium and uranium, are radioactive.

sulfur in its native or raw state; a pale yellow, odorless, and brittle material.

elevation; used in drilling reports.

to calibrate a device that measures liquid level by providing a zero starting point when the instrument reading is physically below the actual level.

a vessel above a datum line (usually ground level).

see elevator links.

cylindrical bars that support the elevators and attach them to the hook. Also called elevator bails.

on conventional rotary rigs and top-drive rigs, hinged steel devices with manual operating handles that crew members latch onto a tool joint (or a sub). Since the elevators are directly connected to the traveling block, or to the integrated traveling block in the top drive, when the driller raises or lowers the block or the top-drive unit, the drill pipe is also raised or lowered.

see separator.

a tank that has an elliptical cross section.

see stretch.

electromagnetic.

a blood clot obstruction of the pulmonary artery or a branch of the artery that leads to the lungs, causing sudden closure of the blood vessel.

1. Electromotive Division of General Motors Corporation. 2. a two-stroke-cycle diesel engine manufactured by the General Motors Corp.

a self-contained breathing apparatus that is used only for escape to a safe area. This self-contained breathing apparatus, when properly serviced, furnishes a 5- to 15-minute supply of breathing air. Emergency escape units may have masks or hoods. Also called egress unit. Compare work unit.

a bottled supply of gas for divers to use in emergencies.

a device run on drill pipe or tubing to recover the seal (the pack-off device) between the tubing and the tubing hanger in the wellhead. The recovery tool releases the tubing hanger’s lock-down ring, thus making it possible to retrieve the pack-off device.

see SARA Title Iii.

(under HAZWOPER) a response to an uncontrolled release of a hazardous substance that requires action by employees or other responders from outside the immediate release area. In other words, it is an emergency response if the release poses a potential safety or health hazard, and the release cannot be controlled by employees in the immediate area or by maintenance personnel.

a plan for emergency response situations that is available to employees and OSHA personnel for inspection and that contains (at a minimum) pre-emergency planning and coordination with outside parties; personnel roles, lines of authority, training, and communication; emergency recognition and prevention; safe distances and places of refuge; site security and control; evacuation routes and procedures; decontamination; emergency alerting and response procedures; critique of response and follow-up; and personal protective equipment (PPE) and emergency equipment.

electromotive force.

the right of a government (local, state, or federal) to take ownership of private property, which is to be used for the public’s benefit. Usually, the government entity compensates the private owner.

in a junction transistor, the region from which charge carriers that are minority carriers in the transistor’s base are injected into the base and control the current flowing through the transistor’s collector. Base and collector currents are combined in the emitter region and it serves as the outlet for total current in the transistor. See base (def. 2), collector.

see Hazard Communication Standard.

water so thoroughly combined with oil that special treating methods must be applied to separate it from the oil. Compare free water.

see emulsifying agent.

to convert into an emulsion.

a material that causes water and oil to form an emulsion. Water normally occurs separately from oil; if, however, an emulsifying agent is present, the water becomes dispersed in the oil as tiny droplets. Or, rarely, the oil may be dispersed in the water. In either case, the emulsion must be treated to separate the water and the oil.

a mixture in which one liquid, termed the dispersed phase, is uniformly distributed (usually as minute globules) in another liquid, called the continuous phase or dispersion medium. In an oil-in-water emulsion, the oil is the dispersed phase and the water the dispersion medium; in a water-in-oil emulsion, the reverse holds. A typical product of oilwells, water-oil emulsion is also used as a drilling fluid.

a system, chemical, device, or process used for breaking down an emulsion and producing two or more easily separated compounds (such as water and oil). Emulsion breakers may be (1) devices to heat the emulsion, thus achieving separation by lowering the viscosity of the emulsion and allowing the water to settle out; (2) chemical compounds, which destroy or weaken the film around each globule of water, thus uniting all the drops; (3) mechanical devices, such as settling tanks and wash tanks; or (4) electrostatic treaters, which use an electric field to cause coalescence of the water globules.

see oil-in-water emulsion mud.

