Glossary

moment of inertia.

current.

a steel bar that has a cross-sectional shape that resembles the letter I.

induction-electric survey.

internal-external upset end.

an energy loss in an electric circuit caused by the resistance in ohms of the copper to the flow of current. Equal to the current squared times the resistance in ohms. Also called copper loss.

International Association of Classification Societies.

International Association of Drilling Contractors.

inside blowout preventer.

Interstate Commerce Commission.

a fog, composed of ice crystals, that occurs in moist air during cold, calm conditions in winter. It may be produced artificially by the combustion of fuel in cold air. This type of fog is common in the Arctic.

floating sea ice formed by the merging of floes.

the abrasion of material in contact with moving ice in a sea, ocean, or other body of water.

a large, floating mass of ice detached from a glacier.

initial circulating pressure; used in drilling reports.

incident command system.

inside diameter.

1. a gas whose molecules are infinitely small and exert no force on each other. 2. a gas that obeys Boyle’s law and Joule’s law. Also called a perfect gas.

a hypothetical ideal gas equation developed by Benoît Paul Émile Clapeyron in 1834 stating that all gases occupy an equal volume at the same conditions of temperature and pressure. The ideal gas law can be stated as Pv = RT or PV = nRT where R = a proportionality factor, T = absolute temperature, v = volume of one mol of gas, n = number of mols of gas, V = volume of n mols of gas, and P = absolute pressure.

see kinetic pressure.

all of the words, letters, numbers, and marks carried by a measuring instrument to indicate its origin, destination, operation, characteristics, method of use, and so on.

on a flow recorder, the record of the static and differential spring ranges.

(slang) 1. a shovel. 2. a thread profile gauge.

to operate an engine without applying a load to it.

a pulley or sprocket used with belt or chain drives on machinery to maintain desired tension on the belt or chain.

immediately dangerous to life or health.

a statement that asserts that if one thing is true then another thing is also true. Mathematically, the operation is, “If p, then q.”

Institut Francais du Petrole.

instrument flight rules.

igneous; used in drilling reports.

insulated-gate bipolar transistor.

integrated gasification combined cycle.

a rock mass formed by the solidification of magma within the earth’s crust or on its surface. It is classified by chemical composition and grain size. Granite is an igneous rock.

the ability of a substance to catch fire, burn.

a coil in the ignition system of an engine that stores energy in a magnetic field slowly and releases it suddenly to cause a spark that ignites the fuel mixture in a cylinder.

the ability of a fuel to ignite when it is injected into the compressed-air charge in a diesel engine cylinder. It is measured by an index called the cetane number.

the temperature at which a particular vapor burns.

(slang) the heavier end of any device (such as a length of pipe or a wrench).

immersion heater temperature switch.

an iron-black mineral of composition FeTiO3 or Feo•TiOx, with a specific gravity of about 4.67, sometimes used for increasing the density of oilwell cement slurries.

radar carried on airplanes or orbital vehicles that forms images of the terrain.

displacement of hydrocarbons or fluids in a reservoir by increasing the wetting phase saturation. See wetting phase.

in sedimentary rocks, the arrangement of pebbles in a flat, overlapping pattern like bricks in a wall. Often shown by stream gravel deposits.

Intergovernmental Maritime Consultative Organization.

(HAZWOPER) having an atmospheric concentration of any toxic, corrosive, or asphyxiant substance that poses an immediate threat to life or that would cause irreversible or delayed adverse health effects or that would interfere with an individual’s ability to escape from a dangerous atmosphere. n: 1. a substance that is immediately dangerous to life or health. 2. a situation in which immediate danger conditions exist.

a temperature-sensitive device installed on engines in extremely cold climates, such as in Alaska and Siberia. Before the engine is started, the switch senses very cold coolant and turns on an immersion heater in the coolant tank, thus ensuring that the engine warms up quickly.

not capable of mixing together (like oil and water) or attaining homogeneity.

in enhanced recovery, a gas that is injected into the reservoir that does not mix with the existing hydrocarbons in the reservoir. In some cases, injecting immiscible gas followed by injecting water can remove hydrocarbons that initial recovery methods left behind.

immiscible gas injected into injection wells in alternating steps with water to improve recovery.

International Maritime Organization.

Instituto Mexicano del Petróleo (Mexican Petroleum Institute).

pressure exerted by a moving fluid on a plane perpendicular to its direction of flow.

1. an instrument that constrains air flow past a sensitized sampling plate. 2. a machine or part that operates by striking blows. 3. a rotary hammermill that crushes ore by impacting it against crushing plates or elements.

in an alternating current (AC) circuit, the circuit’s total opposition to current flow. Impedance is similar to resistance in a direct current (DC) circuit. Just as resistance is measured in ohms, so too is impedance. When connecting certain AC components, such as a microphone to an amplifier, it is important for both components to have the same, or very close to the same, impedance; otherwise, the connected components may not operate properly.

a set of mounted blades used to impart motion to a fluid (e.g., the rotor of a centrifugal pump).

early manifestation or indication of a blowout.

preventing the passage of fluid. A formation may be porous yet impermeable if there is an absence of connecting passages between the voids within it. See permeability.

see impermeable.

see if-then operation.

an obligation or benefit not specified in an oil and gas lease but held by the courts to be implicit in such lease; for example, an obligation on the part of the lessee to drill an initial well.

