Glossary

newton.

in a semiconductor material such as silicon, the arrangement of atoms in the material in such a manner that electron flow occurs between the atoms and thus creates a negative charge. Compare p-type structure.

nitrogen.

National Ambient Air Quality Standards.

National Association of Corrosion Engineers.

a pin shaped like a carpenter’s nail and placed in a pressure relief valve. When the pin shears, it opens the valve to relieve pressure inside a vessel. Even though a nail pin is shaped like a nail, a carpenter’s nail should never be substituted for a nail pin. See shear pin.

National Association of Maritime Educators.

a logic circuit whose output signal is a logical 1 if all of its inputs is a logical 0, and whose output signal is a logical 0 if all of its inputs are a logical 1.

one-billionth (10–9) of a farad. See farad.

a special soap made up of aluminum soaps and/or various kinds of fatty acids that, when mixed with gasoline, makes a firm jelly.

a volatile, flammable liquid hydrocarbon distilled from petroleum and used as a solvent or a fuel.

see naphthene series.

the saturated hydrocarbon compounds of the general formula CnH2n (e.g., ethene or ethylene, C2H4). They are cycloparaffin derivatives of cyclopentane (C5H10) or cyclohexane (C6H12) found in crude petroleum.

a crude oil that is characterized by a low API gravity and a low yield of lubricating oils and that has a low pour point and a low viscosity index (compared to paraffin-base oils). It is often called asphalt-base oil, because the residue from its distillation contains asphaltic materials but little or no paraffin wax.

a large body of rock that has been thrust horizontally over neighboring rocks by compressive forces, as during the collision of two continents.

standards listed under the CAA for six major, or criteria, pollutants: ozone, carbon monoxide, sulfur dioxide, lead, nitrogen dioxide, and particulate matter. Areas that exceed the recommended levels for these pollutants are nonattainment areas, or areas with poor air quality; areas that meet or fall below the NAAQS levels are attainment areas, or areas with good air quality.

organization whose function is to establish standards and recommended practices for the field of corrosion control. Its publications are Corrosion, Corrosion Abstracts, and Materials Performance. Address: P.O. Box 201009; Houston, TX 77216-1009; 281-228-6200; Fax (281) 228-6300.

Address: 124 N. Van Ave.; Houma, LA 70363-5895; 985-879-3866.

a document sponsored by the National Fire Protection Agency (NFPA), the National Electric Code (NEC) establishes standards for safe electrical installations. Electricians, electrical contractors, engineers, and inspectors use the NEC as a guide when installing electrical wiring. Most cities and other authorities in the U.S. require that houses, buildings, factories, etc., be wired to meet NEC standards.

an organization created in 1926 by the merger of the Electric Power Club and the Associated Manufacturers of Electrical Supplies. NEMA provides a forum for the standardization of electrical equipment to ensure the manufacture of safe, effective, and compatible electrical products. NEMA also makes contributions to the electrical industry by shaping public policy development and operating as a central confidential agency for gathering, compiling, and analyzing market statistics and economics data. Address: 1300 North 17th Street, Suite 1752, Rosslyn, VA 22209; 703-841-3200; www.nema.org.

emissions standards set forth under CAA for airborne pollutants that are immediately hazardous to human health or that cause cancer, gene mutation, or reproductive harm.

a congressional act that forms the basic national charter for protection of the environment. Ensures that no agency of the federal government will take action that will significantly affect the quality of the human environment.

founded in 1896, an organization that provides fire, electrical, and life safety to the public. The mission of the international nonprofit NFPA is to reduce the worldwide burden of fire and other hazards on the quality of life by providing and advocating scientifically-based consensus codes and standards, research, training, and education. Address: 1 Batterymarch Park, Quincy, MA 02169; www.nfpa.org.

congressional act that provides for the development of a National Artificial Reef Plan to promote and facilitate responsible and effective efforts to establish artificial reefs.

congressional act that provides for the protection of historic and prehistoric archaeological resources.

an organization established by the OSH Act within the Department of Health, Education and Welfare to develop and establish recommended occupational safety and health standards and to conduct research. The OSH Act requires NIOSH to publish an annual listing of all known toxic substances and the concentrations at which such toxicity is known to occur.