a procedure carried out to determine the proportions of sediment and dispersed compounds, such as water, in an emulsion. Such tests may range from elaborate distillation conducted in laboratories to simple and expedient practices used in the field.

the process of breaking down emulsions to separate oil from water or other contaminants. Treating plants may use a single process or a combination of processes to effect demulsification, depending on what emulsion is being treated.

colloidal particles that take up water. See colloid.

equivalent mud weight.

electromagnetic measurement while drilling.

a collective term for a variety of petroleum-based derivatives such as asphalts, coal tars, grease and wax, mastics, and asphalt mastics that are used to coat pipe.

a chemical in drilling mud that surrounds (encapsulates) drilled solids.

an electronic device that converts decimal numbers to binary numbers. Compare decoder.

see water encroachment.

a claim or charge on property; for example, a mortgage or lien for unpaid taxes.

for automated lease operation, a sensor on field equipment to transmit status of operations, report data, or take action as needed.

one who actually consumes or burns a product, as opposed to the one who sells or resells it.

in data acquisition, a printout of data obtained from the start of a process to its completion.

a species that is in danger of extinction.

an act that declares the intentions of Congress to conserve threatened and endangered species and the ecosystems on which those species depend. ESA provides for federal designation of species determined to be endangered or threatened. It prohibits the taking of an endangered or threatened species of fish, wildlife, or vegetation.

the point marking the end of one stage of a process. In filtrate analysis, the endpoint is the point at which a particular result is achieved through titration.

the maximum stress that can be applied to a structure over the structure’s expected lifetime.

the capability of a body for doing work. Potential energy is this capability due to the position or state of the body. Kinetic energy is the capability due to the motion of the body.

a part of the Department of Energy (DOE) the main purpose of which is to disseminate information such as statistics to Congress, the administration, and the general public. Address: 1000 Independence Avenue SW; Washington, DC 20585; 202-586-2363.

a nonprofit, tax-exempt organization that aids the energy industry in dealing with technological advances by advising and educating members on new equipment and safety. Address: 5055 Royal Lane, Suite 116, Irving, TX, 75063; 888-503-8700; fax 972-915-6040.

a machine for converting the heat content of fuel into rotary motion that can be used to power other machines. Compare motor.

the cast steel or aluminum body into which the engine manufacturer bores and machines the cylinders; and onto and into which additional engine parts are installed.

a multi-bladed propeller usually installed behind an engine’s radiator, which moves air over an engine. It helps cool the engine and equalizes the temperature of the air as it flows over the engine, thus preventing hot spots. Engine power usually operates the fan, although some fans have auxiliary electric motors that power them when the engine is stopped.

coolant, such as water, that circulates through spaces in the engine block.

a device on an engine that senses overheating and shuts down the engine if overheating occurs.

see wait-and-weight method.

in offshore drilling, the examination and study of such factors as tensile loads, bending stresses, maximum operational water depth, buoyancy requirements, surface tension, and vessel response for the purpose of designing the best subsea marine riser and blowout prevention system.

a test that determines the volatility of a gasoline by measuring the percentage of the gasoline that can be distilled at various temperatures.

1. the introduction of artificial drive and displacement mechanisms into a reservoir to produce a portion of the oil unrecoverable by primary recovery methods. To restore formation pressure and fluid flow to a substantial portion of a reservoir, fluid or heat is introduced through injection wells located in rock that has fluid communication with production wells. See alkaline (caustic) flooding, gas injection, micellar-polymer flooding, primary recovery, secondary recovery, tertiary recovery, thermal recovery, water­flooding. 2. the use of certain recovery methods that not only restore formation pressure but also improve oil displacement or fluid flow in the reservoir. These methods may include chemical flooding, gas injection, and thermal recovery.

a process that goes beyond water or gas flooding and might involve steam, fire, chemicals, miscible gases, bacteria, or other techniques to recover oil and gas from wells. See enhanced oil recovery.

