Glossary

shackle type shaped like a D. It is used to connect wire and/or chain sections.

a factor used to evaluate drilling rate and detecting abnormal pore pressure zones. The d-exponent increases with depth when drilling in a normal pressure section. A decrease of the d-exponent with depth indicates abnormal pressure. Also called normalized penetration rate.

an electronic assembly used in a meter that consists of a magnet, a moving coil, a jewel pivot bearing, and a pointer. The pointer sweeps across a dial that can be marked with numerical values expressing current, voltage, resistance, or whatever is appropriate to the application of the meter. It is named after one of its inventors, the French physiologist Jacque-Arsène d’Arsonval.

dry and abandoned; used in drilling reports.

a drilling and production platform. Such an offshore platform is a large structure with room to drill and complete a number of wells.

that daily quantity of gas, formulated on some basis (usually a combination of reserves and delivery capacity or delivery capacity only), that the pipeline company will attempt to take; may or may not equal the take-or-pay quantity.

a record made each day of the operations on a working drilling rig and, traditionally, phoned or radioed in to the office of the drilling company every morning. Also called morning report. See driller’s report.

a tube-shaped device that creates a pressure drop in a fluid flow system. Flow volume can be inferred from the pressure drop. Similar to a venturi, a Dall tube has a short uniform section that is followed by an abrupt shoulder. The shoulder occurs at the front of an inlet cone. A low-pressure tap at the inlet cone’s throat leads to a groove that encircles the throat. Special equipment attached to the tap senses the pressure drop and records it. Named after Horace Dall, a British master optician, who invented the device in the 1950s.

the law that states that the pressure of a mixture of gases is equal to the sum of the partial pressures of the gases of which it is composed. Also called law of partial pressures.

the clause in an oil and gas lease that specifies that the lessee will be liable to the surface owner for damage to growing crops and other listed items.

in reservoir engineering, a measure of the extent of the formation damage in proportion to the formation’s original permeability. Damage ratio expresses the amount of formation damage in terms of a proportion, or ratio. See formation damage.

in ships or offshore rigs, the condition of a vessel’s equilibrium (its stability) when the vessel has suffered enough damage to its hull or structure to allow water to enter (flood) the hull.

an air- or inert gas-filled device that minimizes pressure surges in the output line of a mud pump. Sometimes called a surge dampener.

the dissipation of energy in motion of any type, especially oscillatory motion, and the consequent reduction of decay of the motion.

a valve or plate used to regulate the flow of air or other gas.

see Shock Sub.

decanewton.

a unit of measure of permeability. A porous medium has a permeability of 1 darcy when differential pressure of 1 atmosphere across a sample 1 centimetre long and 1 square centimetre in cross section will force a liquid of 1 centipoise of viscosity through the sample at the rate of 1 cubic centimetre per second. The permeability of reservoir rocks is usually so low that it is measured in millidarcys.

see darcy.

a law stating that the rate of flow of a fluid through a rock varies directly with the amount of interconnected pore space (permeability) and the applied pressure and varies inversely with the viscosity, or flow resistance, of the fluid.

a device, similar to a ball, used to manipulate hydraulically operated downhole tools. See ball.

a drill pipe inside blowout preventer that is installed on top of the drill stem when the well is kicking through the drill stem. It is stabbed in the open position and then closed against the pressure. The valve that closes is dart-shaped, thus the name.

a complete collection of information, such as contained on magnetic disks or in the memory of an electronic computer.

any numerical or geometrical quantity or quantities that serve as a reference or base for other quantities.

a reference elevation, or height, used in mapping, usually sea level.

a height, or elevation, usually sea level, from which altitudes are measured in surveys.

a level metal plate attached to the tank shell or bottom and located directly under the gauging reference point to provide a fixed contact surface from which liquid depth measurement can be made.

the point to which all measurements for the calibration of a tank are related.

an A-frame that booms out 5 to 10 feet over the side of a barge. It has a cable or chain that is lowered to pick up pipeline. A diver attaches the pipeline to the line and it is reeled in on the davit.

an hourly or daily contract price the operator agrees to pay for use of rig, crew, and specified equipment. A day rate contract allows the operator to directly supervise the daily drilling operations.

a fuel tank in the fuel supply system for a diesel engine between the main supply tank and the engine that holds a limited amount of fuel.

(pronounced tower) in areas where two 12-hour tours are worked, a period of 12 daylight hours worked by a drilling or workover crew when equipment is being run around the clock.

(pronounced tower) in areas where three 8-hour tours are worked, the shift of duty on a drilling rig that starts at or about daylight. Compare evening tour, graveyard tour.

in accounting for the safety record of a company, statisticians use DAWF as one measure of how often employees were absent from work because of illness or injury. Low DAWFs may indicate that the company’s safety record is good; conversely, high DAWFs may indicate a bad safety record.

descriptive of work done on daywork rates.

a contract between an operating company and a drilling contractor based on daywork rates. See daywork rates.

the basis for payment on drilling contracts when footage rates are suspended (as when the drilling rig is used in taking extra cores, logging, or other activities that delay actual drilling) or when the contract calls for the entire well to be drilled at daywork rates. In effect, daywork rates pay the drilling contractor by the hour rather than by the foot.

1. direct current. 2. drill collar; used in drilling reports. 3. delivery capacity.

see choke.

discounted cash flow rate of return.

deck decompression chamber.

drag embedment anchor.

see diethanolamine.

a treating system using diethanolamine (DEA) for reduction of hydrogen sulfide, carbon dioxide, carbonyl sulfide, and other acid gases from sour process streams.

in the oil industry, indicates that a well is currently not or is no longer flowing. For example, when a well blows out and the blow out is controlled (stopped), the well is said to be dead.

in a process control system, the difference in the input of a device for a fixed output when operated in ascending and descending directions. For example, a level switch on rising liquid may operate at one level (level x), but also operate at another level (level y) when the liquid level decreases. The difference between level x and y is the dead band. Also called dead zone.

the end of a brake band that is anchored to the drawworks frame and does not move.

oil in which little or no gas is dissolved.

(pronounced “shiv”) the sheave on a crown block over which the deadline is reeved.

1. in a process control system, the time between a change in the input signal and the control system’s response to the signal. 2. in a process, the time that elapses after a response to one signal or event during which a system is unable to respond to another. Also known as insensitive time.

1. a well that has ceased to produce oil or gas, either temporarily or permanently. 2. a well that has kicked and been killed.

the first of several wraps of wire rope around the drawworks drum that will never be played out (unspooled) as the rope moves off the drum.

see dead band.

the drilling line from the crown block sheave to the anchor, so called because it does not move. Compare fastline.

see deadline tie-down anchor.

the sheave on the crown block over which the deadline is reeved.

a device to which the deadline is attached, securely fastened to the mast or derrick substructure. Also called a deadline anchor.

1. a buried anchor to which guy wires are tied to steady the derrick, mast, stacks, and so on. 2. an anchoring point against which the winch on a boring machine for pipelining can pull.

see variable load.

the total carrying capacity of a ship or offshore floating rig expressed in long tons (2,240 pounds); the ship or rig’s deadweight is the displacement of the fully loaded ship or rig less the weight of the ship or rig itself.

see deadweight ton.

any fitting, appurtenance, or structural member that affects the capacity of an oil storage tank. It is positive if it increases tank capacity and negative if it decreases capacity.

a device used for removing air or other noncondensable gases from a process stream or steam condensate and boiler feed water.

a program that may simulate buying and selling transactions.

a device that uses a solvent to reflux, or flow back over, a sample to clean it. Such a device extracts oil or salt-laden water efficiently without harming the core samples.

the removal of asphaltic substances that tend to form carbon deposits when lubricating oils are heated.

in offshore drilling, to remove water from one or more of the pontoons of a semisubmersible drilling rig. When on location and drilling, water, in a controlled manner, is allowed to enter the pontoons of the rig to cause the rig to assume a predetermined submerged position just below the water’s surface. After drilling is finished and it is time for the rig to move to another location, the pontoons are deballasted (some of the ballast water is pumped out) so that the rig can float nearer to the surface to facilitate its movement to another site.

to detect, locate, and correct malfunctions in a computer, instrumentation, or other type of system.

to remove small projections (burrs) from metal pieces or threads.

hydrocarbon mixture remaining after the removal of butane and lighter hydrocarbons.

a unit of equipment for separating butane, with or without lighter components, from a mixture of hydrocarbons and leaving a bottoms product that is essentially butane free.

a group or set of ten, as a period of ten years or a set of ten resistor values.

