Glossary

radius.

1. a small plug that is run through a flow line to clean the line or to test for obstructions. 2. any plug left unintentionally in a pipeline during construction (as in, a rabbit that ran into the pipe). 3. a metal device that is placed in the inner core barrel before coring. When all of the core has been removed from the core barrel, the rabbit, or core marker, falls out to indicate that the barrel is empty. v: to pull a plug (a rabbit) through a pipe or line to ensure that it is open and free of dents.

a groove for the balls in a ball bearing or for the rollers in a roller bearing.

in electricity, a tube or channel that holds, guides, and protects electric wires.

1. framework for supporting or containing a number of loose objects, such as pipe. See pipe rack. 2. a bar with teeth on one face for gearing with a pinion or worm gear. 3. a notched bar used as a ratchet. 4. the dive control panel or manifold. v: 1. to place on a rack. 2. to use as a rack.

1. to place pipe withdrawn from the hole on a pipe rack. 2. to stand pipe on the derrick floor when pulling it out of the hole. Also referred to as racking the pipe.

see rack-and-pinion gear.

a gear comprising a bar with teeth on one face that engages with a pinion (a small gear).

a small platform with fingerlike steel projections attached to the side of the mast on a well-servicing unit. When a string of sucker rods or tubing is pulled from a well, the top end of the rods or tubing is placed (racked) between the steel projections and held in a vertical position in the mast.

radioactive densitometer.

electronic equipment that transmits and receives high-frequency radio waves to detect, locate, and track distant objects. The word is coined from the phrase ra(dio) d(etecting) a(nd) r(anging).

the drilling of several holes in a single plane, all of which radiate from a common point.

the flow pattern of fluids flowing into a wellbore from the surrounding drainage area.

(pronounced “leed”) in an electronic component, a wire (a lead) that exits each end of the component and is arranged so that the leads are attached to the component in a radial manner to the end of the component. Compare axial lead.

on the telescopic joint of a marine riser system, a flexible, strong rubber ring between the joint’s inner and outer barrel that keeps mud in the inner barrel from entering the outer barrel.

on offshore installations with grated deck flooring, a section or panel of grating that is cut into annular segments to fit into circular or annular shaped areas. See grating.

the heat from a fire that travels in all directions.

to send out, or emit, energy-for example, heat or light-in the form of rays or waves.

1. energy that is emitted from a source in the form of rays or waves-for example, heat, light, or sound. 2. energy that is emitted in the form of particles by substances-for example, uranium and plutonium, whose atoms are not stable and spontaneously decaying.

see radioactivity well logging.

an arrangement of pipes that contains a circulating fluid and is used for heating an external object or cooling an internal substance by radiation.

on an engine, the tube or tubes through which engine coolant is circulated. These tubes bend back and forth several times so that the coolant will have plenty of surface to contact as it flows through them. Very thin metal plates (fins) are attached to the tube, which radiate heat in the coolant to the surrounding air.

on an engine, very thin metal plates that are attached to the radiator’s tubes. Because there are hundreds of these plates in contact with the surrounding air, they efficiently radiate heat from the coolant circulating through the tubes.

on an engine, one of usually two flexible, reinforced tubes that conduct coolant in or out of the engine to or from the radiator. One hose is at the top of the engine and conducts hot coolant to the radiator; the other is at the bottom of the engine and conducts cooled coolant from the radiator back into the engine.

on an engine radiator, the piping through which coolant travels, usually from top to bottom, through the radiator. Radiator tubes usually have fins attached to them, which radiate (give up) heat to the surrounding air.

two or more atoms behaving as a single chemical unit, i.e., as an atom, e.g., sulfate (SO4), phosphate (PO5), nitrate (NO4), in which an atom of sulfur (S) and four atoms of oxygen (O), or an atom of phosphorus (P) and five atoms of oxygen, or an atom of nitrogen (N) and four atoms of oxygen behave as though they were a single atom when they combine with another atom or atoms. Ammonium sulfate (NHSO4), for example, is a compound in which the sulfur and oxygen atoms behave as a single chemical unit when they combine with nitrogen and hydrogen (H).

a now defunct association that published manufacturing standards for electronic components. RMA evolved into the Electronic Industry Alliance (EIA). See Electronic Industry Alliance.

a surveying method using radio waves to measure a large area of land by establishing a base line from which a network of triangles is built up; in a series, each triangle has at least one side common with each adjacent triangle.

see electron tube.

of, caused by, or exhibiting radioactivity.

the spontaneous transformation of a radioactive atom into one or more different atoms or particles, resulting in a long-term transformation of the radioactive element into lighter, nonradioactive elements.

a densimeter that measures fluid density by sensing the decay of naturally occurring radioactive elements in the fluid.

an isotope of the element iodine, which is radioactive and which is sometimes used as a radioactive tracer.

a radioactive material (often carnotite) put into a well to allow observation of fluid or gas movements by means of a tracer survey.

the property possessed by some substances (such as radium, uranium, and thorium) of releasing alpha particles, beta particles, or gamma particles as the substance spontaneously disintegrates.

usually, a gamma ray curve, but could also refer to any logging curve obtained by radioactivity logging.

a record of the natural or induced radioactive characteristics of subsurface formations. Also called nuclear log. See radioactivity well logging.

the recording of the natural or induced radioactive characteristics of subsurface formations. A radioactivity log, also known as a radiation log or a nuclear log, normally consists of two recorded curves: a gamma ray curve and a neutron curve. Both help to determine the types of rocks in the formation and the types of fluids contained in the rocks.

see radiofax.

a high-frequency (HF) radio broadcast that transmits weather information to special receivers (radios) on board ships and offshore installations and rigs. The receivers are equipped with facsimile (fax) machines that print out text and graphics of the information. Also called HF FAX, radio facsimile, and weatherfax.

photographic record of corrosion damage obtained by transmitting X-rays or radioactive isotopes into production structures. It may also be used to produce a shadowgraph of a pipeline weld and reveal any flaws. Also called X-ray testing.

an element, or one of its variants, that exhibits radioactivity.

relating to the measurement of geologic time by means of the rate at which radioactive elements disintegrate.

a technique for measuring the age of an object or a sample of material by determining the ratio of the concentration of a radioisotope to that of a stable isotope in it.

a balloon-borne instrument used to measure pressure, temperature, and humidity above the earth’s surface.

1. in a circle, a straight line that extends from the center of the circle to its edge. 2. in a sphere, a straight line that extends from the center of the sphere to its surface.

the remaining mixture that is separated from the extract solution.

a high-pressure manifold for fuel injection systems of some engines.

1. a point on a railway system where goods are loaded, unloaded, or transferred to other transport. 2. The furthest point on a railroad under construction to which rails have been laid.

an undertaking initiated by the U.S. Federal Railroad Administration, which is a part of the Department of Transportation, in cooperation with tank car manufacturers and users, in which tank cars that carry petroleum, petroleum products, and other chemicals are examined and investigated to ensure that such cars meet minimum safety standards. One goal is to prevent tank cars from derailing, leaking, or otherwise failing in order to prevent hazardous wastes from polluting the environment.

on polycrystalline diamond compact (PDC) bits, the angle at which the studs, on which are mounted the PDC cutters, are placed in the bit’s head. If a stud has a rake angle of 90°, the stud is perpendicular to the plane of the bit’s head. In most cases, the studs are mounted with back rake angle. See back rake angle.

the closing and sealing component on a blowout preventer. One of three types-blind, pipe, or shear-may be installed in several preventers mounted in a stack on top of the wellbore. Blind rams, when closed, form a seal on a hole that has no drill pipe in it; pipe rams, when closed, seal around the pipe; shear rams cut through drill pipe and then form a seal. See blind ram, pipe ram, and shear ram.

see ram.

a blowout preventer that uses rams to seal off pressure on a hole that is with or without pipe. Also called a ram preventer. Compare annular blowout preventer. See blowout preventer, ram.

the housing on a ram blowout preventer inside of which the rams and ram operating parts move when the preventer is operated.

see ram bonnet.

the sealing device in a ram blowout preventer that is usually made of synthetic rubber. The packer is molded to the ram’s upper and lower steel antiextrusion plates.

see ram blowout preventer.

a type of chain connecting link (Ramnas Mfg.).

a device that varies a frequency at a constant rate and incorporates an oscillator that can be programmed to provide an output over a specified frequency range.

an error that varies in an unpredictable manner in absolute value and in algebraic sign when a large number of measurements of the same value of a quantity are made under effectively identical conditions.

electronic data stored in such a manner as to allow a user to access and program it, and then read from it, erase it, and reprogram it.