Energy Telecommunications and Electrical Association.

the heat content of fuel. A thermodynamic property, it is the sum of the internal energy of a body and the product of its pressure multiplied by its volume.

working-interest owner’s share of production. This volume may not equal actual sales because of contractual or market conditions.

drawn in and transported by the flow of a fluid.

formation gas that enters the drilling fluid in the annulus. See gas-cut mud.

liquid particles that may be carried out of the top of a distillation or absorber column with the vapors or residue gas.

water suspended in oil. Includes emulsions but does not include dissolved water.

1. the underground accumulation of oil and gas in geological traps. 2. the accumulation in rock pores of large polymer or surfactant molecules unable to move because of small exit openings. The coiled-up molecules reduce the permeability of pores to water but permit oil to pass through the pores.

a center for the collection and distribution of goods.

the internal energy of a substance that is attributed to the internal motion of the molecules. This energy is within the molecules and cannot be utilized for external work.

1. the sum of the physical, chemical, and biological factors that surround an organism. 2. the water, air, and land and the interrelationship that exists among and between water, air, and land and all living things. 3. as defined by the U.S. government, the navigable waters, the waters of the contiguous zone, the ocean waters, and any other surface water, groundwater, drinking water supply, land surface, subsurface strata, or ambient air within the United States.

laws enacted by the U.S. Congress that address protection of the environment.

see depositional environment.

a detailed environmental review document required under nepa.

conditions imposed on a vessel due to the effect of wind, waves, and current.

as defined in the Environmental Quality Improvement Act of 1970, a statement designed to “serve as an action-forcing device to ensure that the policies and goals of the act are infused into the ongoing policies of the government.” Its purpose is to “avoid or minimize adverse impacts” on the environment by providing the environmental analyses (used with other relevant materials) to make sound decisions regarding the environment.

enhanced oil recovery.

see extreme-pressure lubricant.

ethane-propane mix.

U.S. Environmental Protection Agency.

a number issued to any person, by site, whose act or process produces hazardous waste. Such a number is required by the EPA under the Resource Conservation and Liability Act of 1976 for the purpose of tracking hazardous waste.

Emergency Planning and Community Right-to-Know Act.

a shallow arm of the ocean that extends from the continental shelf deep into the interior of the continent. Also called epicontinental sea.

streams that last a short time.

the fundamental unit of time of the SI system of measurement, which is equal to 1/31,556,925.974  of a year.

see epeiric sea.

a neutron having an energy level of 0.02 to 100 electron volts.

a special neutron log used mainly in air- or gas-drilled holes to help determine formation porosity. An epithermal neutron log detects epithermal neutrons, which are neutrons released at energy levels higher than those released in normal neutron logging.

unit chemical weight of solute per million unit weights of solution. The epm of a solute in solution is equal to the ppm (parts per million) divided by the equivalent weight.

a division of geologic time; a subdivision of a geologic period.

1. any compound characterized by the presence of a reactive chemical structure that has an oxygen atom joined to each of two carbon atoms that are already bonded. 2. any of various resins capable of forming tight cross-linked polymer structures characterized by toughness, strong adhesion, and high corrosion and chemical resistance. Epoxys are used extensively as coatings and adhesives.

erasable programmable read-only memory.

1. a device used with mechanical drawworks brakes to ensure that, when the brakes are used, each brake band will receive an equal amount of tension and also that, in case one brake fails, the other will carry the load. A mechanical brake equalizer is a dead anchor attached to the drawworks frame in the form of a yoke attached to each brake band. Some drawworks are equipped with automatic equalizers. 2. any device used to distribute force equally on two pieces of equipment-for example, the pitmans on a beam pumping unit.

in crane operations, multiple-leg slings of wire rope and fittings that equally distribute the load among the slings.

in mathematics, a statement that each of two expressions is the same as (is equal to) the other. For example, a = b is an equation as is 2 + 5 = 3 + 4.

a mathematical expression that defines the physical state of a homogeneous substance by relating volume to pressure and absolute temperature for a given mass of the material.

the circumference of the horizontal great circle at the equator of a spherical tank. Compare great circle.

a state of balance between opposing forces or actions that is either static or dynamic.

