Glossary

1. capacitance. 2. Celsius (formerly centigrade). See Celsius scale.

1. carbon 2. coulomb.

1. the rate of flow in cubic feet per hour at base conditions. 2. a factor used in the calculation of gas volume flow through an orifice meter, now largely supplanted by an equation formulated in 1992. Mathematical accounting for variations in pressure, temperature, density, and so on, of a gas as it flows through an orifice of a particular size. Also called orifice flow constant; formerly called flow coefficient.

Clean Air Act.

a housing which covers the revolving superstructure machinery and operator’s station.

1. a rope of wire, hemp, or other strong fibers; often, but not always, personnel in the petroleum industry call it cable wire rope. 2. in electronics, a wire made of a conducting material such as copper or aluminum. Usually, cable is braided from several single strands of wire into a single conductor that is easier to bend than a solid wire of the same gauge. 3. in electronics, a wire made of a conducting material such as copper or aluminum. Usually, cable is braided from several single strands of wire into a single conductor that is easier to bend than a solid wire of the same gauge.

a fishing device made up on a cable-guide assembly to prevent the cable from falling in the hole. It is used in the recovery of wireline tools.

in offshore drilling from floating drilling rigs, a large spool around which is wrapped the electric cable that provides the link between the surface power and electronics and the subsea power and electronics on the lower marine riser package and the subsea blowout preventer stack. Because most subsea blowout preventers have two operational systems in case one fails, two cable reels are usually provided. A typical cable reel can store over 10,000 feet (3,000 metres) of cable.

fishing equipment used to recover wireline tools stuck in the hole when the wireline or cable is intact. It consists of a cable hanger, spear point rope socket, spearhead overshot, conventional overshots, drill pipe, and elevators.

a method of retrieving wireline tools using a cable-guide assembly.

a form of electric submersible pumping for artificial lift, in which the pump can be run or pulled on the power cable. This type of pump installation is made possible by power cables designed for tensile loads in excess of 100,000 pounds (45,360 kilograms).

a drilling method in which the hole is drilled by the rig’s equipment dropping a sharply pointed and heavily weighted bit on bottom. The bit and weight are attached to a cable, and the rig’s equipment repeatedly drops the cable to drill the hole.

a drilling rig that uses wire rope (cable) to suspend a weighted, chisel-shaped bit in the hole. Machinery on the rig repeatedly lifts and drops the cable and bit. Each time the bit strikes the bottom of the hole, it drills deeper. Rotary drilling rigs have virtually replaced all cable-tool rigs.

a sucker rod pumping unit, not commonly used, that employs cable wound around a spool, one end going into the hole, the other with a suspended counterweight. This type of unit can achieve 40- to 80-foot (12- to 24-metre) stroke lengths, reducing dynamic loads, rod reversals, gas locking, and power usage and can be applied to deep pump applications.

compressed air energy storage.

in a sucker rod pump, the device that contains and confines the valve ball and keeps it the proper operating distance from the valve seats.

a special wrench designed for use in connecting the cage of a sucker rod pump to the sucker rod string.

1. one of several columns made of steel or concrete that serve as the foundation for a rigid offshore platform rig, such as the concrete gravity platform rig. 2. a steel or concrete chamber that surrounds equipment below the waterline of an Arctic submersible rig, thereby protecting the equipment from damage by moving ice.

a drilling platform that rests on a steel or concrete caisson. Used mainly in the Arctic, caisson-type drilling platforms are mobile offshore drilling units built to withstand the ravages of moving ice in Arctic waters.

see filter cake.

the character or state of the drilling mud filter cake. According to API RP 13B, such notations as “hard,” “soft,” “tough,” “rubbery,” and “firm” may be used to convey some idea of cake consistency.

the thickness of drilling mud filter cake.

containing or composed largely of calcium carbonate, or calcite (CaCO3).

calcium carbonate, CaCO3.

one of the alkaline earth elements with a valence of 2 and an atomic weight of about 40. Calcium compounds are a common cause of water hardness. Calcium is also a component of lime, gypsum, and limestone.

a chemical combination of calcium, carbon, and oxygen, CaCO3. It is the main constituent of limestone. It forms a tenacious scale in water-handling facilities and is a cause of water hardness.

a moisture-absorbing chemical compound, or desiccant, CaCl2, used to accelerate setting times in cement and as a drying agent. It is also added to fresh water to increase the water’s weight and to give it desirable properties during well completion or workover.