1. the name given to the east-west lines of the rectangular survey system. Compare township. 2. in oceanography, the difference in height between consecutive high and low tides. 3. the region between the limits within which a quantity is measured, received, or transmitted, expressed by stating the lower and upper range values.

a grouping of pipe lengths. API designation of range lengths is as follows: Range 1 Range 2 Range 3 Casing Drill pipe Tubing 18–22 ft 27–30 ft 38–45 ft (6.10–7.32 m) (8.53–9.75 m)

an east-west line of the rectangular survey system.

in sucker rod pumping, the difference between the polished rod peak load on the upstroke and the minimum load on the downstroke.

the maximum angle to which a ship or mobile offshore drilling rig may be inclined and still be returned to its original upright position.

the interval within which the true value is expected to lie with a stated degree of confidence.

the capability of a meter or flow-measuring device to operate between the minimum and maximum flow range within an acceptable tolerance. Generally expressed as the ratio of maximum flow to minimum flow.

in process control, the calibration of process measuring instruments between its lower range value (zero) and its upper range value (span).

a temperature scale with the zero point at absolute zero. On the Rankine scale, water freezes at 491.60° and boils at 671.69°. See absolute temperature scale, absolute zero temperature.

a mill used in fishing operations, before running the fishing tool, to reduce the size of the box or collar on the lost tool.

usually relating to contract provisions stating that the pipeline company will attempt to take the seller’s fair share with other producers in the same reservoir.

to rotate a tool in a series of short movements (like that of a ratchet wrench) to cause the tool to set. Some packers, for example, are set by ratcheting the tubing string in which the packer is made up.

a gyroscope that is not allowed to pivot freely and is held in position as it spins within the instrument barrel.

see counting rate meter.

a measure of the speed at which the bit drills into formations, usually expressed in feet (metres) per hour or minutes per foot (metre).

in finance, the ratio of money gained or lost (whether realized or unrealized) on an investment relative to the amount of money invested. Also known as return on investment (ROI), rate of profit or simply return.

rate (commonly given in rpm) at which an action resulting from applied forces causes or tends to cause two adjacent parts of a body to slide relative to each other in a direction parallel to their plane of contact.

in process control systems, the speed with which a controlled variable changes in value.

1. a hole in the rig floor, some 30 to 40 feet (9 to 12 metres) deep, which is lined with casing that projects above the floor, into which the kelly and the swivel are placed when hoisting operations are in progress. 2. a hole of a diameter smaller than the main hole and drilled in the bottom of the main hole. v: to reduce the size of the wellbore and drill ahead.

the addition of a length of drill pipe or tubing to the active string using the rathole instead of the mousehole, which is the more common connection. The length to be added is placed in the rathole, made up to the kelly, pulled out of the rathole, and made up into the string. Compare mousehole connection.

a small, usually truck-mounted rig, the purpose of which is to drill ratholes for regular drilling rigs that will be moved in later. A rathole rig may also drill the top part of the hole, the conductor hole, before the main rig arrives on location.

approval and confirmation of a contract or other legal instrument, usually by means of a second written instrument.

in emulsion treating, a test to determine the best ratio of chemical to emulsion.

unrefined crude oil.

see feed gas.

unprocessed gas or the inlet gas to a plant.

gasoline extracted from wet natural gas.

see raw mix liquids.

a mixture of natural gas liquids prior to fractionation. Also called raw make.

in an engine’s heat exchanger, water that circulates outside and around the tubes through which the engine’s coolant circulates. Raw water is untreated water that removes heat from the engine’s coolant. Offshore, raw water is often seawater. Since raw water does not contact engine parts, it usually does not require treatment.

energy in wave form rather than in particle form.

a trademarked abbreviation for rotating blowout preventer.

see resistance-capacitance circuit.

rotating control device.

Resource Conservation and Recovery Act.

see cyclonite.

in an alternating current circuit, the impedance of current flow caused by capacitive or inductive components.

the rates and mechanisms of chemical reactions for a large number of gas-phase chemical reactions.

the compounds formed as a result of a chemical reaction, such as the reaction of an acid with rock. They may be solids (in which case they are called precipitates), liquids, or gases.

as applied to drilling muds, those components in the mud that are affected by and react with other mud components.

unstable reactive, organic peroxide; also water reactive (as defined by the Code of Federal Regulations).

the part of a drilling mud that consists of microscopic particles that can react with the liquid. The main reactive solids in most drilling muds are clays. Also called the colloidal phase.

the value of the power in an electric circuit obtained by multiplying the effective value of the current in amperes, the effective value of the voltage in volts, and the sine of the angular phase difference between current and voltage.

the amount of water-absorbent material in the drilling fluid.

the tendency of the drill string to turn in a direction opposite that of the bit, a factor for which a driller must compensate when using a downhole motor.

a measure of one substance’s ability to chemically react with other substances.

a device for storing electronic data in permanent, or nonerasable, form-that is, the data cannot be accessed, rewritten, or altered by a user. It is usually a static electronic or magnetic device that allows rapid access to the data.

a device that displays numbers or symbols and incorporates electric or electronic features.

a device that indicates or registers the value measured by an instrument in practical units.

a substance used in preparing a product or measuring a component because of its chemical or biological activity.

the ratio of the density of a gas, under the observed conditions of temperature and pressure, to the density of dry air at the same temperature and pressure. The ideal gas specific gravity is the ratio of the molecular weight of the gaseous mixture to the molecular weight of air.

the component of apparent power that represents true work. Real power is expressed in watts and equals volt-amperes multiplied by the power factor.

to enlarge the wellbore by drilling it again with a special bit. Often a rathole is reamed or opened to the same size as the main wellbore. See rathole.

to enlarge the wellbore by drilling it again with a special bit. Often, a rathole is reamed or opened to the same size as the main wellbore.

a tool used in drilling to smooth the wall of a well, enlarge the hole to the specified size, help stabilize the bit, straighten the wellbore if kinks or doglegs are encountered, and drill directionally. See ream.

on a diamond bit, a flat­tened place above the bottomhole cutting surfaces whose purpose is to ream the hole above the bottom of the bit.

a process in which the driller rotates and moves the drill stem up and down in the wellbore while circulating drilling fluid to clear the hole of debris or to prevent the drill stem from getting stuck.

see mill.

on an offshore pedestal crane, the distance from the crane’s center of rotation to the end of the crane’s maximum rear extension; also called tail swing.

a part of a farmout agreement or other assignment that stipulates an obligation to reassign earned acreage back to the farmer or assignor before the farmee or assignee allows the lease to expire on the acreage.

the auxiliary equipment to a fractionator or other column that supplies heat to the column. The vessel in which glycol that has absorbed water from the stream of gas in the contactor is regenerated by heating to boil off the water.

to inhale previously exhaled air or gases.

recovered; used in drilling reports.

periodic record of drilling mud performance and characteristics over the course of the drilling project.

see measurement ticket.

electronic equipment used for receiving modulated radio waves and converting them into the original intelligence, such as into sounds or pictures, or converting to desired useful information as in a radar receiver.

in an induction logging tool, a device that puts out electrical voltage, which is induced in the coil by eddy currents in a formation. The eddy currents are created by a transmitter coil on the logging tool. The amount of voltage induced in the receiver coil depends on the conductivity of the formation.

in parallel electronic circuits, the equation RT = 1 which states that total resistance (RT) in the circuit is equal to 1 divided by the sum of 1 divided by the resistance of each resistor (R) in the circuit, which are indicated as R1, R2, R3, R4, and so on.

a type of compressor that has pistons moving back and forth in cylinders, suction valves, and discharge valves, i.e., a positive-displacement compressor. Reciprocating compressors are used extensively in the transmission of natural gas through pipelines.

a type of engine that has up-and-down (reciprocating) motion of pistons in cylinders. Also called piston engine or displacement engine.

back-and-forth or up-and-down movement, such as that of a piston in a cylinder.