(OSHA) the first business with employees within the customs territory of the United States that receives hazardous chemicals produced in other countries for the purpose of supplying them to distributors or employers within the United States.

a fixed-head bit that contains small particles (grit) of natural diamonds embedded throughout a tungsten carbide matrix. The diamonds are generally smaller than those used in conventional natural diamond bits. Impregnated diamond bits drill in a similar fashion to natural diamond bits, but, when the diamonds become worn and torn out of the matrix, new ones are continually being exposed. Impregnated diamond bits can drill the hardest, most abrasive formations at high rpm.

in an electrical circuit, voltage applied to the circuit or to a device in the circuit.

anode to which an external source of positive electricity is applied (such as from a rectifier or DC generator). The negative electricity is applied to a pipeline, casing, or other structure to be protected by the impressed-current method of cathodic protection.

a block with lead or another relatively soft material on its bottom. It is made up on drill pipe or tubing at the surface, run into a well, and set down on the object that has been lost in the well. The block is retrieved and the impression is examined. The impression is a mirror image of the top of the fish; it also indicates the fish’s position in the hole, i.e., whether it is centered or off to one side. From this information, the correct fishing tool can be selected.

a lead-filled cylindrical device used to ascertain the shape of the top of a fish.

used in wire rope construction definitions.

the introduction of artificial drive and displacement mechanisms into a reservoir to produce a portion of the oil unrecoverable by primary recovery methods. See enhanced oil recovery.

a special coupling between the camshaft and the magneto of a large engine. At cranking speeds the magneto is made to rotate in quick spurts to produce large pulses of voltage at the time of ignition for each cylinder.

the increase in the weight in sucker rods in fluid plus the weight of the fluid, caused by the effects of inertia or acceleration. For example, if an increased pumping rate causes an inertial effect of 30% of the weight of the rods in fluid plus the weight of the fluid, the impulse factor will be 1.3.

in an AC circuit, voltage and current are in phase when they begin, reach a maximum in the same direction, and return to zero at exactly the same time. Two or more alternating emfs of the same frequency are in phase when their polarities and instantaneous values occur at the same time.

in the reaction mixture, unstable molecules must be synthesized within the reaction mixture and cannot be isolated.

a method of improved recovery in which heat is generated within the reservoir by injecting air and burning a portion of the oil in place. The heat of initial combustion cracks the crude hydrocarbons, vaporizes the lighter hydrocarbons, and deposits the heavier hydrocarbons as coke. As the fire moves from the injection well in the direction of producing wells, it burns the deposited coke, releases hot combustion gases, and converts connate water into steam. The vaporized hydrocarbons and the steam move ahead of the combustion zone, condensing into liquids as they cool and moving oil by miscible displacement and hot waterflooding. Combustion gases provide additional gas drive. Heat lowers the viscosity of the oil, causing it to flow more freely. This method is used to recover heavy, viscous oil. Also called fire flooding.

the taking by an owner of a share of gas or liquids for separate marketing or disposition rather than permitting that share to be disposed of jointly with gas or products belonging to other owners.

a venturi tube that draws foam concentrate into a water stream at a predetermined proportion.

a type of automatic sampling system where the probe and extractor are located directly on the pipeline and the sample is withdrawn from the liquid stream. Compare sample loop.

inch.

inches per second.

square inch.

cubic inch.

an ordinary light bulb.

one-twelfth of a foot-pound and a measure of small amounts of twisting force, or torque. Compare foot-pound (ft-lb).

a scale for measuring small increases or decreases in pressure, usually in conjunction with a manometer, a U-tube containing mercury. Pressure on one side of the U-tube causes the mercury to move upward on the other side. The movement is measured in inches or millimetres. See manometer.

a scale for measuring small increases or decreases in pressure, usually in conjunction with a manometer, a U-tube containing water. Pressure on one side of the U-tube causes the water to move upward on the other side. The movement is measured in inches or millimetres. See manometer.

a written plan that describes the chain of command in an emergency response and designates senior officials and their authority for a given site.

see impending blowout.

see drift angle.

a process to determine the position of an offshore rig or vessel’s center of gravity. A weight having a known value is placed on board the vessel and is moved a measured distance perpendicular to the vessel’s centerline plane. Then, the resulting angle of list is measured to determine the vessel’s center of gravity.

an instrument that measures the angle of a hole.

a person judged by the court to be incapable of managing his or her own affairs by reason of insanity, imbecility, or feeblemindedness (referred to as non compos mentis).

a formation composed of materials that are not bound together. It may produce sand along with hydrocarbons if preventive measures are not taken, or it may slough or cave around the bit or drill stem when a hole is drilled into it.

account maintained by a pipeline that contains the cost subject to pass-through to certain users.

any provision of any contract that provides for the establishment or adjustment of the price for natural gas delivered under such contract by reference to other prices for natural gas, crude oil, or refined petroleum products, or that allows for the establishment or adjustment of the price of natural gas delivered under any contract by negotiation between the parties.

a nonintegrated oil company or an individual whose operations are in the field of petroleum production, excluding transportation, refining, and marketing.

an offshore crane that is constructed in a manner that allows the crane operator to raise and lower the crane boom and to swing (revolve) the crane independently of other crane functions.

see independent.