part of the National Oceanic and Atmospheric Administration (NOAA), NOS measures and predicts coastal and ocean phenomena, protects large areas of the oceans, and works to ensure safe navigation. Web site address: www.nos.noaa.gov.

an agency of the U.S. Department of Commerce that establishes national policies for and manages and conserves our oceanic, coastal, and atmospheric resources and applies its managerial, research, and technical expertise to provide practical services and essential scientific information. Address: Department of Commerce, 14th & Constitution Avenue NW; Washington, DC 20230; 301-713-4000.

an oil company owned by a country—that is, the company is not privately owned—that explores for, drills for, and produces oil and natural gas. Moreover, a national oil company almost always owns the mineral rights to the land or water under which oil and gas are found and produced.

a service under the DOI that has the responsibility of forming, overseeing, maintaining, and developing national parks and monuments. The National Park Service was also made protector of the nation’s historic and natural heritage with the Water Conservation Act, the Wilderness Act (1964), the Historic Preservation Act (1966), and the Wild and Scenic Rivers Act (1968). Address: 1849 C St. NW; Washington, DC 20240; 202-208-3818.

a permit system set up under the CWA and implemented by qualified state governments to regulate pollutant discharges. NPDES permits specify the types of control equipment required and the discharges allowed for each facility. The permits specify levels of performance, and failure to achieve these levels must be reported. All permits can be reviewed by the EPA, the Army Corps of Engineers, and the Fish and Wildlife Service.

the USCG headquarters for emergency incidents. The NRC is operated 24 hours a day by the USCG in cooperation with 14 other federal agencies. Whenever a hazardous material release occurs in American waters, it must be reported to the NRC under federal law. Address: 2100 2nd Street, Room 2611; Washington, DC 20593; 800-424-8802.

a standard recognized by an official national decision as the basis for fixing the value, in a country, of all other standards of the given quantity. In general, the national standard in a country is also the primary standard.

the USCG national response system headquartered in Elizabeth City, North Carolina. The NSFCC is charged with maintaining a comprehensive list of spill removal resources, personnel, and equipment that is available worldwide and to make that list available to federal and state agencies and the public. The ­NSFCC provides technical assistance, equipment, and other resources required by the federal on-scene coordinator; coordinates the use of private and public personnel and equipment to remove a worst-case discharge and mitigate or prevent a substantial threat of such discharge; administers the coast guard strike teams; and provides technical assistance in preparing area contingency plans. The NSFCC maintains on file all area contingency plans and is required to review each of those plans that affects its responsibility. Address: 1461 North Road St.; Elizabeth City, NC 27909; 252-331-6006.

an office of the National Oceanic and Atmospheric Administration that provides weather information and warnings to every county, parish, and major metropolitan area in the country. Address: 1325 East-West Highway; Silver Spring, MD 20910; (301) 713-0622. Regional office: 819 Taylor St.; Fort Worth, TX 76102; 817-978-1111, ext. 140.

see formation gas.

see naturally aspirated.

clays that are encountered when drilling various formations; they may or may not be incorporated purposely into the mud system.

see reservoir drive mechanism.

a highly compressible, highly expansible mixture of hydrocarbons with a low specific gravity and occurring naturally in a gaseous form. Besides hydrocarbon gases, natural gas may contain appreciable quantities of nitrogen, helium, carbon dioxide, hydrogen sulfide, and water vapor. Although gaseous at normal temperatures and pressures, the gases making up the mixture that is natural gas are variable in form and may be found either as gases or as liquids under suitable conditions of temperature and pressure.

those hydrocarbons liquefied at the surface in field facilities or in gas processing plants. Natural gas liquids include propane, butane, and natural gasoline.

see natural gas processing plant.

a congressional act started to deregulate the price charged by producers for “new” gas—gas discovered since 1977—at the wellhead. This act was designed to achieve deregulation gradually, with the total release of price controls effective January 1, 1985.