a pump consisting of a piston that moves back and forth or up and down in a cylinder. The cylinder is equipped with inlet (suction) and outlet (discharge) valves. On the intake stroke, the suction valves are opened, and fluid is drawn into the cylinder. On the discharge stroke, the suction valves close, the discharge valves open, and fluid is forced out of the cylinder.

a back-and-forth or up-and-down movement (as the movement of a piston in an engine or pump).

a recirculating cement mixer, which provides a more homogeneous slurry than a recirculating cement mixer (RCM). See recirculating cement mixer.

a cement mixing system in which previously mixed slurry is recirculated and mixed with a partial slurry formed by forcing dry cement into a ring of water. The partial slurry and the recirculated slurry combine to form a more consistent and more homogeneous slurry.

a hat that allows the diver’s exhaled gas to return back to the surface through another hose in the umbilical, be scrubbed of CO2, and replenished with oxygen, stored, and reused.

a system in which undesirable high-boiling contaminants of a stream are separated from the desired lighter materials; a purifying still.

an Electronic Industries Alliance (EIA) standard that describes the requirements for the interface between data processing and data communications equipment. It is widely used to connect computers to peripheral devices.

after the initial completion of a well, the action and techniques of reentering the well and redoing or repairing the original completion to restore the well’s productivity.

increasing the ambient pressure on a diver for the primary purpose of treating decompression sickness.

see deck decompression chamber.

equipment used to evaporate moisture collected from feed gas and restore the original concentration of glycol.

the process of conducting a preliminary survey, or mapping, of an area that is usually done rapidly and at relatively low cost, prior to mapping in detail and with greater precision.

a cross section of the earth generated by computer from tapes that have recorded the sound vibrations reflected during seismic exploration. Expert interpretation of record sections can reveal possible traps for petroleum. Also called seismic section.

a strip, disk, or sheet on which the indications of the measuring instrument are marked by a pen in the form of a graph.

a cross section of the earth generated by computer from tapes that have recorded the sound vibrations reflected during seismic exploration. Expert interpretation can reveal what may be a trap for petroleum. Also called seismic section.

a device made up in a drill stem testing assembly that holds pressure and temperature recorders. See drill stem test.

1. the act by which a legal instrument is entered in a book of public record, usually in the county clerk’s office. Such recording amounts to legal notice to all persons of the rights of claims specified in the instrument. 2. any means of preserving signals, data, sounds, or other information for future reference or reproduction.

a device, driven by a clockwork mechanism, that provides a chronological record of gauge indications (e.g., by tracing values of pressure, vacuum, voltage) on a paper form.

a measuring instrument that records the value of the measured variable by marking or printing on a removable paper chart, tape, or other suitable recording material.

a quantity recorder that keeps a permanent record of given variables in an electrical circuit on a paper strip or circular chart.

the quantity of natural gas determined to be economically recoverable and available for delivery from a well or wells. Amount may be limited to a specific period of time.

gas-lift gas that has returned to the surface and is not reinjected into the gas-lift system; rather, it is transferred to a pipeline. Sometimes called spent gas-lift gas.

the injection of oil into a formation to stimulate production. This oil may be recovered in later production.

1. the total volume of hydrocarbons that has been or is anticipated to be produced from a well or field. 2. the first system in an oil absorption plant in which products are removed from inlet gas by a combination of refrigeration and oil absorption. Some unwanted methane remains. See rejection, separation.

the recoverable amount of original or residual hydrocarbons in place in a reservoir, expressed as a percentage of total hydrocarbons in place. Also called recovery factor.

see recovery efficiency.

the method of measuring land adopted by the United States in 1785. Under this system, land is measured in squares called congressional townships, which are approximately 6 miles (9.6 kilometres) wide and approximately 6 miles long. The squares are marked off by means of parallel north-south lines called township lines and parallel east-west lines called range lines.

the top section of the separation tower. Also called rectifying section.

an electrical device that converts alternating current into direct current.

a permanent magnet meter with a rectifier built in to convert AC to DC.

to change an alternating current to a direct current.

a fold of rock in which the axial plane of an overturned fold has become horizontal or nearly so.

returning part of a gas processing stream to a point upstream to enhance recovery or control.

see red-lime mud.

a water-base clay mud containing caustic soda and tannates to which lime has been added. Also called red mud.

a layer of sedimentary rock that is predominantly red, especially one of Permian or Triassic age.

natural gas delivered to a pipeline company either from a gathering system or from another pipeline company rather than to a distribution point. Compare delivery gas.

describes all chemical reactions in which atoms have their oxidation state changed.

see oxidation-reduction potential.

any chemical reaction that involves oxidation and reduction. In nonamine processes, H2S is directly converted to elemental sulfur and water by reacting with oxygen.

the amount of pressure generated on the drill stem when the mud pumps are run at a speed (or speeds) slower than the speed used when drilling ahead. An RCP or several RCPs are established for use when a kick is being circulated out of the hole.

a fitting that makes an angle between two joints of pipe and that decreases in diameter from one end to the other.

a flange fitting used to join pipes of different diameters.

a pipe fitting that is threaded on both ends and decreases in diameter from one end to the other.

a T-shaped pipe fitting with openings of two different sizes.

adding one or more electrons to an atom or ion or molecule.

any deliberate duplication or partial duplication of circuitry or information to decrease the probability of a system or communication failure. In the transmission of information, the fraction of the gross information content of a message which can be eliminated without loss of essential information.

a unit of viscosity measurement, expressed in seconds, obtained when using a Redwood viscometer. It is the standard of viscosity measurement in Great Britain.

1. a type of reservoir trap composed of rock (usually limestone) formed from the shells or skeletons of marine animals. 2. a buried coral or other reef from which hydrocarbons may be withdrawn. v: to pick up the platform from its existing location and move it to an approved area.

a revolving device (such as a flanged cylinder) for winding or unwinding something flexible (such as rope or wire).

a lay barge specially outfitted to lay pipe from an immense reel on deck. The pipe is connected and reeled onto the barge on shore. This is an efficient way to lay offshore pipelines of relatively small diameter, although improved techniques may make it possible to use pipe of up to 30 inches (76 centimetres) in diameter.

an offshore pipeline construction technique in which the welded, coated, and tested pipe is coiled onto a reel and transferred to a reel barge, where it is paid out at a steady rate onto the ocean floor.

see reel vessel.

necessitates pipe to be prefabricated in a linear onshore facility and then wound onto a reel. Any pipe deformation while being spooled onto the reel is removed during the laying process by passing the pipe through a straightening machine.

a ship or barge specially designed to handle pipeline that is wound onto a large reel. To lay the pipeline, the vessel pays out the pipe off the reel at a steady rate onto the ocean floor. The pipeline has been constructed at an onshore facility where it has been welded, coated, inspected, and wound onto the reel.

see coiled tubing.

to pass (as a rope) through a hole or an opening; to pass a rope over or through sheaves (pulleys) in a block.

to string a wire rope drilling line through the sheaves of the traveling and crown blocks to the hoisting drum.

a rope system where the rope travels around drums and sheaves.

to renew a faced surface by recutting or regrinding.

the circumference of the bottom ring of a tank measured by the manual tank strapping method.

the conditions of temperature and pressure to which measured volumes are to be corrected.

the distance from the reference point to the datum plate or the bottom of the tank. It should be stamped on the fixed benchmark plate or stenciled on the tank roof near the gauging hatch. Also called reference height.

engine fuel of known octane or cetane number used as a standard in the engine testing of fuels.

see reference depth.

a device calibrated to hold or deliver a known volume of liquid.

see gauge point.

to manufacture petroleum products from crude oil.

cost of crude oil to the refiner, including transportation and fees. The composite cost is the weighted average of domestic and imported crude oil costs.

the physical plant and attendant equipment used in the process of refining.

the gas produced from certain petroleum refinery operations (such as cracking or reforming). The composition of refinery gas varies in accordance with the process by which it is produced, but it consists essentially of the same paraffin hydrocarbons as natural gas plus olefins (propylene, butylene, and ethylene) not found in natural gas.

fractional distillation of petroleum products, usually followed by other processing such as cracking.

any chemical used in the refining process that speeds or alters the process without the catalyst’s being affected.

to redirect something that strikes a surface, especially light, sound, or heat usually back toward its point of origin.

in cases where a wave of energy encounters a surface, the ratio of the energy reflected from a surface to the energy that falls on the surface. For example, if light strikes a surface that has high reflectance, most of the light reflects from it; conversely, if the surface has low reflectance, very little of the light reflects from it.