see vapor-liquid equilibrium ratio.

the pressure at which a liquid and its vapor are in equilibrium at a given temperature.

those maxims and general principles that developed in England to moderate the common law and allow remedy for injury. In the broadest sense, justice.

a company owns part of a pipeline, but does not operate it.

the increase in bottomhole pressure expressed as an increase in pressure that occurs only when mud is being circulated. Because of friction in the annulus as the mud is pumped, bottomhole pressure is slightly, but significantly, higher than when the mud is not being pumped. ECD is calculated by dividing the annular pressure loss by 0.052, dividing that by true vertical depth, and adding the result to the mud weight. Also called circulating density, mud-weight equivalent.

a European term for the depth of liquid in a tank corresponding to a given ullage. It is obtained by subtracting the observed ullage from the height of the ullage reference point above the dip point on the bottom of the tank.

pressure expressed as the density of a mud that exerts that pressure. To determine it, the pressure gradient of the mud in use and a value for the constant that is required in the measuring system is used. In the English system, for example, the pressure gradient of a fluid that is 0.6344 pounds per square inch per foot (psi/ft) can be expressed as a mud density of 12.2 pounds per gallon (ppg). This density is derived from the equation P = MW x 0.052, where P is the pressure gradient in psi/ft and MW is mud weight in ppg. When solved for MW, the equation is MW = P ÷ 0.052. Thus, MW = 0.6344 psi/ft ÷ .052 = 12.2 ppg. 

a measurement of the hydrostatic pressure in the borehole when drilling is shut off, typically converted to an equivalent mud weight and referred to as the equivalent static density (ESD).

the atomic or formula weight of an element, compound, or ion divided by its valence. Elements entering into combination always do so in quantities proportional to their equivalent weights.

the unit chemical weight of solute per million unit weights of solution. The epm of a solute in solution is equal to the ppm (parts per million) divided by the equivalent weight.

Economic Regulatory Administration.

one of the major divisions of geologic time.

in a computer, a type of read-only memory (ROM) that can be erased and thus be reprogrammed for continuous use.

extended reach drilling.

the science of designing equipment for the workplace, wherein productivity is increased by reducing operator fatigue and discomfort. Also called biotechnology, human engineering, and human factors engineering.

the process by which material (such as rock or soil) is worn away or removed (as by wind or water).

the high-velocity ejection of a stream of drilling fluid from the nozzles of a jet bit to remove rock encountered during drilling. Sometimes sand or steel shot is added to the drilling fluid to increase its erosive capabilities.

the upper surface of the most recent sediment layer, formerly smooth and horizontal, modified by running water or other agents.

the closeness of the agreement between the results of successive measurements of the same quantity carried out by the same method, under the same environment, by the same observer, with the same measuring instruments, in the same laboratory, at quite short intervals.

a curve or graph that represents the error of a measuring device such as a pressure gauge as a function either of the quantity measured or of any other quantity that has an influence on the error.

Earth Resource Technology Satellite.

extended reach wells.

electric survey. See electric well log.

Endangered Species Act.

see tunnel diode.

on offshore drilling rigs and other offshore oil and gas facilities, a special lifeboat, which is usually suspended at deck level to provide easy entry for crewmembers, which is lowered by a single-line launch system, and which is self-propelled. Typically, escape capsules are not boat shaped; rather, they are disk shaped with watertight hatches on the top side of the capsule.

a cliff or relatively steep slope that separates level or gently sloping areas of land.

the reversion of property to the state in the event that the owner thereof dies without leaving a will (intestate) and has no heirs to whom the property may pass by lawful descent. Also called unclaimed property statute.