C10H22, a liquid hydrocarbon of the paraffin series.

ten times the newton, which is the unit of force in the metric system.

a type of mud centrifuge in which a cone-shaped steel bowl rotates very fast. The action of the rotating bowl creates centrifugal force, which causes the mud solids to separate from the liquid.

a base 10 numbering system that includes 10 numbers ranging from 0 to 9; numbers in a system wherein place values are read in powers of 10.

a dot written either on or slightly above the line that is used as the point at which place values change from positive to negative powers of 10 in the decimal numbering system.

a graphic representation of predicted financial gains or losses for the outcomes of several courses of action.

(nautical) floor.

a chamber in which excessive pressure can gradually be reduced to atmospheric pressure. It is especially equipped to help divers complete their decompression schedules and may also be used to treat diving casualties. One or more of the compartments may be installed on the deck of a work boat or barge.

1. the angle, variable with geographic position, between the direction in which a magnetic needle points and the true meridian. 2. a turning aside or swerving.

1. an electronic device that converts binary numbers to decimal numbers. Compare encoder. 2. a demodulator. See demodulate.

the process of gradually lowering elevated ambient pressure to eliminate dissolved gases from a diver’s bloodstream and tissues.

a time-depth profile with a specific bottom time and depth, whose application is calculated to reduce the pressure on a diver safely.

a condition resulting from the formation of gas bubbles in a diver’s blood or tissues during ascent. Failure to rid tissues of the inert gas may cause a wide variety of symptoms, including pain, nausea, paralysis, unconsciousness, temporary blindness, and even death. Also called the bends.

a profile of ascent rates and breathing mixtures that safely reduce the pressure on a diver to atmospheric after a dive. The table shows depths, bottom times, decompression stops, and total decompression times.

materials added to cements or cement slurries to counteract the effects of contamination.

(under HAZWOPER) the removal of hazardous substances from employees and their equipment to the extent necessary to preclude the occurrence of foreseeable adverse health effects.

the act of ending federal government control of the wellhead price of new natural gas sold in interstate commerce. Also called deregulation.

the commitment of reserves of natural gas to a buyer or lessor.

an instrument used to transfer legal title to property as security for the repayment of a loan or the fulfillment of some other obligation. Compare mortgage.

any drilling project that is deeper than average for a given area or time period.

one of the bulk liquid tanks on freighters, usually under the cargo holds.

see exploration well.

in offshore operations, water depths greater than normal for the time and current technology.

see standard dress.

a production pump designed for service in a deep well.

to increase the depth of a well. Deepening is generally a workover operation carried out to produce from a deeper formation or to control excessive gas found in the upper levels of a reservoir.

of or pertaining to operations in deep water.

a relative term that refers to offshore drilling operations in deep oceans or seas-currently, about 5,000 feet (1,500 metres) and deeper. It presents a number of special problems related to water depth.

a marine riser used in deepwater drilling operations and that may be equipped with special devices such as automatic flooding valves, which open to admit seawater into the riser and prevent collapse of the riser when accidental evacuation of mud in a riser occurs. Also, some of the riser joints may be equipped with buoyant riser modules. See buoyant riser joint, riser pipe.

hydrocarbon mixture remaining after the removal of ethane and lighter hydrocarbons.

equipment used to separate and remove ethane by distillation.

large-size hoses used to throw large amounts of water from a distance.

an agreement between working-interest owners of a lease under which an owner’s share of the gas reserves under the lease is considered to remain in the reservoir while the other owner’s share of the gas is being produced.

the difference between the quantity of gas a purchaser is obligated by a gas sales contract to take or to pay for if not taken and the quantity of gas actually taken.

the amount paid by the purchaser for the quantity of deficiency gas as required by a gas sales contract.

see deflection.

an underwater pipe-joining technique in which the pipe is pulled to a target area in line with the platform but to one side of it. The connection is made by winding or otherwise deflecting the pipe laterally until it mates with the riser connection. Compare direct pull-in connection.

a change in the angle of a wellbore. In directional drilling, it is measured in degrees from the vertical.

a device made up in the drill string that causes the bit to drill at an angle to the existing hole. It is often called a kickoff tool, because it is used at the kickoff point to start building angle.

the dispersion of solids that have stuck together in drilling fluid, usually by means of chemical thinners. See flocculation.

any chemical that prevents or lessens frothing or foaming in another agent.

the action of earth stresses that results in folding, faulting, shearing, or compression of rocks.

diethylene glycol.

the device used to remove unwanted gas from a liquid, especially from drilling fluid.

an unwanted substance produced because of some reaction such as cracking, dehydrogenation, or polymerization. The term implies the formation of a contaminant or low-value product.

to break down a compound; to deteriorate.

a unit of measurement of the American Petroleum Institute that indicates the weight, or density, of oil. See API gravity.

a unit of temperature and time, computed per day, equivalent to the difference between a 65˚F (18.3˚C) base and a daily mean temperature (when the latter is less than 65˚F). The total of degree-days for a given period of time can be used to estimate energy requirements such as the amount of fuel oil needed to heat a building.

to remove water from a substance. Dehydration of crude oil is normally accomplished by treating with emulsion breakers. The water vapor in natural gas must be removed to meet pipeline requirements; a typical maximum allowable water vapor content is 7 pounds per million cubic feet (3.2 kilograms per million cubic metres) per day.

the removal of water or water vapor from gas or oil. See dehydrator.

a plant having equipment or apparatus for effecting dehydration.

equipment or apparatus for effecting dehydration.

the process of removing hydrogen from a compound.

ten therms; 1 therm equals 100,000 British thermal units (Btus), which is the heat energy contained in about 97 cubic feet of natural gas, or about 29.3 kilowatt hours (kWh) of energy. In determining the energy content of natural gas, dekatherms are used because 1 dekatherm equals the heat energy equivalent to 1,000,000 British thermal units (Btus), which is a convenient unit of measurement. See British thermal unit.

a phenomenon in which layers of surface metal peel away from the rest of the metal body. Journal (plain) bearings sometimes fail by delamination.

a sum of money payable to the lessor by the lessee for the privilege of deferring the commencement of drilling operations and keeping the lease valid. May be paid monthly, quarterly, or annually.

carcinogens and other hazardous chemicals that cause an adverse effect on a target organ (as defined by the Code of Federal Regulations) that manifests itself after a long period of time following or during repeated contact with the substance.

a well drilled in an existing field to determine, or delineate, the extent of the reservoir.

the liquefaction of a solid substance due to the solution of the solid by adsorption of moisture from the air.

the ability of a gas to be delivered.

the maximum amount of gas a producer can deliver to the purchaser at a specified delivery point.

a graph that compares flowing bottomhole pressure of a well with production in barrels of oil per day to show the relationship between drawdown and the producing rate. Its main purpose is to find the most efficient flow rate for the well.

a type of test for either an oilwell or a gas well to determine the actual flow rate.