the process of shortwave radiation’s being sent back from the earth into space in the form of long-wave radiation. The process occurs when shortwave radiation meets light-colored areas that lack absorptive qualities.

in a distillation process, that part of the condensed overhead stream that is returned to the fractionating column as a source of cooling. v: in distillation extraction of fluids from a core, to use a solvent to flow over a core sample a second time to clean it.

a length of tubing or pipe bent to assume a coiled shape and through which a fluid cooler than the fluid outside the coil is circulated. The cooler fluid is used to cool the warmer fluid. Cooling causes vapors to condense to liquid.

a device on which reflux condenses in the distillation process. See reflux.

a relative measurement of the volume of reflux in the distillation process. The ratio is commonly expressed as the quantity of reflux divided by the quantity of net overhead product.

to rewrite a contract, guided by principles of equity. Parties who believe, for example, that the written form of an oil and gas lease does not express what was in fact intended or agreed on may sue in hope that the court will agree with them and reform the lease to express the intended facts or circumstances.

a liquid mixture of hydrocarbons.

a cracking process in which low-octane naphthas or gasolines are converted into high-octane products. Thermal reforming is carried out at high temperatures and pressures (932°–1,040°F, 500°– 560°C, 250 to 1,000 pounds per square inch-1.7 megapascals). Catalytic reforming is carried out at lower temperatures (850°–950°F, 454°–510°C) and much lower pressures. Reforming is usually a once-through process.

a special gasoline blend that burns with less hydrocarbon and other pollutant emissions.

to alter the course of a wave of energy that passes into something from another medium, as water does to light entering it from the air.

deflection from a straight path undergone by a light ray or energy wave in passing from one medium to another in which the wave velocity is different, such as the bending of light rays when passing from air into water.

any of several heat-resisting materials, usually a ceramic.

fracturing a formation again. See acid fracture, formation fracturing, hydraulic fracturing.

a system that operates by continuous circulation of a refrigerant in a four-step cycle: expansion, evaporation, compression, and condensation.

see Rivers and Harbors Appropriations Act of 1899.

wet gas that has been heated in a regeneration gas heater to temperatures of 400°–460°F (204°–238°C) in a solid desiccant dehydration system. The gas is passed through a saturated adsorber tower to dry the solid desiccant in the tower and remove the previously adsorbed water.

a mercury removal system using silver deposited on the molecular sieve pellets. The silver reacts with the mercury producing an amalgam that is insoluble in hydrocarbon liquid.

treating used to remove large quantities of contaminants by chemical reaction (amine-based solvents or nonamine-based solvents), physical absorption, mixed chemical/physical absorption, and adsorption on a solid.

a type of metamorphism that occurs in bodies of rock that have been deeply buried or greatly deformed by tectonic changes.

a mechanical device that displays numbers.

a unit of measure of the internal capacity of ships, which equals 100 cubic feet or about 2.8317 cubic metres.

the width of the hull of a mobile offshore drilling rig or a ship, measured at its points of greatest width and used to determine its registered tonnage.

the amount of a substance as indicated by the register on the meter.

see common cement.

a type of wire rope construction in which the wires in the wire rope strands are twisted in a direction opposite the strands themselves.

a valve used in process control systems that blends two fluids of different temperatures to achieve a desired output temperature.

see guidelines.

a device that reduces the pressure or volume of a fluid flowing in a line and maintains the pressure or volume at a specified rate. See full-opening safety valve.

in process control systems, the pressure that results when a fluid is sent to a pressure regulator to obtain a desired output pressure downstream from the regulator. The regulator is set to obtain the desired pressure and is designed to hold the desired pressure.

reduces the high-pressure pipeline gas to a lower usable pressure for the compressor and records the amount of gas consumed as fuel.

a measure of vapor pressure for petroleum fractions and their blends, measured in pounds per square inch (psi). The higher the RVP, the more volatile the product. The test procedure is reported as ASTM test method D 323-89 in the 1990 Annual Book of ASTM Standards, Section 5, Petroleum Products, Lubricants, and Fossil Fuels.

after recovery, the second system in an oil absorption plant in which the remaining methane is eliminated from the product stream, leaving only the desired product and absorption oil. See recovery, separation.

a proposed unit to express reluctance in a magnetic circuit. The rel has not, however, been universally accepted.

1. the ratio of the weight of a given volume of a substance at a given temperature to the weight of an equal volume of a standard substance at the same temperature. For example, if 1 cubic inch of water at 39°F (3.9°C) weighs 1 unit and 1 cubic inch of another solid or liquid at 39°F weighs 0.95 unit, then the relative density of the substance is 0.95. In determining the relative density of gases, the comparison is made with the standard of air or hydrogen. 2. the ratio of the mass of a given volume of a substance to the mass of a like volume of a standard substance, such as water or air.

the quotient of the absolute error divided by the true value of the measured quantity. This multiplied by 100 gives the relative error as a percentage.

the ratio of the amount of water vapor in the air to the amount it would contain if completely saturated at a given temperature and pressure. See absolute humidity.

in a marine riser system, movement caused by the structural compression that occurs when pressure is exerted on the ends of the pins in the riser connectors (Poisson’s effect), temperature differences between the fluid in the main riser and the fluids in the auxiliary lines, and bending loads imposed by deflections of the riser. Such motion of the riser connectors can cause fatigue cracking of the support flange if an adequate gap is not provided between the support flange and the coupling. See Poisson’s effect.

the permeability of a reservoir to oil, gas, or water relative to absolute permeability. Example: Kro = Ko/K, where Kro is defined as oil relative permeability; Ko is defined as oil permeability; and K is defined as absolute permeability. Similar relationships are true for gas and water. Consequently, in a reservoir where oil, gas, and water usually coexist, the absolute permeability reflects the productivity of the total rock pore environment. Relative permeability defines the ability of the rock to transmit a particular fluid. Relative permeability varies with various rock properties including saturation and wettability. Thus, productivity of oil, gas, and water vary with time as saturations change. Compare absolute permeability, effective permeability.

in financial economics the attractiveness, measured in terms of risk, liquidity, and return, of one financial instrument, which may be cash, ownership in an entity, or the right to receive cash from another financial instrument, relative to another, or, for a given instrument, of one maturity relative to another.

the ratio of absolute viscosity of the fluid being measured to the viscosity of water at 68°F. See absolute viscosity.

an invert-emulsion mud with a higher oil-to-water ratio than is usual.

a device in an electric circuit that senses electrical variations in the circuit and then makes or breaks one or more connections in the same or another electric circuit.

1. a statement filed by the lessee of an oil and gas lease indicating that the lease has been relinquished. 2. any spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, discarding, or disposing into the environment.

the ability of an item to operate as specified for an indicated time period. Often expressed as mean time between failures (MTBF) or mean time to failure (MTTF).

the elevations or inequalities of a land surface.

see pressure-relief valve.

a well drilled near and deflected into a well that is out of control, making it possible to bring the wild well under control. See wild well.

in electromagnetics, a measure of the opposition presented to magnetic lines of force (flux) in a magnetic circuit; it is analogous to resistance in an electric circuit.

in mathematical division, a quantity that results when one quantity does not divide evenly into another quantity. For example, 7 ÷ 2 = 3 with a remainder of 1. That is, 2 goes into 7 three times with 1 left over.

someone who holds a future interest in property and who will come into possession when the present possessory interest ends (as on the death of a life tenant). Compare life tenant.

usually referred to by its abbreviation. Sometimes used as an adjective (cargo remaining on board), but more often used as a noun (estimating the ROB). ROB includes water, oil, slops, oil residue, oil-water emulsions, sludge, and sediment.

cement placed in a wellbore after the primary cementing has occurred. Remedial cementing is used to repair holes in the casing, fill voids left behind in casing after primary cementing, stop lost circulation, and so on. Compare primary cementing.

the restoration of a well’s performance using chemicals such as acid and paraffin solvents to dissolve restricting materials in the perforations and near the wellbore.

to remedy or correct a problem with a situation or area.

the process of remedying or restoring an area or situation to its natural (or as close to natural as possible) state.

a system of blowout preventer controls, convenient to the driller, which can be used selectively to actuate valves at the master control panel. Also called secondary control panel. See driller’s BOP control panel.