1. emergency shut down, an automated platform system to shut in an SCSSV and/or SSV. 2. equivalent static density.

electric submersible pump.

estimated; used in drilling reports.

the nature and extent of a person’s ownership or right or interest in land or other property.

an organic compound formed from the reaction between an organic acid and an alcohol.

estimated material remaining on board a vessel after a discharge. Includes residue or sediment clingage, which builds up on the interior surfaces of the vessel’s cargo compartments.

a calculation of the approximate amount of oil or that can be recovered from a reservoir during its productive lifetime.

a legal restraint on a person to prevent him or her from contradicting a previous statement.

a coastal indentation or bay into which a river empties and where fresh water mixes with seawater. Compare marine delta.

and others (Lat. et alii). Commonly used in oil and gas leases.

and wife (Lat. et uxor, and woman). Commonly used in oil and gas leases.

and husband (Lat. et vir, and man). Commonly used in oil and gas leases.

ethyl tertiary butyl ether.

a paraffin hydrocarbon, C2H6; under atmospheric conditions, a gas. One of the components of natural gas.

see monoethanolamine.

see ethylene.

a compound of ethanol and isobutylene. Compare methyl tertiary butyl ether.

a chemical compound of the olefin series with the formula C2H4. Official name is ethene.

a colorless liquid used as an antifreeze and as a dehydration medium in removing water from gas. See glycol, glycol dehydrator.

engine temperature switch.

European Union.

external upset end.

an organization established in 1958 by a treaty between Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany (now Germany). (It is informally known as the Common Market.) Aim of the EEC is to economically unify its member nations, with an ultimate goal of political union. EEC supports the free movement of labor and capital, the abolition of trusts and cartels, and the development of joint and reciprocal policies on labor, social welfare, agriculture, transport, and foreign trade.

established by the Treaty of Maastricht in 1993, an economic and political union of 27 member states located primarily in Europe. A standardized system of laws applies in all member states, and ensures the free movement of people, goods, services, and capital. It enacts legislation in justice and home affairs, and maintains common policies on trade, agriculture, fisheries and regional development. Sixteen member states have adopted a common currency, the euro.

two tubes that are actually empty spaces that run from the middle ear behind the eardrums down to the back of the throat.

the lowest temperature at which a liquid can exist.

1. to convert or change into a vapor. 2. to produce vapor. 3. to draw moisture from, as by heating, leaving only the dry solid portion. 4. to convert a liquid into vapor.

conversion of a liquid to a vapor or gas state.

a loss to the atmosphere of petroleum fractions through evaporation, usually while the fractions are in storage or in process. See vaporization.

a vessel used to convert a liquid into its vapor phase. A heat exchanger in which the medium being cooled gives up heat to the refrigerant through the exchanger transfer surface. The liquid refrigerant boils into a gas in the process of the heat absorption.

a sedimentary rock formed by precipitation of dissolved solids from water evaporating in enclosed basins. Examples are gypsum and salt.

on a ship or floating offshore drilling rig, the balance when the plane of flotation is parallel to the keel.

(pronounced tower) the shift of duty on a drilling rig that starts in the afternoon and runs through the evening. Sometimes called afternoon tour. Compare daylight tour, graveyard tour.

a term some regulatory agencies use to describe an occurrence in the oilfield that the agency does not consider normal or usual. For example, a kick (the entry of formation fluids into the wellbore) may be described as a well-control event by such agencies.

a thorough inspection of the recorded documents pertaining to a tract’s history of ownership. Title examinations are performed by attorneys who look for gaps in the chain of title, ambiguities, or any doubtful points that would cloud the present owner’s claim to the property. The examiner then sets forth in a written opinion the facts and instruments that, in his or her judgment, are necessary to make the title merchantable or legally defensible.

a fibrous material used as a filtering element in heaters or heater-treaters.

see butanes required.

the difference in the amount of gas between the producer’s deliverability capacity and the purchaser’s nominations.

a valve used automatically to prevent the liquid flow rate in a pipeline from exceeding a high limit.

gas purchased for lease use, surface or subsurface, when the amount the producer is entitled to is insufficient.

agreement between producers that provides for the exchange of gas produced from one property or interest for gas produced from another property or interest.

gas exchanged under provisions of an exchange agreement.

a piping arrangement that permits heat from one fluid to be transferred to another fluid as they travel counter currently to one another. In the heat exchanger of an emulsion-treating unit, heat from the outgoing clean oil is transferred to the incoming well fluid, cooling the oil and heating the well fluid. In the heat exchanger of a glycol dehydration unit, heat from the hot lean glycol flows through the inner flow tube in the opposite direction of the cool rich glycol, which flows through a shell built around the tube.