1. the actual volume delivered through a meter during a proving or metering operation. 2. a volume of delivered liquid that is measured by a meter. A batch or tender may also be called a delivery. See batch.

the total daily rate that seller maintains and can deliver on demand over an extended period to buyer.

natural gas delivered to a distribution point, such as a gas plant or a city gate. Compare redelivery gas.

see measurement ticket.

a small device used inside a bottle when tap sampling. The tube allows for the delivery of liquid from the tank into the bottle with little or no splashing.

a shipper’s representative who takes delivery of oil from a pipeline company at a terminal or junction.

see lacustrine delta, marine delta.

in electronics, a combination of three components connected in series to form a triangle similar to the Greek letter delta (). Also known as a mesh connection.

valve that opens quickly and allows a full volume of water to flow immediately.

the quantity of oil, gas, or other petroleum products, or commodities (such as electricity) wanted at a specified time and price.

the most commonly used breathing device in commercial diving. The helmet breathes like a scuba regulator. Upon inhalation, the diver is supplied with gas, and upon exhalation, the gas exits the helmet, mimicking a person’s normal respiratory cycle.

a quantity recorder that measures and integrates the instantaneous demands on a circuit during a given period, usually 15 minutes.

the highest rate of power consumption for a minimum period of 15 minutes during a billing period, usually one month. This rate is registered on a demand meter.

the part of the open-circuit diving system that allows a diver to expel all used air directly into the water and avoid rebreathing exhaled carbon dioxide. The regulator reduces the air pressure in the tanks to a diver’s ambient pressure so that he or she can breathe the air with no resistance. Also called open-circuit regulator.

a fractionator used to separate methane and more volatile components from hydrocarbon mixtures. See rich-oil demethanizer.

removing methane in the rejection system that has been retained by the recovery system and cannot be sold as a liquid product.

in an evaporator, a separator that removes droplets of liquid from water vapor.

in electronics, to recover the information transmitted by a modulated wave. See modulate.

in electronics, a small device (a probe) that is placed on or inserted in a circuit and that detects (demodulates) a modulated carrier wave and allows the demodulated signal to be displayed on an oscilloscope’s screen for analysis.

a chemical with properties that cause the water droplets in a water-in-oil emulsion to merge and settle out of the oil, or oil droplets in an oil-in-water emulsion to coalesce, when the chemical is added to the emulsion. Also called emulsion breaker. See demulsify, emulsion breaker.

a combination of a demulsifier and solvent that is used during testing for the suspended S&W content of oil and during other operations.

to resolve an emulsion, especially of water and oil, into its components. See emulsion treating.

drag embedment normal load anchor.

in a mathematical fraction, the term or number that divides the other term or number (called the numerator), and is written below the line. For example, in the fraction 7/15 , 15 is the denominator.

the process of making a substance heavier, or denser. For example, in a gas plant, a product may be densified.

a logging company’s name for a density log.

a device that measures the specific gravity or relative density of a gas, liquid, or solid.

see densimeter.

the mass or weight of a substance per unit volume. For instance, the density of a drilling mud may be 10 pounds per gallon, 74.8 pounds per cubic foot, or 1,198.2 kilograms per cubic metre. Specific gravity, relative density, and API gravity are other units of density.

a special radioactivity log for open-hole surveying that responds to variations in the specific gravity of formations. It is a contact log (i.e., the logging tool is held against the wall of the hole). It emits neutrons and then measures the secondary gamma radiation that is scattered back to the detector in the instrument. The density log is an excellent porosity-measure device, especially for shaley sands. Some trade names are Formation Density Log, Gamma-Gamma Density Log, and Densilog.

a small depression made by striking or pressing. Sometimes called a ding.

to remove, from wax, traces of oil and compounds with a low melting point.

oil removed from a material or from a surface.

a federal department set up to provide a framework for a complete and balanced national energy plan through coordination and administration of the energy functions of the federal government. It is responsible for long-term, high-risk research and development of energy technology, the marketing of federal power, energy conservation, the nuclear weapons program, energy regulatory programs, and a central energy data collection and analysis program. Address: 1000 Independence Ave. SW; Washington, DC 20585; 202-586-5000.

a federal department set up as the nation’s principal conservation agency. The DOI is responsible for nationally owned lands and natural resources. It fosters wise use of land and water resources, protects fish and wildlife, preserves the environmental and cultural values of national parks and historic places, and provides for the enjoyment of life through outdoor recreation. Address: 1849 C Street NW; Washington, DC 20240; 202-208-3100.

see deviation.

a fractionating column in a natural gas plant in which pentane and lighter fractions from a hydrocarbon mixture are removed.

to exhaust a supply. An oil and gas reservoir is depleted when most or all economically recoverable hydrocarbons have been produced.

a hydrocarbon reservoir in which the pressure associated with the hydrocarbons is decreasing. As a reservoir is produced, the pressure energy associated with the reservoir depletes, or decreases.

1. the exhaustion of a resource. 2. a reduction in income reflecting the exhaustion of a resource. The concept of depletion recognizes that a natural resource such as oil is used up over several accounting periods and permits the value of this resource to be expensed periodically as the resource is exhausted.

a reduction in U.S. taxes for owners of an economic interest in minerals in place to compensate for the exhaustion of an irreplaceable capital asset. This economic interest includes mineral interest, working interest in a lease, royalty, overriding royalty, production payment interest, and net profits interest.

see gas drive.

see drilling deployment valve.

the laying down of sediments or other potential rock-forming material.

the set of physical, chemical, and geological conditions (such as climate, stream flow, and sediment source) under which a rock layer was laid down.

a center for storing goods.

1. decrease in value of an asset such as a plant or equipment due to normal wear or passing of time; real property (land) does not depreciate. 2. an annual reduction of income reflecting the loss in useful value of capitalized investments by reason of wear and tear. The concept of depreciation recognizes that the purchase of an asset other than land will benefit several accounting cycles (periods) and should be expensed periodically over its useful life.

in meteorology, an area of low barometric pressure. Depressions often bring rain to the area in which they occur.

to release the pressure contained in a tank, vessel, or pipe to a predetermined value. See bleed.

a unit of equipment for separating propane, with or without lighter components, from a mixture of hydrocarbons and leaving a bottoms product that is essentially propane-free.

1. the distance to which a well is drilled, stipulated in a drilling contract as contract depth. Total depth is the depth after drilling is finished. 2. on offshore drilling rigs, the distance from the baseline of a rig or a ship to the uppermost continuous deck. 3. the maximum pressure that a diver attains during a dive, expressed in feet (metres) of seawater.

the depth of the wellbore when a new bit or other tool is run in. Compare depth out.

the depth of the wellbore when a bit or other tool is pulled out of the hole. Compare depth in.

a device used to measure the depth of a well or the depth at a specific point in a well (such as to the top of a liner or to a fish) by counting the turns of a calibrated wheel rolling on a wireline as it is lowered into or pulled out of the well.

the percentage of the rated power output that a given motor can deliver without being thermally overloaded.

see decontrol.

a clause in a contract currently governed by regulatory price ceilings to provide a process to reset the price of gas should price controls and regulatory authority cease.

in closed-loop control systems, of or pertaining to circuitry or components that change the response of a system to changes in its output or input. Derivative circuits or components are often referred to as rate control circuits or components.

a method of control that adjusts an output based on the rate of change of the process under control.

a large load-bearing structure, usually of bolted construction. In drilling, the standard derrick has four legs standing at the corners of the substructure and reaching to the crown block. The substructure is an assembly of heavy beams used to elevate the derrick and provide space to install blowout preventers, casingheads, and so forth. Because the standard derrick must be assembled piece by piece, it has largely been replaced by the mast, which can be lowered and raised without disassembly. Compare mast.

heavy-lift work platforms used for lifting large components offshore, such as installing or removing offshore platforms.

also called the rig floor or the drill floor. See rig floor.

the crew member who handles the upper end of the drill string as it is being hoisted out of or lowered into the hole. On a drilling rig, he or she is also responsible for the circulating machinery and the conditioning of the drilling or workover fluid.

operation of changing boom angle in a vertical plane.

see derrickhand.

to remove dissolved salt from crude oil. Sometimes fresh water is injected into the crude stream to dissolve salt for removal by electrostatic treaters.

a centrifugal device for removing sand from drilling fluid to prevent abrasion of the pumps. It may be operated mechanically or by a fast-moving stream of fluid inside a special cone-shaped vessel, in which case it is sometimes called a hydrocyclone. Compare desilter.

the laws in a state that determine the disposition of property among heirs in the absence of a will.

a substance able to remove water, liquid, or moisture from another substance with which it is in contact. A dehydration agent. It may be liquid (e.g., triethylene glycol) or solid (e.g., silica gel).

a device used for removing moisture from substances. For drying core samples, the desiccator is a container with a bottom section holding moisture-absorbing chemicals and a top section in which the sample is placed.

engineering plans for the design of a gas processing plant based on the nature of the gas and the product to be marketed.

criteria used in the design of a mooring system.

the ratio of the ultimate load a vessel or structure will sustain to the permissibly safe load placed on it. Such safety factors are incorporated into the design of casing, for example, to allow for unusual burst, tension, or collapse stresses.

see safety factor of wire rope.

the most stressful combination of weight or other forces a mechanical system or device is built to sustain.