a device placed on the rig floor that can be operated by the driller to direct air pressure to actuating cylinders that turn the control valves on the main BOP control unit, located a safe distance from the rig.

a set of controls, usually placed on the rig floor, that is manipulated to control the amount of drilling fluid being circulated through the choke manifold. This procedure is necessary when a kick is being circulated out of a well. See choke manifold.

an offshore pipeline-joining technique in which the connection process is directed from somewhere other than the immediate site, such as from a control panel on the platform deck. Two types of remote connection are the deflect-to-connect and direct pull-in techniques.

a centrally located station containing equipment to control and regulate operations in one or more fields.

see automatic choke.

an instrument that provides indications of pressure, vacuum, voltage, and so forth at a point distant from where the indications are actually taken.

refers to using infrared or other means to map an area; has largely replaced aerial photography.

an auxiliary set of controls for operating the blowout preventers.

that part of an automated lease that relays signals from the central computer to the end devices and relays status and alarm conditions from the end devices to the computer.

a separate or integral instrument system, used in conjunction with some other basic measuring means (such as an automatic tank gauge), that transmits the basic reading to some place other than the point of measurement.

in well service and workover, a piece of equipment installed in the well that does not require mechanical activation by a tool that is run on wireline or coiled tubing. Remote-actuated tools are often used in highly deviated or horizontal wells where mechanical intervention is costly and difficult or impossible to use.

in offshore operations, an underwater device controlled from a vessel on the water’s surface that is used to inspect and operate certain devices on subsea equipment, such as a blowout preventer stack, and that can be used in place of or in conjunction with diving personnel.

energy obtained from sources that are essentially inexhaustible (unlike, for example, the fossil fuels). Renewable sources of energy include wood, waste, geothermal, wind, photovoltaic, and solar thermal.

1. the closeness of the results of successive measurement of the same quantity carried out by the same method, by the same person with the same measuring instrument at the same location over a short period of time. 2. the ability of a meter and prover system to repeat its registered volume during a series of consecutive proving runs under constant operating conditions.

in process control systems, the time required for a controller to adjust itself back to its set point when a change in its input or output occurs.

the act of putting enough drilling fluid in the wellbore to replace the volume of any pipe or other tools that were removed.

1. the quantity of released hazardous materials that, when exceeded, must be reported under CERCLA. The EPA is charged with setting the allowable limits for releases of each hazardous material. If a release exceeds the EPA reportable quantity, CERCLA requires that the owners or operators of the facility notify the National Response Center immediately. 2. SARA (section 304) also requires facilities that release a reportable quantity of an EHS or CERCLA hazardous substance to notify the SERC and the LEPC immediately. This requirement is similar to the CERCLA requirement to notify the NRC in case of reportable releases. Like CERCLA, SARA exempts federally permitted releases, continuous releases, any release contained on site, as well as other CERCLA exemptions from RQ reporting requirements. In addition, SARA requires a written follow-up report to be submitted to the SERC and the LEPC as soon as practicable after the release.

a small portion extracted from the total volume of material that contains the same proportions of the various flowing constituents as the total volume of liquid being transferred. The precision of extraction must be equal to or better than the method used to analyze the sample.

to increase or maintain reservoir pressure by injecting a pressurized fluid (such as air, gas, or water) to effect greater ultimate recovery.

1. the closeness of the results of measurements of the same quantity where the individual measurements are made by different observers using different methods with different measuring instruments at different locations after a long period of time, or where only some of the factors listed are different. 2. the ability of a meter and prover system to reproduce results over a long period of time in service where the range of variation of pressure, temperature, flow rate, and physical properties of the metered liquid is negligibly small.

in waterflooding, the entrapment of oil in rocks of lower permeability, where gas space has developed during primary production. The resaturated oil is bypassed by the waterflood as the water seeks the path of highest permeability.

in offshore operations, any boat that may be used in saving the lives of personnel at sea. For example, the United States Coast Guard (USCG) possesses a fleet of vessels called cutters that USCG uses for many purposes, ranging from preventing smuggling to breaking ice. However, in times when lives are in peril at sea, any of these vessels could be called to perform rescues. Similarly, the standby boat that is usually tied up next to an offshore facility can also perform rescues if needed.

a U.S. Department of Transportation agency that oversees the Office of Pipeline Safety, intermodal containers, highway portable tanks, railroad cars, and anything used in interstate or international commerce not regulated by the coast guard. Under OPA, RSPA has authority over onshore oil and hazardous materials pipelines that are used in interstate commerce. Address: 1200 New Jersey Avenue, SE, 2nd floor; Washington, DC 20590; (202) 366-4433.

the buoyancy above the waterline that keeps a floating vessel upright or seaworthy when the vessel is subjected to wind, waves, currents, and other forces of nature or when the vessel is subjected to accidental flooding.

capacity in excess of that required to carry peak load.

1. (obsolete) a mud pit in which a supply of drilling fluid is stored. 2. a waste pit, usually an excavated earthen-walled pit. It may be lined with plastic or other material to prevent soil contamination.

a special mud tank that holds mud that is not being actively circulated. A reserve tank usually contains a different type of mud from that which the pump is currently circulating. For example, it may store heavy mud for emergency well-control operations.

the unproduced but recoverable oil or gas in a formation that has been proved by production.

the total estimated amount of recoverable hydrocarbons in a reservoir.

1. a subsurface, porous, permeable rock body in which oil and/or gas has accumulated. Most reservoir rocks are limestones, dolomites, sandstones, or a combination. The three basic types of hydrocarbon reservoirs are oil, gas, and condensate. An oil reservoir generally contains three fluids-gas, oil, and water-with oil the dominant product. In the typical oil reservoir, these fluids become vertically segregated because of their different densities. Gas, the lightest, occupies the upper part of the reservoir rocks; water, the lower part; and oil, the intermediate section. In addition to its occurrence as a cap or in solution, gas may accumulate independently of the oil; if so, the reservoir is called a gas reservoir. Associated with the gas, in most instances, are salt water and some oil. In a condensate reservoir, the hydrocarbons may exist as a gas, but, when brought to the surface, some of the heavier ones condense to a liquid. 2. a container or vessel that stores fluid, as a reservoir on an accumulator that holds hydraulic operating fluid.

see formation damage.

see reservoir drive mechanism.

the process in which reservoir fluids are caused to flow out of the reservoir rock and into a wellbore by natural energy. Gas drive depends on the fact that, as the reservoir is produced, pressure is reduced, allowing the gas to expand and provide the principal driving energy. Water drive reservoirs depend on water and rock expansion to force the hydrocarbons out of the reservoir and into the wellbore. Also called natural drive energy.

nonuniformities in the structure of properties of petroleum reservoirs, such as lenticular formation, pinch-outs, faults that cut across the reservoir, shale barriers, and variations in permeability.

a description or analogy constructed to help visualize something that cannot be observed directly, such as the structure, porosity, and permeability of geological formation.

oil in place in the reservoir; unproduced oil. Compare stock tank oil.

the average pressure within the reservoir at any given time. Determination of this value is best made by bottomhole pressure measurements with adequate shut-in time. If a shut-in period long enough for the reservoir pressure to stabilize is impractical, then various techniques of analysis by pressure buildup or drawdown tests are available to determine static reservoir pressure.

a permeable rock that may contain oil or gas in appreciable quantity and through which petroleum may migrate.

computer model of a reservoir to predict reservoir behavior and to show production over time, allowing decisions about managing the reservoir to be made. The technique consists of digitizing data from appropriate geologic maps and engineering studies and entering them into a computer program, called the model. The model uses past and present values for each parameter of reservoir behavior.

the average temperature within the reservoir, measured during logging, drill stem testing, or bottomhole pressure testing using a bottomhole temperature recorder.

see formation volume factor.

in process control, the action of maintaining a prescribed output through reset action. v: to restore a setting or input to its original value.

shortened form of residual.

see residuals.

the heavier oils that remain after the distillate fuel oils and lighter hydrocarbons are distilled away in refinery operations that conform to ASTM Specifications D396 and 975.

the portion of hydrocarbons that cannot be removed by ordinary producing mechanisms when a porous reservoir has been saturated with hydrocarbons. This value is usually a specific percentage of the pore volume. In the case of gas, the volume, measured at standard conditions, that is retained in a reservoir as residual gas saturation is an inverse function of the pressure, due to the effect of the gas laws.

the relatively small amount of magnetism that virtually all metallic objects that contain iron retain as a result of the magnetic influences. It affects magnetic compasses by attracting the compass needle away from actual magnetic north to give a false reading.