an installation in which natural gas is processed for recovery of natural gas liquids, the heavier hydrocarbon components of natural gas, including liquefied petroleum gases (such as butane and propane), and natural gasoline.

see compressor station.

the liquid hydrocarbons recovered from wet natural gas, i.e., casinghead gasoline.

a metallic ore, such as magnetite, that has a natural magnetism.

a drilling fluid containing essentially clay and water; no special or expensive chemicals or conditioners are added. Also called conventional mud.

in a ship or offshore floating rig, the duration of one free oscillation of the vessel caused by the effects of wind, waves, and currents on the vessel.

the time required for a ship or floating offshore drilling rig to roll from one side to the other and back one time.

term used to describe an internal combustion engine in which air flows into the engine by means of atmospheric pressure only. Compare supercharge.

an engine in which the air enters the engine’s cylinders by the simple action of the pistons moving downward in the cylinders. Compare supercharged engine.

found in nature or occurring naturally without the aid of a chemical process.

alternate term for naturally occurring radioactive materials (NORM). See naturally occurring radioactive materials (NORM).

radioactive materials that occur naturally and that are brought to the surface during drilling operations or that contaminate drilling fluids, pipe scale, soil, or equipment. Although the EPA regulates NORM only in fertilizer (as of June 1992), it is likely that the regulation of other NORM material will follow in the near future. Currently, only Louisiana has state NORM regulations, but many other states are in the process of initiating regulations or have expressed an interest in doing so.

a unit of length used in sea and air navigation that is based on the length of 1 minute of arc of a great circle, especially an international and U.S. unit equal to 1,852 metres (about 6,076 feet).

a person who designs ships, barges, offshore rigs, and other vessels that operate in the water.

the study of the physical characteristics and the design and construction of buoyant structures, such as ships, boats, barges, submarines, offshore rigs and floats that operate in water. The discipline also includes the construction and operation of power plants and other mechanical equipment of the structures.

part of the United States Navy, this office maintains a fleet of survey vessels that collect data from all parts of the world. Once the data is collected, NAVOCEANO analyzes it and provides information for the military as well as civilian interests. Address: 1100 Balch Boulevard, Stennis Space Center, MS 39529; (228) 688-3344; www.ssc.nasa.gov.

any waters that are deep enough and wide enough to support a ship. The term has been broadly defined in recent years to include any waters that can float a canoe. Under this definition, drainage ditches, gullies, and small sinks can temporarily become navigable when it rains and thus may be defined as navigable even when dry.

(pronounced “nav-oci-ano”) Naval Oceanographic Office.

nondestructive testing.

a tide that has the smallest range between high and low tide at a given location. This type of tide occurs when the sun and moon lie at right angles to each other (during first and third quarters).

in marketing, the next three years.

drilling in which the hydrostatic head of the fluid column in the wellbore is in balance with, or only slightly greater than, formation pressure. Near-balance, or low-head drilling, when properly applied, does not allow hydrocarbons or other formation fluids to enter the wellbore.

a cement with no additives other than water.

National Electric Code.

to taper to a reduced diameter. A pipe becomes necked down when it is subjected to excessive longitudinal stress.

the tendency of a metal bar or pipe to taper to a reduced diameter at some point when subjected to excessive longitudinal stress. See bottleneck.

a device that controls the rate of flow in a line (a valve), which contains a sharp-pointed, needlelike plug that is driven into and out of a cone-shaped seat to control accurately a relatively small rate of fluid flow.

a phenomenon that occurs at the atomic level of elements whereby the element has a surplus of electrons—that is, it has a lower electric potential. Compare positive charge.

see negative state.

1. in process control, an arrangement wherein a portion of the output of a circuit, device, or machine is fed back 180° out of phase with the input signal. Negative feedback decreases amplification to stabilize it with respect to time or frequency. Decreased amplification reduces distortion and noise. Also known as inverse feedback, reverse feedback, and stabilized feedback. See feedback. 2. the return of a portion of the output current of a circuit to its input (feedback) in which the portion returned is 180 degrees out of phase with the input signal. This out-of-phase feedback decreases the amount of amplification in the circuit and stabilizes it with respect to time or frequency. Negative feedback reduces distortion and noise in the amplifier.

on the record made by a gravity survey, salt domes are less dense than the overlying sedimentary rocks, which may indicate a negative gravity anomaly

in a ship or floating offshore rig. the condition that occurs when the vessel’s metacenter is below the vessel’s center of gravity. In a negative state, the vessel is not stable and can capsize. See center of gravity, metacenter.

the terminal of a battery or other voltage source away from which electrons flow and toward which holes flow. See holes, terminal.