1. the vertical distance from the ocean bottom to the nominal water level plus the height of astronomical and storm tides. 2. the deepest water in which an offshore drilling rig can operate.

three-dimensional wells. See three-dimensional wells (3D wells).

a centrifugal device for removing very fine particles, or silt, from drilling fluid to keep the amount of solids in the fluid at the lowest possible point. Usually, the lower the solids content of mud, the faster is the rate of penetration. The desilter works on the same principle as a desander. Compare desander.

the Association of Desk and Derrick Clubs (ADDC) Foundation; an association of employees in the petroleum and allied industries. The principal function of the group is to provide informational and educational programs for the enlightenment of its members about the industry they serve. Membership ranges from secretaries through managers and directors of companies. Address: ADDC Foundation, 14781 Memorial Drive, #57, Houston, TX 77079.

to remove an absorbate or adsorbate from an absorbent or adsorbent.

the process of removing an absorbate or adsorbate from an absorbent or adsorbent.

a procedure in which a weld is torn apart so that its structure can be examined. Destructive testing is used primarily during the qualification procedures required of all welders who work on pipelines.

to remove sulfur or sulfur compounds from oil or gas.

1. a device used to sense or ascertain the presence of such items as objects, radiation, poisonous gases, or chemicals. 2. in an electronic receiver, the stage in the receiver that recovers (demodulates) the modulated signal the receiver originally gets (receives). A modulated signal is a signal that is varied by its amplitude, frequency, or phase. See modulate.

see demodulator probe.

a contact closure change, or other signal, that starts or stops a prover counter/timer and defines the calibrated volume of the prover.

in a pipe prover, an electrical switch activated by the displacement sphere as it moves through the U-portion of the prover. Activating the switch sends an electric current through a cable to a pulse generator.

a mechanism that keeps one part in a certain position relative to that of another; it can be released by applying force to one of the parts.

in lubricating oils and in some engine fuels, a chemical that is added to the oil or to the fuel that suspends dirt, carbon, and other foreign matter in the oil or fuel. As a result of the detergents in motor oil, the oil will very quickly appear dirty because it is suspending the particles.

an interest in property that will end at the happening or nonhappening of a particular event. In some states, an oil and gas lease is considered a determinable fee in real estate.

1. an explosion. 2. the knock or ping produced when fuel of too-low octane rating is used in the engine. Compare preignition.

the isotope of the element hydrogen that has one neutron and one proton in the nucleus; atomic weight is 2.0144.

a plan required by the MMS before development and production can take place in the OCS. The MMS approves or disapproves the plan based on environmental, technical, and economic considerations.

drilling that occurs after the initial discovery of hydrocarbons in a reservoir. Usually, several wells are required to adequately develop a reservoir.

in oil and gas production, the gathering, examination, and analysis of geologic and other data pertaining to newly discovered oil and gas reservoir. From the survey, the operating company will plan how to extract and produce the maximum amount of hydrocarbons from the reservoir.

1. a well drilled in proven territory in a field to complete a pattern of production. 2. an exploitation well.

in drilling, to drill the hole off vertical. In some cases, deviation from vertical is undesirable; in other cases, it may be necessary to efficiently encounter and produce a reservoir.

descriptive of an off-vertical, or deviated, hole.

wells that depart from the vertical, measured by the horizontal distance from the rotary table to the target. See deviating.

when a wellbore departs from vertical; measured by the horizontal distance from the rotary table to the target. The measure of the deviating wellbore is a function of the drift angle and hole depth. The term is sometimes used to indicate the angle from which a bit has deviated from vertical during drilling. See drift angle.

departure of the wellbore from the vertical, measured by the horizontal distance from the rotary table to the target. The amount of deviation is a function of the drift angle and hole depth. The term is sometimes used to indicate the angle from which a bit has deviated from the vertical during drilling. See drift angle.

see double recorder.

when a gas is confined within a pressure-tight container, the tendency of the gas pressure to be slightly above or below that which is normally expected because of the attraction or repulsion of individual gas molecules.

an operation made to determine the angle from which a bit has deviated from the vertical during drilling. There are two basic deviation-survey, or drift-survey, instruments: one reveals the drift angle; the other indicates both the angle and the direction of deviation.

to make a gift of real property (e.g., land) by means of a will. Compare bequeath.

of or relating to the geologic period from about 400 million to 350 million years ago in the Paleozoic era, or to the rocks formed during this period, including those of Devonshire, England, where outcrops of such rock were first identified.

the temperature and pressure at which a liquid begins to condense out of a gas. For example, if a constant pressure is held on a certain volume of gas but the temperature is reduced, a point is reached at which droplets of liquid condense out of the gas. That point is the dew point of the gas at that pressure. Similarly, if a constant temperature is maintained on a volume of gas but the pressure is increased, the point at which liquid begins to condense out is the dew point at that temperature. See dew-point control. Compare bubble point.

the prevention of liquid condensation in the pipeline grid under various pressures and temperatures. Hydrocarbon dew-point control methods include refrigerated low-temperature separation, expanders, Joule-Thomson, and silica gel.

a device used by gas transmission companies to determine and to record continuously the dew point of the gas.

the difference between the actual air temperature and the dew-point temperature.

the temperature at which the rate at which water vapor leaves a gas equals the rate at which water vapor enters the gas at a given pressure.

a high-pressure stainless steel or nickel-plated brass chamber with a magnifying window, a sample inlet, a pressure gauge, a tripod socket, a gas outlet, and an angle-mounted mirror. It ascertains dew point by observing the temperature and the pressure at which condensation occurs on and disappears from the mirror.

the process of removing paraffin from a well whose hydrocarbons become solid (paraffin is a solid hydrocarbon) and impede the flow of liquid and gaseous hydrocarbons from the well.

derrick floor; used in drilling reports.

see diglycolamine®.

downhole safety valve.

the chemical and physical changes that sedimentary deposits undergo (compaction, cementation, recrystallization, and sometimes replacement) during and after lithification.

a thermometer on which the temperature is indicated by a moving needle or pointer on a circular face or disk rather than with liquid in a glass or a liquid crystal display (LCD).

see dial thermometer.

antimagnetic. Diamagnetic materials resist flux by aligning themselves at right angles to the lines of force in a magnetic field. See ferromagnetic, paramagnetic.

the distance across a circle, measured through its center. In the measurement of pipe diameters, the inside diameter is that of the interior circle and the outside diameter that of the exterior circle.

a drill bit that has small industrial diamonds embedded in its cutting surface. Cutting is performed by the rotation of the very hard diamonds over the rock surface.

a sensing element consisting of a thin, usually circular, plate that is deformed by pressure applied across the plate.

in process control instrumentation, a thin pancake-shaped device in a housing, which is part of a control system. Pneumatic pressure from another part of the system travels through tubing into the actuator housing and contacts the diaphragm to move it. The diaphragm then moves a spring or other mechanical device to vary the size of an orifice (opening) through which the control agent flows.

in process control instrumentation, the housing that contains a flexible diaphragm.

part of a diaphragm meter that regulates the length of the diaphragm stroke; used to adjust the volumetric displacement.