1. in improved recovery, oil remaining in a reservoir after an improved recovery method has been applied and displacement has occurred. 2. in petroleum refining, the combustible, viscous, or semiliquid bottoms product from crude oil distillation, used as adhesives, roofing compounds, asphalt, low-grade fuels, and sealants.

the heavy refined hydrocarbons that are used as fuels. Bunker C oil, which is sometimes used to fuel ships, is an example of a residual.

1. a natural gas mixture essentially of methane and ethane. 2. natural gas after it has been processed and almost all hydrocarbons other than methane and some ethane removed.

plant residue gas delivered back to the producer for use in lease operations.

provision in many casinghead gas purchase contracts that provides that all of the seller’s properties covered by the contract will be treated as a single property in determining whether the producer has taken more residue gas for use in operations than the quantity to which he or she is entitled.

a semisolid or solid complex, amorphous mixture of organic compounds having no definite melting point or tendency to crystallize. Resins may be a component of compounded materials that can be added to drilling fluids to impart special properties to the fluid.

an oilwell cement that is composed of resins, water, and portland cement and that provides an improved cement bond. It is mainly used in remedial operations, because its high cost prohibits its use for routine cementing of casing.

opposition to the flow of direct current caused by a particular material or device. Resistance is equal to the voltage drop across the circuit divided by the current through the circuit.

in process control, an electronic device that senses temperature by means of changes in electrical resistance caused by changes in temperature.

a thermometer that uses an electrical resistor to detect temperature and electrical means to measure and indicate temperature.

a measure of a resistor’s accuracy, usually stated in percent. For example, if a 2,400-ohm resistor has a tolerance of 5 percent, its resistance should vary no more than 5 percent of 2,400 ohms, either up or down, or its resistance should be no less than 2,280 or more than 2,520 ohms.

an electrical circuit that has a resistance and a capacitance in series, and in which inductance is negligible.

the electrical resistance offered to the passage of current; the opposite of conductivity. Resistivity data can help identify the characteristics of a formation.

a record of the resistivity of a formation. Usually obtained when an electric log is run. See resistivity well logging.

an instrument for measuring the resistivity of drilling fluids and their cakes.

the recording of the resistance of formation water to natural or induced electrical current. The mineral content of subsurface water allows it to conduct electricity. Rock, oil, and gas are poor conductors. Resistivity measurements can be correlated to formation lithology, porosity, permeability, and saturation and are very useful in formation evaluation. See electric well log.

a component that tends to impede the flow of electric current, usually without any inductive or capacitive effects.

the smallest change in the quantity measured to which the instrument will react with an observable change in an analog or digital indication.

the vibration in mechanical parts caused by high speeds or oil film.

of sucker rods, the frequency at which the periods of resonance are at a maximum.

a federal regulatory program designed to ensure responsible management of hazardous waste at all levels of contact, i.e., generation, transportation, treatment, storage, and disposal; regulates the management of on-land disposal of all solid wastes. This comprehensive program is designed to protect human health and the environment from the unintentional exposure to solid waste that is identified as “hazardous waste.” Also institutes a “cradle-to-grave” monitoring program that closely tracks and regulates the handling of hazardous waste from the time the waste is first generated until it is disposed.

concentrations of naturally occurring liquid or gaseous hydrocarbons in the earth’s crust, some part of which are currently or potentially economically extractable. Some categories of resources are (1) from the economic standpoint, economic (recoverable, commercial), marginally economic, and subeconomic; and (2) from the geological standpoint, identified (subdivided into measured, indicated, and inferred), and undiscovered.

in process control, the difference in time between a command from the set point to the actual change in the controlled variable.

in a thermometer, the time required to indicate 63.2% of the magnitude of a change in the measured temperature.

1. the force exerted by a centralizer against the borehole to keep the pipe away from the borehole wall. 2. horizontal force required by a mooring vessel to counteract the forces of the environment and maintain the vessel on station.

a classification that states that the rig can operate only in a specific geographic area named in its classification documents. Restricted rigs meet modified requirements relating to stability, including stability in severe weather, for a specific region, such as the Gulf of Mexico.

the observed value of a variable determined by a single measurement.

the force that occurs from the combined effects of two or more forces.

a cast-iron or magnesium drillable tool consisting of a packing assembly and a back-pressure valve. It is used to close off the annular space between tubing or drill pipe and casing to allow the placement of cement or fluid through the tubing or drill pipe at any predetermined point behind the casing or liner, around the shoe, or into the open hole around the shoe.

see cementing head.

in subsea completions, a valve located at the lower end of the completion-workover riser. When closed, it keeps fluid within the riser when it is necessary for the surface vessel to disconnect from the riser in an emergency.

a steel ring that holds the cone on the bearing assembly in some journal bearing bits.

a cement in which the thickening time is extended by adding a chemical retarder.

1. a substance added to cement to prolong the setting time so that the cement can be pumped into place. Retarders are used for cementing in high-temperature formations. 2. a slow-to-evaporate solvent added to paint, which slows down the speed of paint’s drying. A paint retarder improves a paint’s application properties or produces a better film.

see retentivity.

in magnetism, the tendency of an unmagnetized iron or steel bar to retain, or hold, its magnetism after it is magnetized. Iron or steel with low retentivity loses its magnetism relatively quickly, while an iron or steel with high retentivity keeps its magnetism relatively longer.

an instrument used to distill oil, water, and other volatile materials in a mud to determine oil, water, and total solids contents in volume-percent. Also called a still.

a device that measures the saturation, or the amount, of each fluid in a core sample by distilling the fluid from the core with heat. Also called a retort still.

see retort oven.

in an oscilloscope, the brief instant at which the voltage driving the oscilloscope’s beam suddenly decreases and drives the beam to the left of the screen.

a bit that can be changed by wireline operations without withdrawing the drill string. Field tests have indicated its economic feasibility, but its practicability is undetermined.

a piston-type valve that can be used to reposition a string float up the hole to avoid the use of multiple string floats. It consists of a retainer sub and a wireline retrievable piston that fit inside the sub. It allows flow down the string but not up. The float can be retrieved with wireline and a second (or third) retainer sub can be set higher into the drill pipe during a connection.

a packer that can be pulled out of the well when it fails, to be repaired or replaced.

a bottomhole choke run on wireline and landed in the tubing string.

condensation or vaporization that is the reverse of expected gas performance. A decrease in pressure or increase in temperature causes condensation. An increase in pressure or decrease in temperature causes vaporization.

see retrograde reservoir.

a reservoir in which the pressure is high and the hydrocarbon content is completely in a gaseous or supercritical phase at initial conditions. As the pressure drops because of production, the heavier hydrocarbon components condense, forming liquids within the reservoir. Such action is the retrograde phenomenon. If the reservoir pressure is completely depleted, only a small portion of these liquids will revaporize and be recovered.

a U-shaped section of piping that connects two other pipes parallel to each other.

the permeability of a reservoir that is available for production after completion, relative to the theoretical undamaged permeability. It is a measurement similar to skin damage. See formation damage, skin.

the mud, cuttings, and so forth, that circulate up the hole to the surface.

in economics, income that a company receives from its normal business activities, usually from the sale of goods and services to customers.