a person or organization acting independently, but on behalf, of one or more parties involved in the transfer, storage, inventory, or analysis of a commodity or the calibration of land or marine vessels for the purpose of determining the quantity, capacity, and/or quality of a commodity.

functions at only one of several levels in the marketing chain.

an organization of independent oil and gas producers concerned with the relationships between the oil industry and the public and government. Its official publication is Petroleum Independent. Address: 1201 15th Street NW, Suite 300; Washington, DC 20005; 202-857-4722.

often used to mean independent inspector, but usually implying a person or organization capable of total quantity and quality inspection and calibration of shore, truck, rail, and marine vessels, meter proving, and physical properties determinations.

a tank the boundaries of which are not part of the hull structure of a barge.

see independent wire rope core.

a core for wire rope consisting of a strand of steel wires with a spiral winding that is opposite that of the outer strands of the rope. Also called independent wire rope center and king wire.

a fixed or movable part of a measuring instrument’s indicating device (pointer, liquid surface, recording stylus, etc.) the position of which with reference to the scale, indicates the value of the measured quantity.

in a simple gas meter, a shaft that revolves as fluid flows past it; by counting the number of revolutions of the shaft, gas volume can be inferred.

operates on the same principle as an annular valve, except it requires pipe rotation for opening and closing operations.

the sum of crude oil production and imports less changes in crude oil stocks.

the difference between the opening meter reading and the closing meter reading.

the change in meter reading that occurs during receipt or delivery of a liquid product.

the indicated volume multiplied by the meter factor for the particular liquid and operating conditions under which the meter was proved.

a measuring instrument in which the value of the measured quantity is visually indicated but not recorded.

1. a dial gauge used on the rig to measure the hookload. 2. substances in acid-base titrations that, in solution, change color or become colorless as the hydrogen ion concentration reaches a definite value, these values varying with the indicator. In other titrations, such as chloride, hardness, and other determinations, these substances change color at the end of the reaction. Common indicators are phenolphthalein and potassium chromate.

apparatus or equipment in which heat from a primary source, usually the combustion of fuel, is transferred to a fluid or solid, which acts as the heating medium. The substance to be heated does not come into contact with the heat from the primary source. Compare direct heater.

a measurement that produces a final result by calculation using results from one or more direct measurements.

see riser pipe.

the flow of an electric charge, measured in amperes, that is the result of induced voltage. See induced emf.

electromotive (voltage, or electricity) force that is developed in a conductor by moving the conductor within a magnetic field or moving the magnetic field in relation to the conductor.

a fracture in a formation caused by artificial outside forces. The opposite of a natural fracture.

developed in a magnetic material by bringing it into a magnetic field.

see induced emf.

the property of an electric circuit or of two neighboring circuits wherein an electromotive force is generated by induction in one circuit by a change of current in itself or in the other. See induction.

see inductor.

the production of an electric charge, magnetism, or electromotive force in an electric conductor, a magnetizable body, or an electric circuit by the proximity of a similarly energized body or by the variation of the magnetic flux without contact.

see induction survey.

an alternating-current motor in which the primary winding on a part (usually the stator) is connected to a source of power, and the secondary winding (usually on the rotor) carries current induced by the magnetic field of the primary winding.

an electric well log in which the conductivity of the formation rather than the resistivity is measured. Because oil-bearing formations are less conductive of electricity than water-bearing formations, an induction survey, when compared with resistivity readings, can aid in determination of oil and water zones.

see induction survey.

in electronics, the transfer of energy from one circuit to another through the inductance provided by a transformer.

see LC filter.

the retarding effect on the passage of alternating current through a circuit because of inductance. See inductance.

in an electrical circuit, a coil of wire that introduces inductance or magnetic flux into the circuit. It may also react mechanically to changing magnetic flux. Also called electric coil, inductance coil.

hardened, as in indurated steel.

a person who’s area of expertise is protecting and improving the health and well-being of personnel in their work environment.

a group that functions to produce and maintain standards for the industry relating to wellbore survey accuracy. It strives to set standards for terminology and accuracy specifications, establish a standard framework for modeling and validation of tool performance, and raise awareness and understanding of wellbore survey accuracy issues across the industry.

the collision of a neutron and the nucleus of an atom in which the total energy of the neutron is absorbed by the nucleus.

1. the part of a breathing medium, such as helium, that serves as a transport for oxygen and is not used by the body as a life-support agent. Its purpose is to dilute the flow of oxygen to the lungs, thereby preventing oxygen toxicity. 2. in chemistry, gases that have a filled outer electron shell and thus do not easily react with other substances. Examples are helium, argon, neon, and xenon.

the tendency of an object having mass to resist a change in velocity.

a brake that utilizes the energy of a heavy, turning member to actuate the braking action.