National Electrical Manufacturers Association.

a synthetic rubber made by the polymerization of chloroprene; it resists being broken down when exposed to various chemicals and oil. Neoprene can be used for an annular preventer’s packing element when oil-based muds are being used at temperatures ranging from –30°F to 170°F.

National Environmental Policy Act.

National Emissions Standards for Hazardous Airborne Pollutants.

a term applied to grated deck flooring on offshore installations that refers to the area of the flooring that does not include areas of grating that are removed to clear obstructions or to allow pipe, ducts, columns, and the like to pass through the grating. Compare gross area.

the difference between the gross heating value and the heat energy required to vaporize water trapped in the gas. Also called low heating value.

the amount of money a business makes after total revenue and gains are added and all expenses and losses are subtracted.

the total volume of all petroleum liquids, excluding S&W and free water, at observed temperature and pressure.

the amount of oil produced by a well or a lease, exclusive of its S&W content. Net production is also called working-interest oil (i.e., the oil produced by all of its wells multiplied by the working interest of a company in the wells).

a lease agreement in which the lessor shares in the net proceeds of production after the lessee has recovered the initial investment. The various expenses allowed as deductions from gross proceeds are points of negotiation. Also applies to working-interest relationships.

the volume of the interior of a ship measured in tons (100 cubic feet or 2.83 cubic metres), excluding the space occupied by fuel, the engine room, navigation equipment, and the crew quarters.

the portion of oil and gas production money out of which operating and development costs are paid (i.e., the portion remaining after deduction of royalty interests).

the total volume of all petroleum liquids, excluding S&W and free water, corrected by the appropriate temperature correction factor (Ctl) for the observed temperature and API gravity, relative density, or density to a standard temperature such as 60°F or 15°C, and also corrected by the applicable pressure correction factor (Cpl) and meter factor.

the total weight of all petroleum liquids, excluding S&W and free water, determined by applying the appropriate weight conversion factor to the net standard volume.

the indicated volume corrected for meter errors, for volume differences due to metering pressure and temperature differing from reference conditions, and for S&W content, where applicable.

the gross tonnage of a ship or a mobile offshore drilling rig less all spaces that are not or cannot be used for carrying cargo, expressed in tons equal to 100 cubic feet.

the total volume of liquid in a tank after adjustments have been included for S&W content, temperature, and density. Compare gross volume.

the share of production remaining to the working-interest owners after all royalties, overriding royalties, production payments, and other reservations or assignments have been deducted.

a system of electronic and mechanical devices that automatically determines the amount of oil in a water and oil emulsion. The water and oil do not have to be separated to measure the volume of the oil.

the amount, or volume, of oil in the produced fluids of a well or wells, usually as measured by a net-oil computer.

1. position of the rig’s weight indicator where hook load is zero. 2. position of an engine’s transmission when the engine’s flywheel or other power transmission device is not being turned by the engine. 3. of or relating to a particle, an object, or a system that has neither a positive nor a negative electric charge; of or relating to a particle, object, or system that has a net electric charge of zero.

the condition when the righting arm is zero and consequently the righting couple is zero. See neutral state.

a weather phenomenon formed when a cold front overtakes a warm or stationary front and occurs when the temperature of the cold and warm air masses are virtually the same. Compare cold occlusion, warm occlusion.

a packer that, unlike compression or tension packers, requires neither set-down weight nor upstrain pull to remain set.

in a ship or floating offshore drilling rig, the condition that occurs when the vessel’s metacenter and center of gravity are in the same position. In the neutral state, the vessel is not as stable as it is when it is in a positive state. See center of gravity, metacenter, positive state.