1. the back or rear part of something. 2. A change to an opposite position, condition, or direction. 3. A change in fortune from better to worse; a setback. 4. A mechanism, such as a gear in a motor vehicle, which is used to reverse movement, or the position or operating condition of such a mechanism. 5. Movement in a direction that is opposite of forward.

where a p-type and an n-type semiconductor are joined, a condition in which no current flows in the semiconductors because the negative terminal of a battery is connected to the lead of the p-type material and the positive terminal of the battery is connected to the lead of the n-type material. Compare forward bias. See n-type semiconductor, p-type semiconductor.

see Zener breakdown.

the course of drilling fluid downward through the annulus and upward through the drill stem, in contrast to normal circulation in which the course is downward through the drill stem and upward through the annulus. Seldom used in open hole, but frequently used in workover operations. Also referred to as “circulating the short way,” since returns from bottom can be obtained more quickly than in normal circulation. Compare normal circulation.

a type of in situ combustion in which the combustion front moves counter to the direction of the injected air. Air is injected into a production well and burning is started near the well. When the combustion zone has advanced a short distance from the well, air injection is stopped from the production well and started from an adjacent injection well. The fire advances toward the injection well, but the oil moves toward the production well. This method may be used with very viscous oils. Compare forward combustion.

a device installed in a diesel-electric system that disconnects a generator from the system when an engine is underloaded and the generator attached to it behaves like a motor. A generator acting like a motor draws current from the system, instead of supplying current. The generator acting like a motor then drives the underloaded engine, which can severely damage the engine.

a sudden decrease in the rate of penetration. When drilling with an oil mud and diamond bit, and an abnormally high-pressure formation is penetrated, the penetration rate may decrease rather than increase. An increase is a drilling break.

a relatively rare oilfield emulsion composed of globules of oil dispersed in water. Most oilfield emulsions consist of water dispersed in oil.

a dip-slip fault along which the hanging wall has moved upward relative to the footwall. Also called a thrust fault.

a method of joining a pipeline to a subsea riser on an offshore platform. In this method the pipe is welded together on the platform itself and then fed down through a guide tube to the seafloor. Compare J-tube method.

a method of desalting brackish or salt water by passing it through a membrane that is not permeable to salt. See osmosis.

to displace the wellbore fluid back to the surface; to displace tubing volume back to the pit.

a device that increases an engine’s speed by decreasing the positive voltage going to the electric actuator and governor. As the engine needs more fuel to go faster, the reverse-acting actuator decreases the positive voltage to make the governor increase the fuel. Compare direct-acting electric actuator. See governor.

in reference to tubing under the effects of temperature changes, sucker rod pumping, or high external pressure, to decrease in diameter while increasing in length. Compare balloon.

a fishing tool that is lowered into the hole during normal circulation and then produces reverse circulation to create a vacuum so that junk is sucked inside the tool. Also called a jet-powered junk basket.

see perforate underbalanced.

on offshore installations with grated decks, grating so constructed that it may be installed either side up, with no difference in appearance or carrying capacity. See grating.

a device containing a mercury-in-glass thermometer, which may be inverted after the thermometer has reached thermal equilibrium with the oil in which it is immersed. The inversion breaks the mercury thread, disconnecting it from the sensing element and allowing it to run down to the other end of the thermometer stem. The instrument is then drawn to the surface and the recorded temperature, which remains unchanged until the instrument is reset, can then be read.

a well-servicing hand who cleans out wellbores.

a future interest created by law when an estate is, for example, leased. The reversion is not conveyed but is retained to take effect later in favor of the grantor or his or her heirs. See term minerals.

the number of full rotations completed in one minute around a fixed axis. Generally used in measuring the rotational speed of a mechanical unit.

to restore production from an existing formation when it has fallen off substantially or ceased altogether. See work over.

a dimensionless number defined as Re = DuP ÷ m where D = inside diameter of the pipe, u = mean flow velocity, P = density of the fluid, and m = dynamic viscosity, all in consistent units.

recovery factor.

a brand of hydraulic connector used in subsea marine riser systems. It is similar to Cameron’s Load King connector but has a tensile load rating of 2 million pounds (900 tonnes). See Load King connector.

reformulated gasoline.

the study of the flow of gases and liquids of special importance to mud engineers and reservoir engineers.

a resistor that is used to vary the electrical current flow in a system.

a light-colored, fine-grained volcanic rock; the extrusive equivalent of granite.

a kind of conductor in which two wires are separated a short distance from each other by an insulating material. The conductor thus has the appearance of a flat ribbon. Ribbon line is often used to attach a television antenna to the television set and has an impedance of 300 ohms. See impedance.

the amine leaving the bottom of the contactor. It is the lean amine plus the acid gases removed from the gas by the lean amine.

a gas that is suitable as feed to a gas processing plant and from which products can be extracted.

water-laden glycol.

a lean oil that has absorbed heavier hydrocarbons from natural gas.

a vessel used in gas processing plants to remove methane from rich oil.

the bottom section of the separation tower between the feed gas and the reboiler where light gas components are removed. Also called stripping section.

see still.

a separately listed provision in a lease. Also called an exhibit or allonge.

in diamond bits, the setting of small diamonds on raised ridges on the cutting surface of the bit. Compare surface set.

a hole bored through a machined metal piece (as in a steel pin in a traveling block sheave) through which a lubricant travels.

the zone along which crustal plates separate because of slowly diverging convection currents in the semisolid, deformable mantle. As the rift widens and the land masses on both sides move apart, new oceanic crust is formed. Since the Mid-Atlantic rift zone opened about 200 million years ago, North and South America have been moving away from Europe and Africa at a rate of 1H-inches a year.

the derrick or mast, drawworks, and attendant surface equipment of a drilling or workover unit.

see rotary helper.

to dismantle a drilling rig and auxiliary equipment following the completion of drilling operations. Also called tear down.

the area immediately around the rotary table and extending to each corner of the derrick or mast-that is, the area immediately above the substructure on which the rotary table and other equipment rest. Also called the derrick floor, drill floor.

the metal parts (with the exception of nails, bolts, guy wires, and sand lines) used in the construction of a standard cable-tool rig.

an employee of a drilling contractor who is in charge of the entire drilling crew and the drilling rig, providing logistics support to the rig crew and liaison with the operating company.

see unit operator.

a person in the employ of a drilling contractor whose duty station is on the rig. This person is responsible for coordinating safety and training activities on the rig and supporting the contractor’s, the operating company’s, and the government authority’s safety and training requirements. This person’s duties may include monitoring the safety performance of rig personnel, conducting rig-site training courses, maintaining training records, orienting visitors on the rig, and maintaining liaison between the rig and the contractor’s administrative offices.

see toolpusher.

see toolpusher.

to prepare the drilling rig for making hole, i.e., to install tools and machinery before drilling is started.

usually, mobile and compact hydraulic equipment that uses a conventional workover or drilling rig to perform work on the well under pressure. For example, rig assisted units allow completions or workovers to be safely and routinely performed under pressure.

see rig up.

an angle of 90 degrees.

in mathematics, a triangle in which one of the angles is a right angle. See right angle.

the statement of the fact that if the coil is grasped in the right hand with the fingers wrapped around it in the direction of the current flow, the thumb points toward the north pole.

the statement of the fact that if the fingers of the right hand are placed around a wire so that the thumb points in the direction of the current flow, the fingers point in the direction of the magnetic field produced by the wire.

the legal right of passage over public land and privately owned property; also the way or area over which the right exists. The width of a right-of-way varies according to contract specifications and individual easements, but it is generally between 50 and 100 feet (15 and 30 metres).

in pipeline construction, the process of returning a right-of-way to its original condition or better after the pipeline has been completed. Right-of-way restoration depends on legal stipulation in the contract with the pipeline owner and agreements made with individual landowners.

the horizontal distance between the center of gravity and a vertical line through the center of buoyancy of a floating offshore vessel that is displaced from the upright position. See center of buoyancy, center of gravity.

the force that causes a floating vessel that is heeled over to attain an upright position.

the turning force (torque) that tends to restore a floating vessel that is heeled over to its upright position.

see rigid platform rig.

an offshore platform rig that does not move with the motion of the wind and sea.

on fixed production platforms, a stationary pipe clamped to the platform’s legs and connected to flow lines on the seabed. Because the platform is fixed-it does not move with waves, currents, or wind-it is not necessary for the riser to move, or flex. Wells are produced through a rigid riser and treating fluids are injected into producing wells through a rigid riser.

a program developed under the National Fishing Enhancement Act that led to the state sponsorship of the conversion of rigs to artificial reefs in the Gulf of Mexico.

run-in-hole.

see piston ring, shell.

soft iron, low-carbon steel or stainless steel gaskets used to seal high-pressure flanges. Also called ring gasket.

in a rotary table assembly, a circular, ring-shaped device with projections (teeth) that engage a beveled gear (a pinion) on the end of a drive shaft. The drive shaft is usually driven by a chain-and-sprocket arrangement from the drawworks. When engaged, the drive shaft turns the pinion, which meshes with the ring gear, to turn the rotary table.

the grooves that hold the piston rings in pistons.

a special type of flanged connection in which a metal ring (resting in a groove in the flange) serves as a pressure seal between the two flanges.

a form of corrosion sometimes found in the tubing of condensate wells. It occurs in a ring a few inches from the upset. Cause of ringworm corrosion has been traced to the upsetting process, in which heat required in upsetting causes the heated end to have a different grain structure from the rest of the pipe. Normalizing prevents this condition.

a claw-shaped, plowlike attachment used on a bulldozer to loosen rock and locate solid formations that may require explosives in clearing a right-of-way for pipeline construction.

the alternating current component in the output of a direct current power supply, which arises in the power supply because of incomplete filtering or from a direct current generator.

to space logs and timbers evenly along the length of a pipeline right-of-way to stabilize soil in swamps or wet areas.