a dome or anti­clinal fold in which a mobile plastic core has ruptured the more brittle overlying rock. Also called piercement dome.

the penetration of overlying layers by a rising column of salt or other easily deformed mineral caused by differences in density.

the process or processes of deformation of the earth’s crust that produce oceans, continents, mountains, folds, and faults.

any of the algae of the class Bacillariophyceae, noted for symmetrical and sculptured siliceous cell walls. After death, the cell wall persists and forms diatomite. Diatoms first appeared in the Cretaceous period and still live today.

an earthy deposit made up of the siliceous cell walls of one-celled marine algae called diatoms. It is used as an admixture for cement to produce a low-density slurry.

a rock of biochemical origin, which is composed of the siliceous (glassy) shells of microscopic algae called diatoms.

a tool used to shape, form, or finish other tools or pieces of metal. For example, a threading die is used to cut threads on pipe.

a collar or coupling of tool steel, threaded internally, that can be used to retrieve pipe from the well on fishing jobs; the female counterpart of a taper tap. The die collar is made up on the drill pipe and lowered into the hole until it contacts the lost pipe. If the lost pipe is stuck so that it cannot rotate, rotation of the die collar on top of the pipe cuts threads on the outside of the pipe, providing a firm attachment. The pipe is then retrieved from the hole. It is not often used because it is difficult to release it from the fish should it become necessary. Compare taper tap.

a device similar to a die collar but with external threads.

a substance that is an insulator, or nonconductor, of electricity.

the value of dielectricity assigned to a substance. A substance that is a good insulator has a high dielectric constant, whereas a poor insulator has a low one. The dielectric constant of oil is lower than that of water, and on this principle a net-oil computer operates.

the ability of a dielectric material to withstand the effects of voltage applied to it. It is usually measured in terms of the amount of voltage per mil, or thousandths of an inch, required to break down the material.

a hydrocarbon that contains two carbon double bonds, widely used in the polymer industry.

see insert.

a high-compression, internal-combustion engine used extensively for powering drilling rigs. In a diesel engine, air is drawn into the cylinders and compressed to very high pressures; ignition occurs as fuel is injected into the compressed and heated air. Combustion takes place within the cylinder above the piston, and expansion of the combustion products imparts power to the piston.

a light hydrocarbon mixture for diesel engines, similar to furnace fuel oil; it has a boiling range just above that of kerosene.

a liquid drilling fluid in which diesel oil is the base fluid. An emulsifier and brine (salt water) is also added to allow the brine to disperse within the oil. See oil mud.

the power supplied to a drilling rig by diesel engines driving electric generators; used widely.

see electric rig.

see gunk plug.

colorless, water-soluble, deliquescent crystals, or liquid boiling at 217°C with the chemical formula (HOCH2CH2)2NH; soluble in alcohol and acetone, insoluble in ether and benzene; used as an absorbent of acid gases.

a liquid chemical used in gas processing to remove water from the gas. See glycol, glycol dehydrator.

1. the difference in quantity or degree between two measurements or units. For example, the pressure differential across a choke is the variation between the pressure on one side and that on the other. 2. the value or volume payment accompanying an exchange of oil for oil. The payment serves as compensation for quality, location, or gravity differences between the oils being exchanged.

a special-purpose valve used to facilitate spacing out and flanging up the well, run in on the tubing string.

the reduction in pressure that occurs as gas flows through a restriction in a line, such as through an orifice.

a device installed near the bottom of the casing. It has a valve that keeps mud out of the casing so that the casing can be floated into the hole to lessen the weight on the rig’s equipment. This valve will, however, automatically open to let mud into the casing when the pressure of the mud outside the casing becomes high enough to collapse the joints of casing near the bottom of the string. Thus, this special collar, with its pressure-sensitive valve, not only allows casing to float, but also keeps it from collapsing.

an electronic instrument that measures the difference between the rate of flow of the mud going into the hole and the rate of flow of the mud out of the hole. If the rate of flow coming out of the hole increases, it may be a sign that the well has kicked.

see differential-pressure.

a phenomenon that causes winds to occur on the earth. Because the sun’s light and heat do not strike the earth at the same angle and because some areas of the earth absorb more heat than others, unequal heating takes place. Consequently, some areas receive more light and heat than others. For example, the sun’s light and heat strike the equator at a more direct angle than at the poles. Thus, it is hotter at the equator than it is at the poles. Also, because ice at the poles reflects more light than the vegetation at the equator, the equatorial regions are hotter than polar regions.

on a flow recorder, the pen used to record differential pressure across the orifice in the meter; usually recorded in red ink on the flow recorder chart.

the extent of variation between the lowest and highest differential pressures that an orifice meter can accurately measure.

in a circuit, an indicator (a signal) that is the voltage difference between two junctions (nodes), neither of which is at ground potential.

a condition in which the drill stem becomes stuck against the wall of the wellbore because part of the drill stem (usually the drill collars) has become embedded in the filter cake. Necessary conditions for differential-pressure sticking, or wall sticking, are a permeable formation and a pressure differential across a nearly impermeable filter cake and drill stem. Also called wall sticking. See differential pressure, filter cake.

a test taken at a particular point in the flow of a meter, which is compared with the same flow rate on a differential curve that was established at the time the meter was installed. If the differential pressure reading obtained during the test is 50% higher than the original test value (at the same flow rate), with pressure and temperature conditions being approximately the same, the meter is removed and the cause of the increased operating resistance determined.

the pressure existing across an orifice plate in a fluid flow application; pressure is converted into flow units. The difference between two fluid pressures; for example, the difference between the pressure in a reservoir and in a wellbore drilled in the reservoir, or between atmospheric pressure at sea level and at 10,000 feet (3,048 metres). Also called pressure differential.

a pressure-measuring device actuated by two or more pressure-sensitive elements that act in opposition to produce an indication of the difference between two pressures.

a pressure-measuring device actuated by two or more pressure-sensitive elements that act in opposition to produce an indication of the difference between two pressures.

see differential sticking.

an electrical device that senses very small bellows or diaphragm movement in a bellows meter. Allows a computer to calculate flow rates directly by producing electrical output.

1. a pressure measuring device that senses the difference between two pressures and produces a proportional electrical output, usually 4 to 20 milliamps (mA), which covers the calibrated range of the transmitter. 2. an electrical device that senses very small bellows or diaphragm movement in a bellows meter. 3. an electrical device that allows a computer to calculate flow rates directly by producing an electrical output that is proportional to the square root of the differential pressure measured by the transmitter.

a valve used to regulate automatically a uniform difference in pressure between two locations in a pipeline.

a circuit whose output voltage is proportional to the rate of change of the input voltage.

a device that uses part of the kinetic energy of a fluid passing through a machine by gradually increasing the cross section of the channel or chamber through which it flows so as to decrease its speed and increase its pressure.

1. the spontaneous movement and scattering of particles of liquids, gases, or solids. 2. the migration of dissolved substances from an area of high concentration to an area of low concentration.

a warning sign posted on top of or otherwise near a site of a buried cable, pipe, or line, which could be damaged if a digging or trenching machine encountered the buried cable, pipe, or line.

a character that represents a numeric character. See number.

pertaining to data in the form of digits, especially electronic data stored in the form of a binary code. Compare analog.

a system that describes a statement or condition in a true-false, yes-no, either-or, or on-off manner. Digital logic is used in computer operating systems and in automatic switching and control systems. adj: of or pertaining to the various types of solid-state devices such as gates, flip flops, and other on-off circuits used to perform problem-solving functions in the many types of digital computers.

in electronics, a multimeter that is constructed such that its measurements are displayed digitally rather than as analog readouts. See multimeter.

a type of register on which the information is indicated by directly readable characters, particularly numerals. Compare analog data.

the representation of the magnitude of a variable in the form of discrete values or pulses of a measurable physical quantity.

a solvent used for the removal of CO2 or H2S from gases.