a reaction in which the hydrogen ion of an acid and the hydroxyl ion of a base unite to form water, the other ionic product being salt.

a neutral particle ejected from the nucleus of an atom when the neutron-to-proton ratio is too high. Neutrinos are difficult to dentect, because of their penetrating power, and are not recorded in logging.

an electrically neutral subatomic particle in the nucleus of an atom, whose mass is about 1,845 times that of the electron. A neutron is stable when bound in an atomic nucleus. It and the proton form nearly the entire mass of atomic nuclei. A part of the nucleus of all atoms except hydrogen. Under certain conditions, neutrons can be emitted from a substance when its nucleus is penetrated by gamma particles from a highly radioactive source. This phenomenon is used in neutron logging.

a pulsed-neutron survey.

a radioactivity well log used to determine formation porosity. The logging tool bombards the formation with neutrons. When the neutrons strike hydrogen atoms in water or oil, gamma rays are released. Since water or oil exists only in pore spaces, a measurement of the gamma rays indicates formation porosity. See radioactivity well logging.

radiation produced by nuclear disintegration, as when a nucleus is penetrated by gamma rays from a highly radioactive source. Neutron radiation can penetrate several feet of lead and is so difficult to observe that it remained undiscovered long after alpha, beta, and gamma rays were well known.

CAA standards that set forth allowable emissions for new major pollution sources and major modifications to existing sources. NSPS can extend to pollutants not included in NAAQS and NESHAP and may include VOCs and hydrogen sulfide.

an SI unit that expresses force. One newton equals 1 metre-kilogram per second per second (m•kg/s2), which is the force required to move 1 kilogram a distance of 1 metre at a velocity of 1 second squared.

see joule.

see Newtonian fluid.

a fluid in which the viscosity remains constant for all rates of shear if constant conditions of temperature and pressure are maintained. Most drilling fluids behave as non-Newtonian fluids, as their viscosity is not constant but varies with the rate of shear.

a fuel made from grass or microorganisms such as algae.

nanofarad.

National Fire Protection Association.

natural gas liquids.

natural gas pricing categories created by the Natural Gas Policy Act. The NGPA divides all natural gas into a large number of sections, each subject to different maximum lawful pricing rules.

nickel.

the trademarked name of a nickel-chromium alloy that has high electrical resistance and the ability to withstand high temperatures; it is often used as the elements in electric heaters.

a silver-gray, ductile, malleable, and tough metal used in alloys, plating, coins, ceramics, and electronic circuits.

a general feeling of itchiness or sensation of skin irritation related to decompression sickness.

an assistant toolpusher whose duty hours are typically during nighttime hours on a mobile offshore drilling unit.

a dark gray, thick, low-level cloud that is composed of water droplets.

National Institute for Occupational Safety and Health.

a tubular pipe fitting threaded on both ends and less than 12 inches (30 centimetres) long, used for making connections between pipe joints and other tools.

(slang) a crew member who procures and delivers tools and equipment for a drilling rig.

in drilling, to assemble the blowout preventer stack on the wellhead at the surface.

National Institute of Standards and Technology.

: to combine with nitrogen.

a synthetic rubber formed by polymerization of acrylonitrile with butadiene. Nitrile rubber can be used as a packing element in an annular preventer where oil-based mud is being used at temperatures ranging from 30°F to 180°F.

a formation-stimulation process first used about a hundred years ago in Pennsylvania. Nitroglycerine is placed in a well and exploded to fracture the rock. Sand and gravel or cement is usually placed above the explosive charge to improve the efficiency of the shot. Nitro shooting has been largely replaced by formation fracturing.

a colorless inert gas used in underbalanced drilling. Although more expensive than air or natural gas, because it is inert, it does not promote corrosion and can therefore save money in corrosion costs.

a reddish-brown gas sometimes used in workover operations to clean out (jet) a well.

the intoxicating or narcotic effect of gaseous nitrogen experienced by a diver breathing air at greater than 100 feet (30.5 metres) of depth. The effect increases with depth, impairing a diver’s ability to think and act effectively.

in blowout preventer closing systems (accumulators), the pressure, usually at 1,000 pounds per square inch or 6,895 kilopascals, placed inside an accumulator bottle by injecting nitrogen gas into the bottle. Usually, a flexible bladder inside the bottle separates the nitrogen from the operating fluid that is used to open and close the blowout preventers. Separating the two fluids prevents nitrogen from dissolving in the hydraulic operating fluid. See accumulator (def. 2).

a process used to remove nitrogen from natural gas to maintain a desired Btu value for marketing. See British thermal unit.

equipment in which nitrogen is removed from feed gas.