1. the process of pressurizing the vapor space of a vessel with an inert gas blanket (usually exhaust gas) to prevent the formation of an explosive mixture. 2. a procedure used to reduce the oxygen content of a vessel’s cargo spaces to 8% or less by volume by introducing an inert gas such as nitrogen or carbon dioxide or a mixture of gases such as flue gas.

a volume meter with the addition of a densitometer from which mass flow is inferred.

drilling wells between known producing wells to exploit the resources of a field to best advantage.

a well drilled between known producing wells to exploit the reservoir better.

a packer with an element that inflates by means of gas or liquid pumped from the surfae through a line. It is deflated by means of slots that can be opened to allow the gas or liquid to flow out. They are used when a temporary packer is needed in a hole with weakened casing that could be damaged by mechanical slips.

consists of two packers spaced exactly as the straddle-packer DST. It is usually set by pump pressure instead of mechanically set.

see feed in.

the relation between the midpoint pressure of the producing reservoir and the liquid inflow rate of a producing well.

a productivity curve plotted when a well has two-phase flow, both oil and gas, based on well tests or a combination of computations and well tests. Also called IPR curve.

an intrusion of formation fluids into the borehole, i.e., a kick.

an MMS document sent to offshore lessees and operators to clarify or supplement operational guidelines.

of or relating to the range of invisible radiation the wavelengths of which range from about 750 nanometers (which is just longer than the color red in the visible spectrum) to 1 millimeter, which borders the region of the spectrum that includes microwaves.

Interstate Natural Gas Association of America.

substances that, on being inhaled, adversely affect health or life.

over­ load or short-circuit protection built into the motor windings.

an acid that has been chemically treated before the acidizing or acid fracture of a well to lessen its corrosive effect on the tubular goods and yet maintain its effectiveness. See acid fracture, acidize.

a drilling fluid to which chemicals have been added to prevent it from causing clay particles in a formation to swell and thus impair the permeability of a productive zone. Salt is a mud inhibitor.

an additive used to retard undesirable chemical action in a product. It is added in small quantities to gasolines to prevent oxidation and gum formation, to lubricating oils to stop color change, and to corrosive environments to decrease corrosive action.

the point at which the mixture starts to boil.

the pressure at which a well that has been closed in on a kick is circulated when well-killing procedures are begun.

see initial gel strength.

the maximum reading (deflection) taken from a direct-reading viscometer after the fluid has been quiescent for 10 seconds. It is reported in pounds/100 square feet. See gel strength.

the early production of an oilwell, recorded after testing operations and recovery of load oil and used as an indicator of the maximum ability of a well to produce on completion without subsequent reservoir damage.

pressure measured at the bottom of a well after it is originally completed and before production starts. Knowing a well’s initial pressure assists reservoir engineers in determining the amount of hydrocarbons in the reservoir.

the point at which a cement slurry begins to harden, or set up, and is no longer pumpable.

in a ship or offshore drilling rig, the condition in which the vessel maintains equilibrium (is stable) when its metacentric height is above its center of gravity.

the permanent lengthening that occurs to new wire rope when it is put into service.

see injection.

the process of forcing fluid into something. For example, in a diesel engine, the introduction of high-pressure fuel oil into the cylinders. In enhanced recovery, the forcing of liquids and gases into an aging reservoir to recover additional hydrocarbons left behind by conventional production methods.

1. a high-pressure gas injected into a formation to maintain or restore reservoir pressure. 2. gas injected in gas-lift operations.

strong steel tubing that conducts fuel from the fuel tanks to fuel injectors on the engine.

a survey used to determine the injection profile, that is, to assign specific volumes or percentages to each of the formations taking fluid in an injection well. The injection log is also used to check for casing or packer leaks, bad cement jobs, and fluid migration between zones.

the spacing and pattern of wells in an improved recovery project, determined from the location of existing wells, reservoir size and shape, the cost of drilling new wells, and the oil recovery expected from various patterns. Common injection patterns include line drive, five spot, seven spot, nine spot, and peripheral.

specific volumes or percentages assigned to each of the intervals in a well that is taking fluid.

a chemical feed pump that injects chemical reagents into a flow-line system to treat emulsions at a rate proportional to that of the flow of the well fluid. Operating power may come from electric motors or from linkage with the walking beam of a pumping well.

the injection of fuel at precisely the right moment in an engine’s operating cycle. Proper injection timing is vital, because it gives maximum power from the fuel, good fuel economy, and clean combustion.

a poppet spring-loaded subsurface valve run in on wireline, landed in a profile, to shut the well in if injection ceases.

water that is introduced into a reservoir to help drive hydrocarbons to a producing well.

a well through which fluids are injected into an underground stratum to increase reservoir pressure and to displace oil. Also called input well.

a fuel atomizing device that injects (puts) a fine spray of fuel into the combustion chamber of an engine.

a control head for injecting coiled tubing into a well that seals off the tubing and makes a pressure-tight connection.

1. on fuel injection systems in engines that do not use a carburetor, a special pump that puts fuel into the engine’s combustion chamber. 2. a chemical feed pump that injects chemical reagents into a flow-line system to treat emulsions at a rate proportional to that of the flow of the well fluid. Operating power may come from electric motors or from linkage with the walking beam of a pumping well.

a floating offshore drilling structure consisting of a barge on which the drilling equipment is constructed. When moved from one location to another, the barge floats. When stationed on the drill site, the barge can be anchored in the floating mode or submerged to rest on the bottom. Typically, inland barge rigs are used to drill wells in marshes, shallow inland bays, and areas where the water is not too deep. Also called swamp barge. See floating offshore drilling rig.

the passage that leads from the air filter to the cylinders of an engine. In a diesel engine, air only is introduced on the intake stroke.

in a vessel or other object, an aperture (opening) through which fluids flow into the vessel or object. For example, in tank system, oil from one tank may flow from the tank’s outlet and into an inlet that opens into another tank.

the height of a liquid in a tank as measured from the bottom (datum plate) of the tank to the liquid surface.