(CH3CHOHCH2)2NH. A white, crystalline solid with a boiling point of 248.7°C used as a chemical intermediate agent for removal of hydrogen sulfide from natural gas.

a dilatant, or inverted plastic, fluid is usually made up of a high concentration of well-dispersed solids that exhibits a nonlinear consistency curve passing through the origin. The apparent viscosity increases instantaneously with increasing rate of shear. The yield point, as determined by conventional calculations from the direct-indicating viscometer readings, is negative; however, the true yield point is zero.

liquid added to dilute or thin a solution.

a technique that involves the study of the dimensions of physical quantities, which is used primarily as a tool for obtaining information about physical systems too complicated for full mathematical solutions to be feasible.

a number that does not have a unit of measurement associated with it.

a device used to attach a tool string to the end of coiled tubing. It absorbs vibration created by rotating or reciprocating the tubing and provides a high-pressure seal between the tool string and the coiled tubing.

a device used in coiled tubing operations that absorbs forces created when drilling with downhole motors or when using impact hammers. The grapple connector provides high tensile strength and high torque capacity.

1. a solid-state electronic device that restricts current flow chiefly in one direction. 2. a radio tube that contains an anode and a cathode.

in a circuit in which a diode is used, the voltage generated at the point where (the junction) the diode is wired into the circuit. Junction voltage is 0.7 volts and when multiplied by the current flowing in the circuit results in wattage, which takes the form of heat.

intrusive, or platonic, generally coarse-grained igneous rock composed largely of plagioclase feldspar with smaller amounts of dark-colored minerals. Also known as black granite. Compare andesite.

1. a European term for the depth of liquid in a storage tank. 2. formation dip. See formation dip, innage, ullage.

a European term for the point on the bottom of a container that the dip weight touches during gauging and from which the measurement of the oil and water depths is taken. The dip point usually corresponds with the datum point, but any difference in levels must be designated in the calibration table.

a European term for the opening in the top of a container through which dipping (gauging) and sampling operations are carried out.

see dipmeter survey.

a European term for datum plate.

a rigid length of wood or metal that is provided with a scale for measurement and usually graduated in units of volume. It is used for manual measurement of liquid in a container. Also called dipstick.

upward or downward displacement along a fault plane.

a European term for gauging tape.

the small-diameter tube extending below the pump suction of a sucker rod pump, usually inside the mud anchor, as in a “poor boy” gas anchor.

a European term for a plumb bob that is attached to a metal dip tape and that is of sufficient weight to keep the tape taut and of such shape as to facilitate the penetration of any sludge that might be present on the datum plate of a tank. Also called outage bob.

a fault in which the slip is practically in the line of the fault dip.

see diisopropanolamine.

see dipmeter survey.

an oilwell-surveying method that determines the direction and angle of formation dip in relation to the borehole. It records data that permit computation of both the amount and direction of formation dip relative to the axis of the hole and thus provides information about the geologic structure of the formation. Also called dipmeter log or dip log.

a European term for a point marked on the dip hatch of a tank directly above the dip point to indicate the position at which dipping should be carried out.

see dip rod.

a straightforward connection that makes the speeds of a prime mover and a driven machine identical.

in electronics, the joining (coupling) of two circuits with a nonfrequency-sensitive device, such as a wire, resistor, or battery, so that both direct and alternating current can flow through the coupling path. For an oscilloscope to measure direct current, its circuits must be direct coupled.

in an electric circuit, current flow in one direction only. An example of a simple DC circuit is a battery, a wire, and a light bulb, wherein current flows through the wire from one terminal of the battery, through the light bulb, and through another wire back to the battery’s other terminal. Compare alternating current.

used in emulsion treating to heat noncorrosive emulsions that are under comparatively low pressure. Types are tubular, fluid-jacket, internal firebox, and volume, or jug-type. Compare indirect heater.

a measurement that produces a final result directly from the scale on an instrument.

an underwater pipe-joining technique in which the pipe with its connector sled is steered straight onto the matching receiver at the base of the platform. Compare deflect-to-connect connection.

a type of orifice meter chart that indicates the differential pressure and static pressure for a particular time period. The pressures can be read directly from the chart instead of being calculated from information given on the chart.

a natural gas sales transaction in which at least one of the intermediary parties in the natural gas delivery system (i.e., pipeline transmission company or local distributing company) does not take title to the natural gas but only transports it. Historically, a sale of natural gas to an end user, as opposed to a “sale for resale.” More recently, the term has also been applied to a sale by a producer directly to a local distribution company.

a device on a diesel engine’s governor that increases the engine’s speed by increasing positive voltage going to the actuator and governor. As the engine needs more fuel to go faster, the direct-acting actuator increases positive voltage to make the governor increase the fuel flowing to the fuel injectors. See electrically-actuated governor.

see direct-reading viscometer.

commonly called a “V-G meter.” The instrument is a rotational-type device powered by means of an electric motor or handcrank, and is used to determine the apparent viscosity, plastic viscosity, yield point, and gel strengths of drilling fluids. The usual speeds are 600 and 300 rpm. See API RP13B for operational procedures.

an employee of a directional drilling service company whose main job is to help the driller at a well site keep the wellbore as close as possible to its planned course.

1. intentional deviation of a wellbore from the vertical. Although wellbores are normally drilled vertically, it is sometimes necessary or advantageous to drill at an angle from the vertical. Controlled directional drilling makes it possible to reach subsurface areas laterally remote from the point where the bit enters the earth. It often involves the use of deflection tools. 2. a technique of river crossing in pipeline construction in which the pipe is buried under the riverbed at depths much greater than those of conventional crossings. With this technique, a hole in the form of an inverted arc is drilled beneath the river, and the made-up pipeline is pulled through it.

the oil company operating the well project.

a business that provides directional hole planning, sophisticated directional tools, and on-site assistance to the oil company operator of a drilling rig.

an employee of a directional drilling service company whose main job is to help the driller at a well site keep the wellbore as close as possible to its planned course. Also called directional operator.

a wellbore intentionally drilled at an angle from the vertical. See directional drilling.

see directional drilling supervisor.

see oriented perforating.

a logging method that records drift angle, or deflection from the vertical, and direction of the drift. A single-shot directional-survey instrument makes a single photograph of a compass reading of the drift direction and the number of degrees the hole is off vertical. A multishot survey instrument obtains numerous readings in the hole as the device is pulled out of the well. See directional drilling.

a tool that, when lowered into the wellbore, makes a photographic record of the angle and drift of the wellbore; that is, it records the number of degrees the hole is off vertical and the direction in which it is off vertical. Several types of instrument are available; some are capable of photographing only a single record-single-shot survey instruments-whereas others are capable of making several records in one run-multishot survey instruments.

see optical pyrometer.

a common coating failure in which the coating separates from the pipe.

a measure of the efficiency with which gas flows through an actual orifice. Compares the actual orifice’s discharge rate with an ideal orifice’s discharge rate.

a line through which drilling mud travels from the mud pump to the standpipe on its way to the wellbore.

any addition of dredged material into U.S. waters.

pressure generated on the output side of a gas compressor.

on a mud pump, the valve that opens to allow mud to be pushed out of the pump (discharged) by the pistons moving in the liners.

the total calculated volume (TCV) by vessel measurement on arrival, less remaining on board (ROB), divided by the TCV by shore measurement at discharge.

complete denial and renunciation of any claim to title to property. Surface tenants, for example, often sign disclaimers (in the form of tenant consent agreements) relating to the mineral estate and title of land leased for oil and gas exploration.

an interruption in sedimentation caused by erosion; the strata above and below the disconformity are parallel. See unconformity. Compare nonconformity.

a device such as a switch or circuit breaker used to open a circuit.

the intermittent and irregular fluctuation (a pulse) of direct current flowing in a circuit. DC current pulses create heat in the circuit and can affect the operation of solid-state diodes whose temperature rating is not sufficient to withstand the heat created by such pulses.

the rate that causes the sum of the discounted outflows and inflows of funds to equal the net cash outlay in year zero of a project. It is used in evaluating exploration investments.