National LP-Gas Association.

nonmagnetic drill collar.

diving which involves depths and times shallow and short enough so that the ascent can be made to the surface without water stops or subsequent chamber decompression.

a device of a known and precise dimension that is lowered into a well to determine the dimensions of another device or opening already in the well.

a special nipple made up in the tubing, casing, or drill pipe string the configuration of which is such that a tool contacting it can pass through only if the tool is in the proper position or configuration.

in a transformer, losses in electrical energy that occur in the primary, secondary, and core of the transformer; no-load losses occur whether or not the transformer is loaded.

nitrogen dioxide.

(pronounced “noah”) National Oceanic and Atmospheric Administration.

a nationwide network of radio stations broadcasting continuous weather information from a nearby National Weather Service (NWS) office. NWR broadcasts NWS warnings, watches, forecasts, and other information 24 hours a day. NWR includes more than 800 transmitters, covering all 50 states, coastal waters, Puerto Rico, the U.S. Virgin Islands, and the U.S. Pacific Territories. NWR requires a special radio receiver or scanner capable of picking up the signal. Broadcasts occur at seven radio frequencies: 162.400 megahertz (MHz), 162.425 MHz, 162.450 MHz, 162.475 MHz, 162.500 MHz, 162.525 MHz, and 162.550 MHz.

any of the metals with low reactive tendencies at the upper end of the electrochemical series.

1. in electronic circuits an unwanted component of a signal that obscures the content of the signal’s information. 2. any spurious voltage or current arising from external sources and appearing in the circuits of a device.

a designated size that is very close to, but that may be different from, the actual size.

wire rope strength that the manufacturer calculates using a standard procedure established by the wire rope industry. Also called catalog strength. Compare breaking strength, minimum acceptance strength.

the quantity assigned to a tank or vessel for the purpose of identification only; the exact volume may be somewhat different from the nominal volume.

the amount of oil or gas a purchaser expects to take from a field as reported to a state regulatory agency.

a chart that presents an equation containing a number of variables in the form of several straight lines. The straight lines are scaled with values of the variables. To use it, a straight edge is placed across the scaled lines at the appropriate values. A nomograph can be easier to use than solving the equation.

a supervisor that must never dive or enter the chamber.

the legal view that states that minerals such as oil and gas cannot be owned in place but rather must be brought to the surface before they can be owned. Also called nonownership, nonownership in place.

a paraffin hydrocarbon, C9H20, that is liquid at atmospheric conditions. Its boiling point is about 303.5°F (150.8°C) at 14.7 pounds per square inch (332.5 kilo­pascals per metre).

gas in a reservoir that contains no oil. Compare associated gas.

areas in the United States that fail to meet NAAQS and that are subject to tighter emission controls and more complicated requirements than are attainment areas. Major new or modified air pollution sources in nonattainment areas must get a permit to build, offset the new emission increase by obtaining reductions from existing sources, and must meet the lowest achievable emission rate.

in process control, a pneumatic device (a relay) whose operating air pressure is retained and sealed in its chamber. Relays transmit, or relay, signals to other components in a process system.

any drilling fluid, usually oil-base or invert-emulsion muds, the continuous phase of which does not conduct electricity, e.g., oil.

wireline used for operations that do not require that electric signals be relayed from downhole to the surface or from the surface to a downhole device.

a material through which little or no free electrons can flow.

a buried landscape in which sediments were deposited on an eroded surface of igneous or metamorphic rock. Compare unconformity.