a weight attached to the end of a gauge tape. The tape and bob are used to measure liquid height in a tank. The bob keeps the tape vertical so that an accurate reading can be obtained from the tape.

a measure of the liquid in a tank from the bottom of the tank or a fixed datum plate to the surface of the liquid.

a measure of the liquid height in a tank from the bottom of the tank or datum plate to the top of the liquid.

a method of measuring the height of the liquid in a tank using a pointed gauger’s bob and a graduated tape. In this method, the liquid height is measured from the bottom of the liquid to the top. Compare outage tape-and-bob procedure.

in a bit, the bearings that lie inside of and near the end, or nose, of the cone of a roller cone bit. Typically, the inner bearings include the bearings in the nose of the cone and the bearings near the middle of the cone. These bearings may be a combination of roller, ball, or journal bearings. Compare outer bearings.

a cementing method in which casing is cemented by running drill pipe or tubing to the casing shoe and then pumping the cement down the drill pipe or tubing to the shoe rather than down the casing. The cement exits the shoe and fills the annulus outside the casing as usual.

chemical compounds that do not contain carbon as the principal element (excepting that in the form of carbonates, cyanides, and cyanates). Such compounds make up matter that is not plant or animal.

a petrochemical that does not contain carbon atoms. Inorganic petrochemicals sulfur, ammonia, ammonium sulfate, ammonium nitrate, and nitric acid. Ammonia is a common inorganic petrochemical. See petrochemical.

a functional module of a programmable logic controller that accepts discrete or analog signals from a process.

the transmission shaft for the drawworks that is driven directly by the compounding transmission on a mechanical-drive rig and is connected to it with the master clutch; or, on an electric-drive rig, the shaft driven directly by the electric motors. The input shaft drives the jackshaft or output shaft.

a signal applied to a device, element, or system.

an injection well used for injecting fluids into an underground stratum to increase reservoir pressure.

the heavy current that develops when an induction motor is started at full voltage. It usually decreases gradually as the speed increases and drops sharply when the motor reaches full speed.

1. a cylindrical object, rounded, blunt, or chisel-shaped on one end and usually made of tungsten carbide, that is inserted in the cones of a bit, the cutters of a reamer, or the blades of a stabilizer to form the cutting element of the bit or the reamer or the wear surface of the stabilizer. Also called a compact. 2. a removable part molded to be set into the opening of the master bushing so that various sizes of slips may be accommodated. Also called a bowl. 3. a removable, hard-steel, serrated piece that fits into the jaws of the tongs and firmly grips the body of the drill pipe or drill collars while the tongs are making up or breaking out the pipe. Also called die.

see tungsten carbide bit.

a two-piece steel device with a tapered interior surface that fits into a one-piece or a hinged master bushing. It provides a place in the master bushing for crew members to set the slips. See master bushing, slips.

moorings where wire and/or chain sections are added during a conventional mooring operation.

a sucker rod pump that is run into the well as a complete unit.

any one of several types of valve installed in the drill stem or in a top drive to prevent high-pressure fluids from flowing up the drill stem and into the atmosphere. Also called an internal blowout preventer.

inside blowout preventer.

see internal cutter.

distance across the interior of a circle, especially in the measurement of pipe. See diameter.

solar radiation received at the earth’s surface.

an offshore production platform.

the value of current or voltage at any given instant in a cycle of an AC circuit.

a decentralized public-interest body created by the Mexican government. Its main objective is to carry out research and technological development as required by the petroleum, petrochemical, and chemical industries; to provide technical services for those industries; and to train personnel involved with the Mexican petroleum industry. Address: Apartado Postal 14.805; México, 14, D.F., México.

a device for measuring, and sometimes recording and controlling, the value of a quantity under observation.

in aviation, rules promulgated by the United States Federal Aviation Administration (FAA) that allow an aircraft to be flown in weather conditions that do not meet the minimum requirements for visual flight rules (VFR). In such conditions, pilots control the aircraft by watching the aircraft’s flight instruments and not by looking out the aircraft’s windows. The pilot must have an instrument rating and the aircraft must be equipped and certified for instrument flight. Compare visual flight rules.

a hanger used to lock instruments, such as pressure and temperature bombs, into a seating nipple.

a group that sets standards for instruments made and used in the United States. Its official publications are InTech and Programmable Controls. Address: Box 12277; Research Triangle Park, NC 27709; 919-549-8411; fax 919-549-8288.

used to reduce current or voltage to a known proportion of that in the circuit. A meter is attached to the reduced voltage or current and the voltage or current in the circuit is computed from the meter reading.

a device or assembly of devices designed for one or more of the following functions: to measure operating variables (such as pressure, temperature, rate of flow, and speed of rotation); to indicate these phenomena with visible or audible signals; to record them; to control them within a predetermined range; and to stop operations if the control fails. Simple instrumentation might consist of an indicating pressure gauge only. In a completely automatic system, desired ranges of pressure, temperature, and so on are predetermined and preset.

an electronic device inserted into a pipeline that senses and records irregularities in the line that could be corroded spots. Also called smart pig.

in semiconductors, a transistor that combines low forward voltage drop, gate-controlled turnoff, and high switching speed. It is used in high powered converters.

a flange equipped with plastic pieces to separate its metal parts, thus preventing the flow of electric current. Insulating flanges are often used in cathodic protection systems to prevent electrolytic corrosion and are sometimes installed when a flow line is being attached to a wellhead.

a material with a very low concentration of free electrons that resists the flow of electric current.

for offshore rigs and ships, the condition in which a vessel is in a stable state—that is, the vessel is maintaining equilibrium.

on an engine, a special fitting through which air (and sometimes fuel) enters the engine. On diesel engines, only air enters the intake manifold; on gasoline and other spark-ignition engines, both fuel and air usually enter the manifold.

an opening in a cylinder wall through which gas flows into the cylinder when the intake port is uncovered by the piston.

the downward movement of a piston in a cylinder that creates an area of low pressure inside the cylinder. The low pressure draws in air from the atmosphere (or from a blower).