the increased energy condition of the nucleus of an atom after it has captured a neutron. On capture, the nucleus emits a high-energy gamma ray called a capture gamma ray.

a small DC generator mounted on top of a main generator to produce the field for the main generator.

the back electromotive force that flows through the primary winding of a transformer when no loads are connected to the secondary winding. See back electromotive force.

in computer science, an instruction that performs its operation on a bit-by-bit basis for its two operand words, usually storing the result in one of its operand locations. Also called XOR. See operand.

the completion of a legal instrument by the required actions-for example, by signing and delivering the instrument. Execution includes the actual delivery of the signed document to the named grantee, lessee, or assignee.

in regard to mineral rights and interests, the right to execute oil and gas leases. Executive rights may not include the right to bonus or rentals.

the person named in a will to carry out its provisions.

free or released from liability or requirement to which others are subject.

an interest owned in a property, usually by a charitable or a governmental agency, that is not subject to state production taxes as provided in the applicable tax regulations. Compare tax-free interest.

the burned gases that are removed from the cylinder of an engine. v: to remove the burned gases from the cylinder of an engine.

the mixture of gases that comes out of the cylinders of an internal combustion engine as a result of the ignition and burning of the fuel-air mixture in the cylinders. In underbalanced drilling with nitrogen as a circulating fluid, a diesel engine runs compressors and produces exhaust gas, which is high in nitrogen. The nitrogen is extracted from the exhaust gas and is used in the well. Because the nitrogen must be compressed to inject into the well, the cost of gas compression is shared with the cost of producing nitrogen, which makes both less expensive.

a piping arrangement, immediately adjacent to the engine, that collects burned gases from the engine and channels them to the exhaust pipe.

on an engine, flexible steel tubing that connects the engine exhaust manifold outlet to the muffler. See muffler.

an opening in a cylinder wall through which exhaust gas is expelled when the exhaust port is uncovered by the piston.

see muffler.

see tail pipe.

in an engine, the movement of the piston during which time it pushes burned fuel gases out of the cylinder.

valves (or ports), manifolds (passageways and connections), piping, noise silencers (mufflers), and other devices, such as exhaust stacks, that serve to remove burned fuel gases from an engine.

the cam-operated mechanism through which burned gases are ejected from an engine cylinder.

see rider.

a chemical reaction that releases heat.

see expandable tubular.

a special type of tubular, either casing or tubing, whose metal composition allows it’s inside diameter to be enlarged up to 20 percent after it is run into the well. Once the tubular is run into the well, an expansion tool is run into the tubular to the desired depth of the expansion and either hydraulic pressure or a mechanical tool enlarges the tubing’s diameter. The greatest benefit of expandable tubulars is increased production rates.

a siliceous volcanic rock that is finely ground and subjected to extreme heat. The resulting release of water leaves the rock particles considerably expanded and thus more porous. Expanded perlite is sometimes used in cement to increase its yield and decrease its density without an appreciable effect on its other properties.

a turbine through which a high-pressure gas is expanded to produce work. Used as a source of refrigeration in industrial processes such as the extraction of ethane, natural gas liquids (NGLs, the liquefication of gas, and other low-temperature processes). Also called a turboexpander.

the most commonly used cryogenic method of gas processing.

cement that expands as it sets to form a tighter fit around casing and formation.

see expansion factor.

the tendency of most materials to expand when heated and to contract when cooled.

see coefficient of expansion.

a cylindrical projection on top of a tank, tank car, or truck into which liquids may expand without overflowing. Gauge point is often in the expansion dome. Shell thickness is part of dome capacity.

a multiplying factor used when calculating gas flow rate. This factor corrects for the reduction in fluid density that a compressible fluid experiences when it passes through an orifice as a result of the increased fluid velocity and the decreased static pressure. Also called expansibility factor.