a provision in a joint operating agreement that allows parties who consent to later operations to penalize parties who do not consent. The penalty can be arranged in various ways but, to be effective, it assumes the productiveness of the proposed operation.

in pipeline construction, testing designed to evaluate the quality of both production and field welds without altering their basic properties or affecting their future usefulness. The most common nondestructive testing is radiographic, or X-ray, testing. Compare destructive testing.

testing methods, such as dye injection and photography, used by divers to find flaws in the structural members of offshore platforms.

a drilling mud that includes lightly treated, low-weight muds and spud muds. No thinners or other chemicals are added to prevent components in the mud from clumping. It is usually employed at the top of the hole and in shallow wells.

an oil that does not take up oxygen from the air and thereby lose its liquid characteristics. A nondrying oil can be added to a paint to slow the paint’s drying.

alloy containing less than 50% iron.

metamorphic rock that appears massive and homogeneous, i.e., without the layered look of foliated metamorphics.

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

terminology to describe the passage entry of seal assemblies into a packer seal bore not locking into place.

a drill collar made of an alloy that does not affect the readings of a magnetic compass placed within it to obtain subsurface indications of the direction of a deviated wellbore. Used in directional drilling.

a working-interest owner other than the one designated as operator of the property.

see nonabsolute ownership.

see nonabsolute ownership.

a person who owns a severed portion of a royalty interest but who does not execute leases, participate in bonuses or rentals, or have rights of exploration and production.

containing no interstices; having no pores and therefore unable to hold fluids.

a turbine compressor.

a tank of conventional shape intended primarily for the storage of liquids at or near atmospheric pressure.

as applied to drilling mud components, those components that are unaffected by and do not react with other components in the mud. Compare reactive.

that part of a liquid drilling mud that consists of solids or other chemicals that do not react with the liquid (or other chemicals in the liquid) part of the mud. Barite, for example, is nonreactive.

well production that is burned in support facilities such as generators and boilers.

a method of treating used when only small amounts of contaminants are removed and/or high purity of treated gas is desired. Compare regenerative process.

on a gate valve, the steel threaded rod (the stem) that, when rotated by an operating wheel, moves the valve’s opening up or down in the valve body to open or close the valve, but does not move into the valve body. A nonrising stem prevents increases in valve body pressure that would occur if the stem entered the body.

any metering device for which the meter pulse output is not derived from mechanical rotation as driven by the flowing stream.

any combination of the fixed-rate and percentage of proceeds type of contract.

in paints, a substance in the liquid phase of the paint that does not readily vaporize at relatively low temperatures.

the liquid, when two liquids are present in a pore, that has only slight, if any, attraction to the sides of the pore and that is repelled by the surface of the rock. Usually, oil is the nonwetting phase and water is the wetting phase. See wetting phase.

an electrical circuit in which output voltage appears only when a signal is absent from all its input terminals.

naturally occurring radioactive materials.

the usual or expected state, form, amount, or degree.

in commercial transactions, a product meeting GPA specification for commercial butane and, in addition, containing a minimum of 95 liquid volume percent normal butane. Chemically, normal butane is an aliphatic compound of the paraffin series with the chemical formula C4H10 and all of its carbon atoms joined in a straight chain.

the smooth, uninterrupted circulation of drilling fluid down the drill stem, out the bit, up the annular space between the pipe and the hole, and back to the surface. Compare reverse circulation.

a resistivity curve made by a conventional electric logging device.

a dip-slip fault along which the hanging wall has subsided relative to the footwall.

formation fluid pressure equivalent to about 0.465 pounds per square inch per foot (10.5 kilopascals per metre) of depth from the surface. If the formation pressure is 4,650 pounds per square inch (32,062 kilopascals) at 10,000 feet (3,048 metres), it is considered normal.

see conventional electric log.

pore pressure where the pressure of any water in the rock equals the hydrostatic pressure of a column of salt water of the same depth.

the pressure developed by a column of fluid as the depth of the column increases when the column contains a fluid of normal density. This gradient varies from area to area, but along the Gulf Coast of the United States, it is considered to be 0.465–0.468 psi/foot (10.53–10.59 kPa/metre), which is the pressure developed by the salt water that naturally occurs in the formations of this area. See normal formation pressure.

a solution that contains 1 gram-equivalent (0.0353 ounce-equivalent) of a substance per litre (3.8 gallons) of solution.

a condition whereby a solution has a concentration of 1 gram equivalent of solute per litre.