1. the cam-operated mechanism on an engine through which air and sometimes fuel are admitted to the cylinder. 2. on a mud pump, the valve that opens to allow mud to be drawn into the pump by the pistons moving in the liners.

expense of an item that does not have a salvage value, such as site costs, rig transportation, rig operation, drilling fluid, formation tests, cement, and well supplies.

any positive or negative number including 0.

1. a solution to a differential equation. 2. the sum of variables in a control. 3. the damping effect place in a control system.

in an automatic process control system utilizing feedback, a method that improves performance in regulating the process by gaining control at a faster rate. Also termed proportional plus reset.

in automatic control, the amount of error multiplied by the amount of time the error has been detected, which determines the severity of the problem. Process system operators use integral gain as a multiplier to give them control over how aggressive he wants this control to correct the problem.

tank the boundaries of which are the bottom, side, deck, or bulkhead of the barge hull.

an interconnected arrangement of active and passive electronic elements incorporated (integrated) with a single semiconductor substrate or deposited on the substrate by a continuous series of compatible processes, and capable of performing at least one complete electronic circuit function.

in the petroleum industry, a company that is engaged in all phases of the oil business, from production, to transportation, refining, and marketing. An integrated oil company controls its own oil from the wellhead to the gasoline pump.

a process in which coal is gasified (turned into gas). The resulting gas is termed syngas, which combines the words synthesis and gas. The process removes impurities from the syngas before it is burned as a fuel and converts pollutants into useful products. Excess heat generated by the process is sent to a steam turbine, which is called a combined cycle gas turbine.

an operational amplifier with a feedback, or shunt, capacitor in which the waveform at the output is the integral (usually over time) of the input.

a circuit or network whose output waveform is the time integral of its input waveform. Also known as integrator.

an orifice meter with an automatic integrating device. It is constructed so that the product of the square roots of the differential and static pressures is recorded on the chart. The products are continuously totaled and shown on a counter index. When the product total is multiplied by the orifice flow constant, the rate of flow is determined directly.

see watthour meter.

the department of an oil and gas company that receives orifice meter charts and integrates, or averages, the static and differential pressure readings recorded on the chart. Today, computerized measurement techniques have all but eliminated the need for such a department.

a computer device that approximates the mathematical process of integration. See integrating network.

the quality of language that is comprehensible.

a pressure-multiplier-type well servicing mobile pump.

see isolation valve.

pertaining to real estate, a right or a claim to property.

1. the contact surface between two boundaries of liquids (e.g., the surface between water and the oil floating on it). 2. a means for coupling unlike equipment or functions so that they may communicate and work in unison.

a device that buffers, isolates, or changes the character of control signals in an automatic controller.

the surface tension occurring at the interface between two liquids that do not mix, such as oil and water. Interfacial tension is caused by the difference in fluid pressures of the liquids.

the distance that the ends of one bit cone extend into the grooves of an adjacent one in a roller cone bit. Also called intermesh.

an international organization that regulates maritime practices, including possible pollution of the oceans by tanker-cleaning effluent. Later became International Maritime Organization.

automatic process by which an operation cannot be initiated until certain requirements have been met.

Office of International Activities and Marine Minerals (MMS).

the string of casing set in a well after the surface casing but before production casing is set to keep the hole from caving and to seal off troublesome formations. In deep wells, one or more intermediate strings may be required. Sometimes called protection casing.

a system of gears that transmits rotary motion.

see intermediate casing string.

see interfit.

a pipeline sample withdrawn by equal increments at a rate of less than one increment per minute.

a sampler that transfers equal increments of oil from a pipeline to the sample container at a uniform rate.

see gas lift.

a regulation device used in production of a flowing well. The well flows wide open (or through a choke) for short periods several times a day and is then closed in. Also used in some gas-lift installations.

also called inside blowout preventer. See inside blowout preventer.

a fishing tool containing metal-cutting knives that is lowered into the inside of a length of pipe stuck in the hole to cut the pipe. The severed portion of the pipe can then be returned to the surface. Compare external cutter.

distance across the interior of a circle, especially in the measurement of pipe. Also called inside diameter.

energy possessed by a body by reason of its molecular forces, independent of its potential or kinetic energy. A match or explosive has internal energy.

an alignment clamp used on the inside of pipe. It uses a number of small expandable blocks, or shoes, to grip the inside surfaces of both pipe joints and hold them in place. The clamp can also act as a swab to clean the inside of the pipe. Compare external line-up clamp.

the fluid droplets or solids that are dispersed throughout another liquid in an emulsion. Compare continuous phase.

see inside blowout preventer.