dissolved calcium ions in sufficient concentration to impart undesirable properties, such as flocculation, reduction in yield of bentonite, and increased fluid loss, in a drilling fluid. See also anhydrite, calcium carbonate, calcium sulfate, gypsum, lime.

the active ingredient of slaked (hydrated) lime, and the main constituent in cement (when wet). Referred to as “lime” in field terminology. Its symbol is Ca(OH)2.

a chemical combination of calcium, magnesium, carbon, and oxygen; the main constituent of dolomite. Its chemical formula is CaMgCO3. See dolomite. Compare calcium carbonate.

a chemical compound of calcium, sulfur, and oxygen, CaSO4. Although sometimes considered a contaminant of drilling fluids, it may at times be added to them to produce certain properties. Like calcium carbonate it forms scales in water-handling facilities, which may be hard to remove. See anhydrite, gypsum.

a freshwater drilling mud using calcium oxide (lime) or calcium sulfate (gypsum) to retard the hydrating qualities of shale and clay formations, thus facilitating drilling. Calcium-treated muds resist salt and anhydrite contamination but may require further treatment to prevent gelation (solidification) under the high temperatures of deep wells.

the adjustment or standardizing of a measuring instrument or of a standard capacity measure, a tank prover, or a pipe prover. Log calibration is based on the use of a permanent calibration facility of the American Petroleum Institute at the University of Houston to establish standard units for nuclear logs.

pulse per unit volume.

in turbine operations, a constant that accounts for the difference between theoretical rotor speed and actual rotor speed.

1. a table that shows the capacities of, or volumes in, a tank for various liquid levels measured from the dip point or from the ullage reference point. Also called gauge or tank capacity table. 2. a table that is developed by recognized industry methods to represent volumes in each tank according to the liquid (innage) or empty space (ullage) measured in the tank. Also called tank capacity table, tank table.

see prover tank.

an instrument with two legs or jaws that can be adjusted for measuring linear dimensions, thicknesses, or diameters.

a record showing variations in wellbore diameter by depth, indicating undue enlargement due to caving in, washout, or other causes. The caliper log also reveals corrosion, scaling, or pitting inside tubular goods.

a device lowered into a wellbore to measure and record the wellbore’s diameter.

an option to buy crude oil for an extended period of time.

catenary anchor leg mooring.

the amount of heat energy necessary to raise the temperature of 1 gram of water 1˚ Celsius. It is the metric equivalent of the British thermal unit.

an apparatus used to determine the heating value of a combustible material.

an eccentrically shaped disk, mounted on a camshaft, that varies in distance from its center to various points on its circumference. As the camshaft is rotated, a set amount of motion is imparted to a follower riding on the surface of the cam. In the internal-combustion engine, cams are used to operate the intake and exhaust valves.

output link of a cam mechanism.

a part of a hydraulic connector that attaches the blowout preventer (BOP) stack to the wellhead and the lower marine riser package (LMRP) to the BOP stack. The cam ring is connected to hydraulic pistons in the connector and the ring’s inside diameter has a 4° taper. When hydraulic locking pressure is applied, the pistons pull the cam ring downward over the locking dogs or segments and the 4° taper forces the dogs or segments inward to lock on the wellhead’s profile.

in drilling from floating rigs that employ a subsea blowout preventer system, a tool used to run the permanent guide base. It allows the drill pipe to be disconnected from the permanent guide base after it lands in the temporary guide base. When the drill pipe is rotated, the cams move into a position that allows the pipe to be removed from the base. See permanent guide base, temporary guide base.

a pressure gauge usually used in lines or manifolds.

the cylindrical bar used to support a rotating device called a cam.

a capacitor whose components are housed inside a small, can-shaped cylinder. See capacitor.

a trade association that represents virtually 100% of the rotary drilling contractors and the majority of well service rig operators in western Canada. The organization concerns itself with research, education, accident prevention, government relations, and other matters of interest to members. Address: 540 5th Avenue SW, Suite 800; Calgary, Alberta, Canada T2P 0M2; (403) 264-4311; fax (403) 263-3796.

a pipeline construction technique used in swamps and marshes. The first of several barges clears the right-of-way and digs a trench large enough to float itself and the following barges.

the fundamental unit of luminous intensity in the metric system.

pertaining to an independent-leg jackup rig designed so that the legs may be slanted outward to increase support against lateral stresses when the unit is on the seafloor.

beams that project outward from a structure and are supported only at one end.

a jackup drilling unit in which the drilling rig is mounted on two cantilevers that extend outward from the barge hull of the unit. The cantilevers are supported only at the barge end. Compare keyway.