1. to make something correspond or conform to a standard or norm. 2. In seismic image processing, a procedure that changes the range of pixel intensity values to make the image appear more familiar or normal to human vision and to achieve consistency in the dynamic range for the seismic data. Also referred to as dynamic range extension.

a factor used to evaluate drilling rate and detecting abnormal pore pressure zones. See d-exponent.

heat-treating applied to metal tubular goods to ensure uniformity of the grain structure of the metal.

a point on the earth’s surface near the north polar region to which a magnetic compass points regardless of the compass’s location on earth. The north magnetic pole is located several miles from the North Pole (the north geographic pole); consequently, navigators must correct for this difference when plotting courses or precisely locating a particular area.

crude oil produced from the Brent field in the British sector of the North Sea. Its price is often quoted, because it is a benchmark for world oil prices.

a rate gyro. See rate gyro.

a strong northerly wind that has different effects in various parts of the world.

the pointed end of the cone of a roller cone bit or the rounded portion of the head of a diamond bit in which the diamonds are embedded.

a hard-metal projection that is placed on the end of the pilot pin of a roller cone bit to absorb some of the wear created by outward thrusts as the bit rotates.

in grated deck flooring on offshore installations, an L-shaped length of steel affixed to the leading edge of a stair tread or to the head of the stair.

see inverter circuit.

metal fatigue concentrated by surface imperfection, either mechanical (such as a notch) or metallurgical (such as a defect in the metal itself).

see letter of protest.

an MMS formal document that provides clarification, description, or interpretations of a regulation or OCS standard; guidelines on the implementations of a special lease stipulation or regional requirement; a better understanding of the scope and meaning of a regulation by explaining MMS interpretations of a requirement; or administrative information.

1. a passageway through jet bits that causes the drilling fluid to be ejected from the bit at high velocity. The jets of mud clear the bottom of the hole. Nozzles come in different sizes that can be interchanged on the bit to adjust the velocity with which the mud exits the bit. 2. the part of the fuel system of an engine that has small holes in it to permit fuel to enter the cylinder. Properly known as a fuel-injection nozzle, but also called a spray valve. The needle valve is directly above the nozzle.

National Pollutant Discharge Elimination System.

a transistor in which n-type material is placed on each side of p-type material. One side of the n-type material is an emitter and the other side is a collector. The p-type material sandwiched in between the two n-type materials is the base. The emitter is negative with respect to the base, while the collector is positive with respect to the base.

National Park Service.

National Response Center; Nuclear Regulatory Commission.

net registered tonnage.

nitrogen rejection unit.

nimbostratus.

National Strike Force Coordination Center.

New Source Performance Standards.

Notice to Lessees and Operators.

see radioactivity log.

a gas, liquid, or solid material that emits gamma rays.

the positively charged central region of an atom, composed of protons and neutrons and containing almost all of the mass of the atom.

1. in mathematics, a member of the set of positive integers; one of a series of symbols of unique meaning in a fixed order that can be derived by counting. A member of any of the further sets of mathematical objects, such as negative integers and real numbers. 2. a symbol or a word used to represent a number.

two grades of domestic fuel oil.

in a mathematical fraction, the term or number that is divided by the other term or number (called the denominator), and is written above the line. For example, in the fraction °/ª, 8 is the numerator.

a flowmeter that operates on the principle of the positive displacement of fluid by incorporating the wobbling motion of a piston or a disk. See positive-displacement meter.

a type of high strength chain certified by DNA. DNV certification is a division of Det Norske Veritas (DNV), an independent foundation established in 1864 as a ship classification society.

NOAA Weather Radio.

National Weather Service.

the price per barrel of West Texas intermediate-grade crude oil as listed on the New York Mercantile Exchange. This price is a benchmark because it is an indicator of oil prices in the United States.