an extra-thick inside wall on the end of tubing or drill pipe at the point where it is threaded to compensate for the metal removed in threading. Unlike external upset drill pipe, which has the extra thickness on the outside, drill pipe with internal upset has the extra thickness inside and a uniform, straight wall outside. Compare external upset end, internal-external upset end.

a heat engine in which the pressure necessary to produce motion of the mechanism results from the ignition or burning of a fuel-air mixture within the engine cylinder.

on tubing, casing, or drill pipe, the thickening at each end of the joint such that the internal diameter and the external diameter of the joint increase in thickness at each end. Compare external upset end, internal upset end.

see internal upset end.

an organization formed in 1968 and headquartered in London, England, it is dedicated to safe ships and clean seas. IACS provides technical support, compliance verification, and research and development in the interests of maritime safety and regulation. IACS’s classification design, construction, and through-life compliance rules and standards cover more than 90% of the world’s cargo carrying tonnage. Address: 5, Old Queen Street, London, SW1H 9JA, UK; www.iacs.org.uk.

an organization of drilling contractors that sponsors or conducts research on education, accident prevention, drilling technology, and other matters of interest to drilling contractors and their employees. Its official publication is The Drilling Contractor. Address: 10370 Richmond Ave. Suite 760; Houston, TX 77042; 713-292-1945; fax 713-292-1946.

see safety of life at sea rules.

an agency of the United Nations that provides an international forum for nations to discuss international cooperative efforts to improve marine safety and to protect the ocean environment. International treaties on safety (SOLAS) and environmental protection (MARPOL) have been negotiated at IMO. The governing body of the IMO is the Assembly, which meets once every two years and is open to all 136 member states (countries). IMO is headquartered in London. Address: 4 Albert Embankment; London SE 1 75R; 71 7357611.

a standard recognized by an international agreement to serve as the basis for fixing the value of all other standards of the given quantity.

a system of units of measurement based on the metric system, adopted and described by the Eleventh General Conference on Weights and Measures. It provides an international standard of measurement to be followed when certain customary units, both U.S. and metric, are eventually phased out of international trade operations. The symbol SI (Le Système International d’Unités) designates the system, which involves seven base units: (1) metre for length, (2) kilogram for mass, (3) second for time, (4) Celsius for temperature, (5) ampere for electric current, (6) candela for luminous intensity, and (7) mole for amount of substance. From these units, others are derived without introducing numerical factors.

variations in meter pulse width/space, normally expressed as a percentage.

equipment to cool the gas between the stages of compression, which removes the heat of compression.

a federal agency that until 1977 had jurisdiction over oil pipelines engaged in interstate commerce. See Federal Energy Regulatory Commission.

gas that travels across state lines.

an association of gas trans­ mission companies, producers, and distributors. Address: 10 G Street NE, Suite 700; Washington, DC 20002; 202-216-5900.

a commission that comprises governors of oil-producing states. It works cooperatively with the EPA to assist states in improving regulatory programs. Address: P. O. Box 53127; Oklahoma City, OK 73152-3127; 405-525-3556.

a natural gas pipeline company that is engaged in the transportation, by pipeline, of natural gas across state boundaries. The pipeline is subject to FERC jurisdiction under the Natural Gas Act and under the Natural Gas Policy Act.

a pore space in a reservoir rock.

water contained in the interstices, or pores, of reservoir rock. In reservoir engineering, it is synonymous with connate water. Compare connate water.

the low-pressure frontal zone that serves as the dividing line between the northeast and southeast trade winds.

without leaving a will. A person may be said to have died intestate.

gas that does not cross state lines as it is piped from producer to consumer.

a natural gas pipeline company that is engaged in the transportation, by pipeline, of natural gas not subject to FERC jurisdiction under the Natural Gas Act and under the Natural Gas Policy Act.

a phrase applied to operations that are necessary and uniquely associated with oil and gas exploration and production operations. In order to be intrinsic and unique to E&P operations, they must be associated with efforts to locate oil or gas deposits; to remove oil or natural gas from the ground; or to remove impurities from substances as an integral part of primary field operations.

an igneous rock that, while molten, penetrated into or between other rocks and solidified.

an area within a permeable rock adjacent to a wellbore into which a filtrate (usually water) from the drilling mud has passed, with consequent partial or total displacement of the fluids originally present in the zone.

a proprietary low-expansion metal alloy consisting of 36 percent nickel, 0.35 percent manganese, and 63.65 percent iron that contains a minimum of carbon and other elements; used for watch parts and the measuring guides of accurate instruments.

a water-in-oil emulsion in which fresh or salt water is the dispersed phase and diesel, crude, or some other oil is the continuous phase. Water increases the viscosity and oil reduces the viscosity.

an oil mud in which fresh or salt water is the dispersed phase and diesel, crude, or some other oil is the continuous phase. See oil mud.

see invert-emulsion mud.

an electronic device that converts direct current into alternating current.

a logic circuit (also called a NOT circuit) with one input and one output that inverts the input signal at the output—that is, the output signal is a logical 1 if the input signal is a logical 0 and vice versa.

in an operational amplifier, a type of input wherein if the input signal is changed, the output is also changed. For example, if the inverting input increases in voltage, the output voltage inverts, or decreases. Also called minus input. Compare noninverting input.

in economics, the commitment of money (capital) to purchase financial instruments or other assets so as to gain profitable returns in the form of interest, income, or appreciation of the value of the instrument or asset.

the number indicating the amount of iodine absorbed by oils, fats, and waxes, giving a measure of the unsaturated linkages present. Generally, the higher the iodine number, the more severe the action of the oil on rubber.