a device used to connect long lines of pipe to allow the pipe joints to expand or contract as the temperature rises or falls.

a loop built into a pipeline to allow for expansion and contraction of the line.

cooling obtained from the evaporation of a liquid refrigerant or the expansion of a gas.

a type of thermometer that uses a known cubical coefficient of expansion of a solid, a liquid, or a gas to provide indication in terms of degrees of temperature.

a device that converts the energy of a gas or vapor stream into mechanical work by expanding the gas or vapor through a turbine.

see coefficient of expansion.

a risk analysis process that multiplies expected gain or loss of a decision by its probability of occurrence and averages all possible outcomes to choose the action with the highest expected benefit.

a perforating gun that consists of a metal strip on which are mounted shaped charges in special capsules. After firing, nothing remains of the gun but debris. See gun-perforate.

a temporary plug set on a pressure-setting assembly and landed inside a production packer. The plug temporarily converts the packer into a bridge plug.

a perforating gun that consists of a hollow, cylindrical carrier into which are placed shaped charges. On detonation, debris created by the exploded charges falls into the carrier and is retrieved when the gun is pulled out of the hole; however, the gun cannot be reused. See gun-perforate.

deducted from income in the year in which the expenditure is incurred.

in insurance, the adjustment of the amount paid for insurance (premiums) resulting from the use of experience ratings. Experience rating plans are either retrospective plans or prospective plans. In retrospective plans, premiums are modified after the fact. That is, once the policy period ends, premiums are adjusted to reflect actual loss experience of the insured. Under prospective plans, an insured’s past experience (usually for the preceding 3 years) is used to determine the premium for the current year of coverage.

the development of a reservoir to extract its oil.

a well drilled to permit more effective extraction of oil from a reservoir. Sometimes called a development well.

the search for reservoirs of oil and gas, including aerial and geophysical surveys, geological studies, core testing, and drilling of wildcat wells.

A contract between the mineral owner of a tract of land under which petroleum deposits lie or are suspected to lie and a company, or companies, such as an oil company or companies, that agree to develop the prospect. The company may carry out surface geological studies, seismic exploration, and, eventually, drill exploration wells.

see E&P.

scientists who search for reservoirs of oil and gas and conduct geophysical surveys, geological studies, and core testing.

a plan required by the MMS before exploration can take place in the OCS. The plan must include measures to protect the environment. The MMS reviews the plan, analyzes the environmental effects, and determines any appropriate mitigating measures before approving the plan.

a well drilled either in search of an as-yet-undiscovered pool of oil or gas (a wildcat well) or to extend greatly the limits of a known pool. It involves a relatively high degree of risk. Exploratory wells may be classified as (1) wildcat, drilled in an unproven area; (2) field extension or step-out, drilled in an unproven area to extend the proved limits of a field; or (3) deep test, drilled within a field area but to unproven deeper zones.

one whose area of expertise is exploring for hydrocarbon deposits. Geologists and geophysicists may be explorationists.

drilling involved with the initial discovery of hydrocarbons. Also called wildcatting.

see exploration well.

an instrument used to measure the concentration of combustible gases in the air. Also called a gas sniffer.

see explosion door.

on an engine, one of usually several spring-loaded, lightweight metal plates placed over openings in the engine’s crankcase. Oxygen in the air entering the base of an engine mixes with the oil there. A hot spot could cause the oil and oxygen to explode and damage the crankcase. To prevent such damage, the spring-operated explosion covers (doors) open to release the pressure from the explosion. They then slam closed to prevent more air from entering. Also called explosion cover.

a motor with an enclosure designed to contain an internal explosion and to prevent ignition of surrounding gases or vapors by sparks that may occur in the motor.

when explosives are used to fracture a formation. At the moment of detonation, the explosion furnishes a source of high-pressure gas to force fluid into the formation. The rubble prevents fracture healing, making the use of proppants unnecessary. Compare hydraulic fracturing.

in mathematics, a number or symbol, such as the 3 in x3, placed to the right of and above another number, symbol, or expression, denoting the power to which that number, symbol, or expression is raised to. Also called power.