(obsolete) a device for sealing the annular space between the top of a liner and the existing casing string.

computer assisted operations.

Canadian Association of Oilwell Drilling Contractors.

to control a well that is flowing out of control; often accomplished by attaching a valve in the open position on top of the well and then closing it to seal off the flow.

to control a blowout by placing a very strong valve on the wellhead. See blowout.

the final welding pass made to complete the uniting of two joints of pipe.

short for gas-cap drive. See gas-cap drive.

natural gas trapped in the upper part of a reservoir and remaining separate from any crude oil, salt water, or other liquids in the well.

1. impermeable rock overlying an oil or gas reservoir that tends to prevent migration of oil or gas out of the reservoir. 2. the porous and permeable strata overlying salt domes that might serve as the reservoir rock.

the ratio of an impressed electrical charge on a conductor to the change in electrical potential; measured in farads. See capacitor.

a device used in most net-oil computers that senses the different dielectric constants of oil and water in a water-oil emulsion. See dielectric constant.

in electronics, the transfer of energy from one circuit to another through a capacitor.

the impedance of current flow in an alternating current circuit (the reactance) caused by a capacitor in the circuit.

an electrical device that, when wired in an electrical circuit, stores a charge of electricity and returns the charge to the line when certain electrical conditions occur. Physically consists of two parallel conductors separated with an insulating material called the dielectric. Its surface area, plate separation, and dielectric constant determine the amount of capacitance in farads. Also called a condenser.

1. volume capability of an electrical capacitor in relation to its ability to store electrical charges. 2. volume capability of a container. 3. in instrumentation and process control, the amount of energy contained in a part of the process. For example, a storage tank stores energy in the form of the weight and the hydrostatic pressure of the liquid it contains. Single capacity systems have only one form of stored energy, while multiple capacity systems have two or more. An example of a multiple capacity system is a tank containing liquid that not only stores energy in the form of hydrostatic pressure, but also stores energy in the form of heat, both of which affect the control process. See capacitance, storage capacity.

a device fitted to a proving tank to indicate the position of the liquid surface in relation to the reference mark corresponding to the nominal capacity of the proving tank, thus enabling the determination of the tank’s liquid contents.

a rating equal to the maximum number of cubic feet of gas that will pass through a meter when the pressure differential across the meter equals a 0.5-inch water column and the flowing pressure is 0.25 psig.

a table that tells the quantity of liquid contained in a tank at any given level.

very small fissures or cracks in a formation through which water or hydrocarbons flow.

the rise and fall of liquids in small-diameter tubes or tubelike spaces, caused by the combined action of surface tension (cohesion) and wetting (adhesion). See capillary pressure.

the liquid seal that reduces slippage between moving parts of a meter.

a pressure or adhesive force caused by the surface tension of water. This pressure causes the water to adhere more tightly to the surface of small pore spaces than to larger ones. Capillary pressure in a rock formation is comparable to the pressure of water that rises higher in a small glass capillary tube than it does in a larger tube.

in accounting, to include expenditures in business accounts as assets instead of expenses.

pertaining to expenditures treated as assets instead of expenses.

a well capable of production but lacking wellhead installations and a pipeline connection.

1. a disklike plate of anhydrite, gypsum, limestone, or sulfur overlying most salt domes in the Gulf Coast region. 2. impermeable rock overlying an oil or gas reservoir that tends to prevent migration of oil or gas out of the reservoir.

1. a small container that holds liquid or gas. 2. a lightweight metal unit to which is attached a single metallic diaphragm. 3. an escape capsule. See escape capsule.

buyers who can purchase natural gas from only one supplier and have no access to alternate fuel sources. This term is usually applicable to residential and small commercial users, but can, under certain conditions of alternative fuel availability, be applied to large industrial and electric utility users as well. Also called core customers.

the tendency of elements in their compounds to reduce energy or number of particles by absorbing them. The more densely populated an area may be, the more certain it is that energy will be absorbed or that the particles will be retained within the atomic structure.

a high-energy gamma ray emitted when the nucleus of an atom captures a neutron and becomes intensely excited. Capture gamma rays are counted by the neutron logging detector.

a naturally abundant nonmetallic element that occurs in many inorganic and in all organic compounds, exists freely as graphite and diamond and as a constituent of coal, limestone, and petroleum, and is capable of chemical self-bonding to form an enormous number of chemically, biologically, and commercially important molecules.