taking account of future value in present calculations, i.e., determining present value of future dollars. Discounting is compounding in reverse.

the first oil or gas well drilled in a new field that reveals the presence of a hydrocarbon-bearing reservoir. Subsequent wells are development wells.

in electronic process control systems, of or pertaining to a device that is either on or off.

the ability to sense and record the actual temperature of a liquid to the specified temperature increments.

a brake on a drawworks in which two large metal disks are affixed to each end of the drawworks drum. When the brake is actuated, large gripping devices called calipers contact the disks to stop the drawworks from turning. Disk brakes are gradually replacing band brakes on drawworks.

see slinger disk lubrication.

a type of compressor valve in which springs and disks are used to open and close the valve.

an employee responsible for scheduling movement of oil through pipelines.

a substance added to cement that chemically wets the cement particles in the slurry, allowing the slurry to flow easily without much water.

a drilling mud to which a chemical-a dispersant-is added to cancel the attractive forces between the particles in the mud that create viscosity. As depth and mud weight increase, these attractive forces may become so high that the mud’s viscosity cannot be adequately controlled without dispersants.

that part of a drilling mud-clay, shale, barite, and other solids-that is dispersed throughout a liquid or gaseous medium, forming the mud.

see emulsifying agent.

an inhibitor substance that can be dispersed evenly in another liquid with only moderate agitation.

a suspension of extremely fine particles in a liquid (such as colloids in a colloidal solution).

see continuous phase.

a colloid or finely divided substance. See also colloid.

1. the weight of a fluid (such as water) displaced by a freely floating or submerged body (such as an offshore drilling rig). If the body floats, the displacement equals the weight of the body. 2. replacement of one fluid by another in the pore space of a reservoir. For example, oil may be displaced by water.

the proportion by volume of oil swept out of the pore space of a reservoir by the encroachment of another fluid. The displacing fluid may be reservoir water or gas or an injected fluid.

see reciprocating engine.

in oilwell cementing, the fluid, usually drilling mud or salt water, that is pumped into the well after the cement is pumped into it to force the cement out of the casing and into the annulus.

1. a meter in which a piston is actuated by the pressure of a measured volume of liquid, and the volume swept by the piston is equal to the volume of the liquid recorded. 2. a meter in which the measuring element measures a volume of liquid by mechanically separating the liquid into discrete quantities of fixed volume and counting the quantities in volume units.

a device used to pump liquids, usually at high pressures, with an action similar to that of a piston.

a measurement of the speed with which a volume of cement slurry or mud is pumped down the hole.

the weight in long tons (a long ton equals 2,240 pounds) of the water a ship or floating offshore rig displaces. A ship or rig displaces an amount of water whose weight is equal to the ship or rig’s weight and its contents.

a spherical or cylindrical object that is a component part of a pipe prover that moves through the prover pipe. The displacer has an elastic seal that contacts the inner pipe wall of a prover to prevent leakage. The displacer is made to move through the prover pipe by the flowing fluid and displaces a known measured volume of fluid between two fixed detecting devices.

a well into which salt water or spent chemical is pumped, most commonly part of a saltwater-disposal system.

the separation of a molecule into two or more fragments (atoms, ions) by interaction with another body or by the absorption of electromagnetic radiation.

natural gas that is in solution with crude oil in the reservoir.

in a flowing stream of water, those products of weathering that are carried along in solution. Compare bed load, suspended load.

water in solution in oil at a defined temperature and pressure.

a source of natural reservoir energy in which the dissolved gas coming out of the oil expands to force the oil into the wellbore. Also called solution-gas drive. See reservoir drive mechanism.

an oil reservoir in which the liquid is driven from the reservoir by the expansion of dissolved gas.

the delay caused by the amount of time required to transport material or propagate a signal or condition from one point to another. Also known as transportation lag, transport lag.

1. a product of distillation, i.e., the liquid condensed from the vapor produced in a still. Sometimes called condensate. 2. heavy gasoline or light kerosenes used as fuels.

light fuel oils distilled during the refining process and used primarily for space heating, on-and-off-highway diesel engine fuel, and electric power generation.

the process of driving off gas or vapor from liquids or solids, usually by heating, and condensing the vapor back to liquid to purify, fractionate, or form new products.

a tall cylindrical steel tower where, in atmospheric distillation, the process takes place at atmospheric (normal) pressure.

the apportioning of daily production rates to wells on a lease. Because there may be many wells on a lease, such production is apportioned on the basis of periodic tests rather than on the individual receiving and gauging of oil at each well.

in a gas distribution system, such as in a city or town, a relatively large pipeline through which gas is supplied to several smaller pipelines. The smaller lines provide gas to homes, schools, and other buildings.

a system of pipelines and other equipment by which natural gas or other products are distributed to customers, to lease operations, or to other points of consumption, that is, the mains, services, and equipment that carry or control the supply of gas from the point of local supply to and including the sales meters.

an electrical device designed to reduce voltage from primary distribution levels, usually 7,200 or 12,400 volts, to utilization voltages of 480, 240, or 120 volts. See power transformer (def. 1).

a device that directs the proper flow of fuel or electrical current to the proper place at the proper time in the proper amount.

on a diesel engine with a distributor-type fuel injection system, the sequence in which the distributor sends fuel to each engine cylinder.

station to which odorized gas is piped from the city gate station. This station uses regulators and controllers to maintain consistent pressure and to ensure a constant supply of natural gas to consumers. See city gate station.

chemical compounds containing an -S-S linkage. They are colorless liquids completely miscible with hydrocarbons, insoluble in water, and sweet to the doctor test. Mercaptans are converted to disulfides in treating processes employing oxidation reactions.

a trench or channel made in the earth, usually to bury pipeline, cable, and so on. On a drilling rig, the mud flow channel from the conductor-pipe outlet is often called a ditch. See mud return line. v: to excavate a trench in which to lay pipe or cable. Ditching equipment and methods for pipe laying vary according to terrain and weather.

a device that divides a ditch into sections to form internal barriers to water movement. Ditch breakers are used for pipelines in areas where washouts are a threat.

a powerful magnet placed in the return line between the wellbore and the mud pit to remove metal particles from the drilling mud. A ditch magnet is often used during milling operations.

a tide having one high water level and one low water level a day.

see com box.

the site from which diving operations are directly controlled. This site shall also include any auxiliary or peripheral equipment necessary to the conduct of the diving operation.

the dive supervisor, or designated dive superintendent, having complete responsibility for the safety of the diving operation including the responsibility for the safety and health of all diving personnel.

an offshore supply vessel between 100 and 300 feet (30 to 107 metres) in length and usually tied up alongside the offshore platform from which work will be performed.

a portable building that contains equipment to monitor all systems of the bell and the diver in the water.

a highly trained and nationally certified medical technician who specializes in diving and hyperbaric-related maladies and emergency medicine.

a diver-carried supply of air or mixed gas to allow the diver to reach the surface, or another source of breathing gas, or to be reached by a stand-by-diver. Also called EGS (Emergency Gas Supply) or Bail Out Bottle.

that equipment required for the safety and well-being of the diver, worn or attached to the diver while underwater.

in offshore drilling, an assembly of devices used to direct fluids flowing from a well away from the drilling rig. When a kick is encountered at shallow depths, the well often cannot be shut in safely because shutting it in on a shallow formation may create pressures high enough to fracture (break down) the formation. Therefore, a diverter is used. When activated, it allows well fluids to flow through a side outlet to a line (pipe) that carries the well fluids a safe distance away from the rig. A diverter contains a packing element, flow-line seals, and lock-down mechanisms and is run and retrieved with a special handling tool made up on riser pipe.

see diverter.

a side outlet on a rig that directs flow away from the rig.

see diverter.

a type of valve that changes the direction of fluid flow from the intended path to an alternate route.

type of operating agreement that provides for sharing of costs and benefits based on participating areas that may change.