1. a pipe through which liquid travels upward. See riser pipe. 2. a common connection for pipelines consisting of a predetermined bend in the pipeline by as much as 90 degrees from the seafloor.

a fitting installed on top of the lower marine riser package’s (LMRP’s) flex joint. It is a fitting to which the first riser joint is attached to the LMRP.

an acoustic or electronic device used to monitor the angle of the flex joint on a floating offshore drilling rig. A small angle should usually be maintained on the flex joint to minimize drill pipe fatigue and wear and damage to the blowout preventers and to maximize the ease with which tools may be run. Also called azimuth angle indicator.

see riser pipe.

the caving in of a riser joint or several riser joints that can occur if the pressure inside the riser drops below external seawater pressure.

the ability of the riser pipe to withstand its tendency to cave in if pressure inside the riser drops below external seawater pressure.

a fitting attached to the end of each riser joint that allows the joints to be attached to one another.

the act of removing the riser pipe (marine riser) from its attachment to the subsea blowout preventer stack.

on a riser connecter, the flat, ring-shaped fitting that provides a place for riser joints to be attached to each other.

a special tool that enables riser joints, as well as the telescopic joint, to be raised and lowered into and out of the water. See hydraulic riser handling tool, mechanical riser handling tool.

see riser pipe.

see riser connector.

a device used on offshore floating drilling rigs that employ marine riser pipe to pick up or lay down riser pipe joints when the pipe is being run or removed from the seafloor. See riser pipe.

the slight increase in mud weight used to offset friction losses that occur as the mud is circulated through the riser in a subsea blowout preventer system.

the pipe and special fittings used on floating offshore drilling rigs to establish a seal between the top of the wellbore, which is on the ocean floor, and the drilling equipment, located above the surface of the water. A riser pipe serves as a guide for the drill stem from the drilling vessel to the wellhead and as a conductor of drilling fluid from the well to the vessel. The riser consists of several sections of pipe and includes special devices to compensate for any movement of the drilling rig caused by waves. Also called marine riser pipe, riser joint.

a short length-usually, from 5 to 40 feet (1 to 12.2 metres) long-of riser pipe that is used to space out the riser assembly as it is run to various water depths. See space out.

a device attached to a rig’s rotary table that supports riser pipe on a floating offshore drilling vessel.

see riser pipe.

see riser pipe.

an assembly of strong cables (lines) connected to the outer barrel of the telescopic joint and a hydropneumatic piston-and-cylinder sheave assembly. The tensioning system supports the weight of the riser joints by applying force (tension) to the outer barrel of the telescopic joint. Tensioner lines are connected to a tensioner ring or to fixed padeyes on the outer barrel. The applied tension must remain constant while compensating for vessel heave.

a cable that supports the marine riser while compensating for vessel movement. See riser tensioner.

see riser-support spider.

in deepwater applications on floating rigs, a device placed between the rotary table and riser-support spider to compensate for offset caused by ocean movements. Hydraulic cylinders, or flex elements, support the weight of the spider, the entire riser string, and BOP assembly. It also cushions shock loads imparted on the system. See riser-support spider.

a fitting placed in the rotary table of an offshore floating rig which supports a joint of riser pipe as the pipe is being lowered into or pulled from the water. The spider consists of a base plate and top plate with a series of support dogs, or arms, between them. The dogs support the riser joint under the riser joint’s support flange. Hydraulic cylinders force the support dogs inward and under the riser joint support flange. They are also retracted hydraulically to allow the riser joints to pass through. On some riser spiders, the support arms are engaged and disengaged manually. The riser and BOP assembly rest on the riser-support spider as the crew picks up and adds each new joint to the string. The riser spider’s ID is the same as the rotary table’s ID, and the base plate is designed for the specific rotary table with which it is used.

an unconventional deepwater offshore drilling technique used on floating drilling rigs. The technique utilizes relatively small diameter pipe as a mud return line from the seafloor instead of a large diameter marine riser. Riserless drilling eliminates the need for a large rig that must be able to handle the enormous weights of riser pipe as well as be able to store it. Moreover, drilling without a riser does not require that the rig be able to store and handle the large amounts of mud needed to circulate through the riser. Finally, riserless drilling eliminates the need to set numerous strings of casing to solve the problem of protecting formations whose fracture pressure is close to the pressure required to prevent kicks.

the activity of assigning probabilities to the expected outcomes of a drilling venture.

a document prepared by a project manager to foresee risks, to estimate their effect on a project, and to create response plans to alleviate them. A risk is an event or a condition that can positively or negatively affect the project’s objectives. Risk management plans should assess risks and develop plans to address them.

a term that relates to the risk of an investment and the amount of money (return) that can be expected from the investment. As the risk of an investment increases, the potential return usually increases as well. In short, the higher the risk involved with the investment, the higher the returns may be.

a type of special pipeline construction used when a pipeline must cross a river or stream. Types of river crossings include aerial crossings, conventional crossings, and directionally drilled crossings.

(sometimes called the Refuse Act) congressional act that authorizes the secretary of the army through the U.S. Army Corps of Engineers to issue permits for the placement of structures or the discharge of refuse in navigable waters of the United States.

Radio Manufacturers Association.

reaming; used in drilling reports.

robot maintenance system.

root-mean-square value.

laying of a pipeline under a roadbed or through a road.

remaining on board.

a system which services underwater equipment.

a hardened aggregate of different minerals. Rocks are divided into three groups on the basis of their mode of origin: igneous, metamorphic, and sedimentary.

to initiate flow by alternately bleeding pressure from, and closing off the casing and tubing of, a well that contains liquid.

name for the first roller cone bits; now almost obsolete. See roller cone bit.

see cuttings.

the possible sequences of events, all interrelated, by which rocks may be formed, changed, destroyed, or transformed into other types of rock. The events include formation from magma, erosion, sedimentation, and metamorphism.

excavating a trench in rock or rocky soil.

a drill generally powered by compressed air and used to drill holes for explosives. Rock drills may be required in pipeline right-of-way grading and in ditching.

(slang) a geologist.

1. the fine-grained material between larger grains in which the larger grains are embedded. A rock matrix can be composed of fine sediments, crystals, clay, or other substances. It is the solid portions of a porous rock not including the pores themselves. 2. the material in which diamonds on a diamond bit are set. 3. in mathematics, a rectangular array of numbers form vector space.

see petroleum.

see geostatic pressure.

a distinctive body of rock that can be identified by its lithologic or structural features regardless of its fossils or time boundaries; commonly, a formation. Compare time stratigraphic unit.

all of the properties relating to the grain-to-grain relationships of a rock. Textural properties include chemical composition, grain shape and roundness, grain size and sorting, grain orientation, porosity, and permeability. See clastic texture, crystalline texture.

a bell-crank device that transmits the movement of the pushrod to the valves in an engine.

an arbitrarily defined measure of resistance of a material to indentation under static or dynamic load.

rich-oil demethanizer.

a device used to unscrew rods when the pump is stuck or sanded up and the rods and tubing must be pulled together.

see connecting rod bearing.

a ram device used to close the annular space around the polished rod or sucker rod in a pumping well.

on an engine’s piston rod, a part on the bottom of the rod that is bolted onto the top part of the rod. To install a piston rod onto the crankshaft, one half of the rod bearing is inserted into the top part of the rod and the other half into the rod cap. The top part of the rod and the rod cap are then placed on the crankshaft and the cap bolted to the top part.

see rod hold-down cup.

a device used to pull or to run sucker rods. They have a bail attached to the rod hook.

lightning arrester assembly using two rods end-to-end with the gap separating rods determining arcing voltage.

a device used to hang sucker rods on the mast or in the derrick.