the limits (based on time of exposure, concentration of material, means of contact, and material toxicity) of worker exposure to hazardous materials without ill effect. Exceeding exposure limits set for various materials can result in temporary health problems, chronic illness, acute illness, or death.

the lease contains specific covenants, or obligations, for development. These replace implied covenants.

selected bentonites treated with chemical polymers. See extender.

a special bit nozzle, often used on large bits, that lengthens the nozzle and therefore places the jet of drilling fluid exiting the nozzle close to the bottom of the hole. With large bits, where regular nozzles can be relatively distant from the bottom of the hole, the cleaning power of the jet of drilling fluid may be lost because the velocity, or speed, of the jet diminishes rapidly after it exits the nozzle. By extending the length of the nozzles, the jets are placed closer to bottom for maximum cleaning.

the process of drilling a wellbore in which the final measured depth is greater than twice the vertical depth. See extended-reach wells.

a directionally drilled well that has a high degree of deflection.

1. a substance added to drilling mud to increase viscosity without adding clay or other thickening material. 2. an additive that assists in getting greater yield from a sack of cement. The extender acts by requiring more water than required by neat cement.

a tubular component attached to the bottom of a packer to extend its bore.

see crosshead extension rod.

a device made up on an overshot to lengthen it so that it can pass over the damaged top of a fish and securely engage an undamaged area of the fish. See overshot.

a fishing tool containing metal-cutting knives that is lowered into the hole and over the outside of a length of pipe to cut it. The severed part of the pipe can then be brought to the surface. Also called an outside cutter. Compare internal cutter.

a clamp used on the outside of pipe to align two lengths of pipe. External line-up clamps are usually used on pipe with a diameter of 8 inches (20 centimetres) or less. Compare internal line-up clamp.

see continuous phase.

on tubing, casing, or drill pipe, the thickening at each end of the joint such that the internal diameter of the joint is not affected; i.e., it remains uniform throughout the joint’s length. Only the outside diameter is enlarged at each end. Pipe is thickened, or upset, at each end to increase its strength so that threads, couplings, or tool joints may be attached. Compare internal-external upset end, internal upset end.

a device that is operated by a power source other than the fluid being sampled; for example, an electric or pneumatic motor.

used in wire rope construction definitions. It is a strong, tough, durable steel that combines great strength with high resistance to fatigue.

slips for drill pipe that fit into the tapered insert bowl of a four-pin master bushing and whose taper length is 12I inches (324 millimetres) long. Compare long rotary slips. See also master bushing, slips.

used in wire rope construction definitions. It is a grade used where a high breaking strength is required. This grade typically provides a breaking strength a minimum of 10 percent higher than EIPS.

it is a very high strength steel that provides a breaking strength 35 percent higher than EIP steel.

the substance that is to be separated from the raffinate.

the process of separating one material from another by means of a solvent. The term can be applied to absorption, liquid-liquid extraction, or any other process using a solvent.

the reduction in volume of wet natural gas due to the removal of natural gas liquids, hydrogen sulfide, carbon dioxide, water vapor, and other impurities from the natural gas stream. See shrinkage.

a plant equipped to remove liquid constituents from casinghead gas or wet gas.

in automatic sampling, a device for removing small amounts of liquid from a flowing stream and diverting these to a storage container.

a cyclone that develops in the middle and upper latitudes.

additives that, when added to drilling fluid, lubricate bearing surfaces subjected to extreme pressure.

1. chemical determined by the EPA to be extremely hazardous to a community during an emergency spill or release as a result of its toxicity and physical or chemical properties. 2. (under SARA) a substance listed in appendixes A and B of 40 CFR 355.

1. the emission of magma (as lava) at the earth’s surface. 2. the body of igneous rock produced by the process of extrusion.

volcanic; derived from magnetic materials poured out on the earth’s surface, as distinct from intrusive rocks formed from magma that has cooled and solidified beneath the surface.

igneous rock formed from lava poured out on the earth’s surface.

a loop, with or without a thimble, formed at the end of a wire rope. Also called an eye. See thimble.