a fractional interest in minerals that, when conveyed, gives the new owner a 100% interest in the designated fraction of the described tract. For example, a one-quarter divided interest in an 80-acre (32-hectare) tract results in a 100% interest in 20 specific, describable acres (8 hectares) out of that tract. Compare undivided interest.

in mathematical division, the quantity that is divided by another quantity. For example, in 9 ÷ 3 = 3, 9 is the dividend.

a cylindrical or spherical compartment used to transport a diver or dive team to and from an underwater work site. See bell and submersible decompression chamber, SDC.

any work operation requiring some type of diving or work underwater that involves planned human exposure to increased pressures to perform the job.

a type of basket where the diver can both perform decompression stops and enter or exit the water). The stage is constructed open on one side with hand holds inside and protection around the occupant. The stage is lowered from the surface by a davit and winch. A crewmember controls the winch while being directed by a supervisor.

a contract of sale of oil or gas to a purchaser who is directed to pay for the oil or gas products according to the proportions set out in the division order. The purchaser may require execution thereof by all owners of interest in the property.

a statement of opinion by a title examiner on the state of the title to land, mineral, royalty, or working interests in a producing tract of land. This opinion, usually in letter form, is the basis of payment to all affected owners and must recite all the owners’ interests. Compare drill site opinion, title opinion.

in mathematical division, the quantity by which another quantity is divided. For example, in 12 ÷ 3 = 4, 3 is the divisor.

a mechanism used in packers to lock components together.

dark; used in drilling reports.

dogleg severity.

a component of an equation related to dogleg severity. See dogleg severity.

diver medic.

a qualitative method for detecting hydrogen sulfide and mercaptans in petroleum distillates. The test distinguishes between sour and sweet products.

Department of Energy.

1. a spring-loaded finger in a tubing end locator. 2. any of various simple devices for holding, gripping, or fastening, such as a hook, rod, or a spike with a ring, claw, or lug at the end.

see safety clamp. Also called collar clamp or drill collar clamp.

a riser connector that has actuator screw assemblies in the box end. Tightening the screws with pneumatic torque wrenches causes tapered locking dogs to engage mating tapers in the pin end. The application of the correct torque to the actuator screw, combined with the taper geometry of the pin and locking dogs, preloads the connection to the design load rating. Spring-loaded locks prevent vibration from backing out the actuator screws. The actuator screws do not support any of the riser connection’s load. See hydraulic connector.

1. a small enclosure on the rig floor used as an office for the driller and as a storehouse for small objects. 2. any small building used as an office, a change house, or a place for storage.

1. an abrupt change in direction in the wellbore, frequently resulting in the formation of a keyseat. 2. a sharp bend permanently put in an object such as a pipe, wire rope, or a wire rope sling.

the amount of change in angle or direction of the wellbore, measured in degrees per 100 feet or degrees per 30 metres.

an upper kelly cock that is enclosed in a ball-shaped housing.

Department of the Interior.

dolomite; used in drilling reports.

see pipe dolly.

on a top-drive unit, the device that attaches the unit to the guide rails. See guide rails, top drive.

dolomite; used in drilling reports.

a type of sedimentary rock similar to limestone but containing more than 50 percent magnesium carbonate; sometimes a reservoir rock for petroleum.

the shrinking of the solid volume of rock as limestone turns to dolomite, i.e., the conversion of limestone to dolomite rock by replacement of a portion of the calcium carbonate with magnesium carbonate.

rock composed of dolomite.

a geologic structure resembling an inverted bowl, i.e., a short anticline that dips or plunges on all sides.

a reservoir formation in which fluid or plastic masses of rock material originated at unknown depths and pierced or lifted the overlying sedimentary strata.

a storage tank with a dome-shaped roof affixed to the shell.

(slang) a person who prospects for oil, especially by using seismology. Also called doodlebugger. v: (slang) to explore for oil, especially by using seismic techniques in which explosive charges are detonated in shot holes to create shock waves (name taken from the resemblance of these explosions to the puffs of loose dirt thrown up by the doodlebug, or ant lion, when digging its funnel-shaped hole).

a plate at the base of a tank shell or wall that is removed so the tank can be cleaned.

a lubricant for the threads of oilfield tubular goods. v: to apply thread lubricant.

the container in which dope is stored on the rig floor.

a portable container used to melt coal tar enamel and maintain it at the temperature required by a pipe-coating operation.

1. the addition of impurities to a semiconductor to achieve a desired characteristic, such as producing n- or p-type material. See n-type structure, p-type structure. 2. applying lubricant (dope) to a tool joint or other threaded connection.

dropoff rate.

U.S. Department of Transportation.

a length of drill pipe, casing, or tubing consisting of two joints screwed together. Compare fourble, single, thribble.

the name used for the working platform of the derrickhand (the monkeyboard) when it is located at a height in the derrick or mast equal to two lengths of pipe joined together. Compare fourble board, thribble board.

a chemical linkage consisting of two atoms that share two pairs of electrons (a covalent bond) between two atoms of a molecule. In short, when four electrons are shared between two atoms, the atoms have a double bond.

a pipe incorporating twice as many safety design factors as normally used.

a tool employing gripping devices (slips) that limit tool movement from pressure either above or below the tool.

in oil tankers (ships that transport oil on the ocean), construction that consists of an inner and an outer hull. Double hulls help prevent oil spills should the tanker strike an object that penetrates the outer hull. The inner hull prevents oil from leaking from the vessel. Some oil storage tanks on land also have double hulls for the same reason that tankers have them.

tanker with two hulls. Theoretically, the first hull absorbs all or most of any impact, leaving the second hull intact or less damaged and thus able to contain the cargo.

the process of welding two pipe joints together-usually on a double-joint rack-to form a single piece of pipe. The usual length of a double joint for pipeline construction is 80 feet (24 metres).

a device containing an angle indicator, a timing element, and a replaceable chart that is used to measure the direction and the degree of deviation as a hole is being drilled. The timing element goes off when the tool has come to rest just above the drill bit and descends on the sharply pointed angle indicator, which then punches a hole in the chart. The chart rotates 180˚, and a second hole is punched to verify a correct reading of the resting angle of the tool.

in reference to a mud pump, the action of the piston moving mud through the cylinder on both its forward and backward stroke. Compare single-acting.

a special coupling that has a female connection (box) on each end and that is used to connect sucker rods that have a male connection (pin) on each end.

a device consisting of two reels on which wire rope is wound that provides two separate hoisting drums in the assembly. The main drum is used for pulling tubing or drill pipe; the second drum is used for coring and swabbing. See hoist.

in a kelly bushing, a double set of roller assemblies that are installed on two levels, or planes, within the bushing. Compare single-plane roller assembly. See also kelly bushing, roller assembly.

a six terminal electrical switch that simultaneously connects one pair of terminals to either of other pairs of terminals.

an electrical switch with four terminals that simultaneously opens or closes two separate circuits or both sides of the same circuit.

a well-servicing unit whose mast consists of two steel tubes. Double-pole masts provide racking platforms for handling rods and tubing in stands and extend from 65 to 67 feet (20 to 20.4 metres) so that rods can be suspended as 50-foot (15-metre) doubles and tubing set back as 30-foot (9-metre) singles. See pole mast.

a drilling or workover rig whose derrick height is tall enough to allow crew members to set back drill pipe, drill collars, or tubing in stands of doubles; a double stand is made up of two joints of pipe, collars, or tubing.

a ring of wedges or a threaded, tapered ring that supports a string of pipe.

a cutout section in a cone enabling positive slip movement without the aid of conventional slip return springs.

a pin fitting into a hole in an abutting piece to prevent motion or slipping.

in some states, that part of an estate to which a wife is entitled (for her lifetime) on the death of her husband.

a device that measures the saturation, or the amount, of each fluid in a core sample by distilling the fluid from the core with heat. The core sample is heated to about 350˚F (176.7˚C). The fluids are vaporized and cooled until they condense in receiving tubes, where they are measured.

in marine architecture, the angle of a vessel at which nonwater­tight openings on the main deck start to submerge.