Interstate Oil and Gas Compact Commission.

an atom or a group of atoms charged either positively (a cation) or negatively (an anion) as a result of losing or gaining electrons.

the process by which a neutral atom becomes positively or negatively charged through the loss or gain of electrons.

to give a neutral atom either a positive or negative charge; after being ionized, the neutral atom becomes an ion. See ion.

Independent Petroleum Association of America.

inflow performance relationship.

see inflow performance relationship curve.

improved plough (plow) steel.

infrared.

voltage drop, as determined by the formula E = IR.

1. a heavy, magnetic, malleable, and ductile element occurring in the earth’s crust in many types of ores. 2. a loose term used in the oilfield for any tool or device generally made of metal, whether it contains iron or not.

a measure of iron compounds in the product stream, determined by chemical analysis, which reflects the occurrence and the extent of corrosion.

see ferrous oxide.

see pyrite.

a manufacturer’s name for a floor-mounted combination of a spinning wrench and a torque wrench. The Iron Roughneck moves into position hydraulically and eliminates the manual handling involved with suspended individual tools.

a method for removing small concentrations of hydrogen sulfide from natural gas by passing the gas over a bed of wood shavings that have been impregnated with a form of iron oxide (iron sponge). The hydrogen sulfide reacts with the iron oxide, forming iron sulfide and water.

see ferrous sulfide.

in a coil of wire that carries electric current, the placement of a length of soft iron in the central interior part of the coil.

Instrument Society of America.

Industry Steering Committee on Wellbore Survey Accuracy.

a combining form meaning equal; used to form compound words, such as isobutane.

a line drawn on a weather map connecting points of equal atmospheric pressure.

is an alkane, otherwise referred to as an isomeric with butane. It is the simplest alkane with a tertiary carbon, also known as methoylpropane or 2-methylpropane. Isobutane is a hydrocarbon of the paraffin series with the formula C4H10 and having its carbon atoms branched.

a contour map that shows the thickness of a pay section in a reservoir. Used for estimating reservoir content. See contour map.

a short-time back-pressure test for low-permeability reservoirs that otherwise require excessively long times for pressure stabilization when wells are shut in.

a governor that maintains a constant speed of the prime mover regardless of the load applied, within the capacity of the prime mover.

a map that shows the isogonic lines joining points of magnetic declination, which is the variation between magnetic north and true north. For example, in Los Angeles, California, when the compass needle is pointing toward north, true north actually lies 15° east of magnetic north. See declination.

an imaginary line on a map that joins places on the earth’s surface at which the variation of a magnetic compass needle from true north is the same. This variation, which may range from 0 to 30 or more degrees either east or west of true north, must be compensated for to obtain an accurate reading of direction.

a sample taken from a pipeline in which the linear velocity of the fluid through the opening of the sample probe is equal to the linear velocity in the pipeline and is in the same direction as the bulk of the fluid in the pipeline approaching the probe.

to pack off above and below a zone of interest.

a special blocking device (a plug) that is used in pressure testing a blowout preventer. The plug is run and landed in a high-pressure wellhead housing, where it forms a pressure-tight seal. This seal protects (isolates) the casing below the wellhead from the high pressures used to test the blowout preventers, which are located above the wellhead and casing.

a special downhole valve installed in the tubing string that is used to protect the formation from the well’s hydrostatic pressure after a gravel pack. The valve has a flapper, which closes and can then be broken out. An isolation valve protects the reservoir from hydrostatic pressure during gravel packing.

a map of a formation on which points of similar lithology are connected by a series of contours.

in chemistry, any of two or more substances composed of the same elements in the same proportions but, because the atoms are arranged differently in each element, they have different properties.

in petroleum refining, the process of altering the fundamental arrangement of the atoms in the molecule without adding or removing anything from the original material. Straight-chain hydrocarbons are converted to branched-chain hydrocarbons with a substantially higher octane rating in the presence of a catalyst at moderate temperatures and pressures. The process is basic to the conversion of normal butene into isobutane.

a drawing of a three-dimensional object in which lines parallel to the edges are drawn to scale without perspective or foreshortening.

a geological map of subsurface strata showing the various thicknesses of a given formation as a series of contours. It is widely used in calculating reserves and in planning improved recovery projects.

a contour line drawn on a map joining points of equal thickness in a stratigraphic unit.

a material that irritates the skin very little and that is used as an odorless solvent, reaction diluent, and in some proprietary formulations.

equilibrium between large segments of the earth’s crust, which float on the denser mantle in such a way that thicker segments extend higher and deeper than thinner segments, and lighter blocks rise higher than denser blocks.

constant temperature curve.

the compression of air or gas that exists when the interchange of heat between the air or gas and surrounding bodies (i.e., cylinders or pistons) takes place at a rate exactly sufficient to maintain the air or gas at constant temperature as the pressure increases.

a form of an element that has the same atomic number as its other forms but has a different atomic mass. Isotopes of an element have the same number of protons but different numbers of neutrons in the nucleus.

intertropical convergence zone.

Information to Lessees and Operators.

internal upset end.

independent wire rope core.