very fine particles of almost pure amorphous carbon, usually produced from gaseous or liquid hydrocarbons by thermal decomposition or by controlled combustion with a restricted air supply. It is used in the manufacture of carbon paper, tires, cosmetics, and so on.

any of several processes for removing excess carbon, usually in the form of carbon dioxide, from the atmosphere to lessen global warming.

a colorless, odorless gaseous compound of carbon and oxygen, CO2. A product of combustion and a filler for fire extinguishers, this heavier-than-air gas can collect in low-lying areas, where it may displace oxygen and present the hazard of anoxia. In contact with steel, it may cause corrosion.

corrosion that occurs when steel is in contact with carbon dioxide and which is characterized by a dark gray scale and pits.

see hypercapnia.

a device that absorbs carbon dioxide (CO2). In the oil industry, it is used to treat exhaust gases from processing plants. In offshore diving, scrubbers remove CO2 from the exhaled air in life support systems.

a colorless, volatile, highly flammable liquid used in solvent extraction processes.

a record that indicates the presence of hydrocarbons by measuring carbon atoms and that reveals the presence of water by measuring oxygen atoms. Oil and water saturations can be closely approximated without the requirement of adequate salinity of known concentration to calculate saturations (as in resistivity and pulsed neutron surveys).

a colorless, odorless gaseous compound of carbon and oxygen, CO. A product of incomplete combustion, it is extremely poisonous to breathe.

in a diesel fuel, the amount of carbon remaining in a special container after the fuel is burned under controlled conditions. Generally, high-quality fuels have low carbon residue.

short for carbon dioxide scrubber. See carbon dioxide scrubber.

a liquid used for degreasing metals; it is toxic when ingested, breathed, or exposed to the skin and is a known carcinogen.

1. a salt of carbonic acid. 2. a compound containing the carbonate radical (CO3). 3. a carbonate rock.

a mud that forms on the seafloor by the accumulation of calcite particles. It may eventually become limestone.

see reef.

formation where oil or gas reside composed primarily of calcium carbonate (limestone) or calcium magnesium carbonate (dolomite).

a sedimentary rock composed primarily of calcium carbonate (limestone) or calcium magnesium carbonate (dolomite); sometimes makes up petroleum reservoirs.

1. a chemical reaction that produces carbonates. 2. in geology, a form of chemical weathering in which a mineral reacts with carbon dioxide (in solution as carbonic acid) to form a carbonate mineral.

of or relating to carbon, carbonic acid, or carbon dioxide.

to convert into carbon or a carbonic residue.

a chemical compound of the aldehyde groups containing a carbonyl group and sulfur, COS. A contaminant in gas liquids, it is usually removed to meet sulfur specifications.

a non­fermenting cellulose product used in drilling fluids to combat contamination from anhydrite (gypsum) and to lower the water loss of the mud.

the mixing of fuel and air in the carburetor of an engine.

the device in a spark-ignition internal-combustion engine in which fuel and air are mixed in controlled quantities and proportions.

to impregnate or combine with carbon.

cancer-causing material or substance.

Conservation Award for Respecting the Environment.

a document that lists the goods or materials carried by a ship, train, airplane, or truck.

a certificate signed by vessel representatives acknowledging the amount of cargo that they intend to load. In general, most product cargoes have a tolerance based on supplier, receiver, or vessel capabilities. Each party involved with the loading agrees to the quantity to be loaded.

see radioactive tracer.

the transportation of a third party’s natural gas by a pipeline as a separate service for a fee, as opposed to the pipeline’s transportation of its own system’s supply of natural gas.

an interest in oil and gas properties that belongs, for example, to a working interest owner or unleased landowner who agrees to a joint operation without being willing to pay a share of the costs of the operation. An interest may be carried until the well pays out, at which point it may stop or may continue for the life of production. Stated another way, an agreement between two or more working interests whereby one party (the carried party) does not share in lease revenue until a certain amount of money has been recovered by the other party (the carrying party). The carrying party pays costs applicable to the carried party’s interests in the property and is reimbursed out of the revenue applicable to the carried party’s interest.

1. a pipeline, trucking company, or marine transportation company that transports oil or gas. 2. on offshore installations with deck grating, a flat or angled length of steel welded to the leading edge of a grated stair that supports the stair tread.

yoke or clamp fastened to a pumping well’s polished rod and to which the bridle of the pumping unit’s horsehead is attached.

term used to refer to a pipeline when other pipe, called casing, is used with it in crossing under roadbeds and railroad rights-of-way. See casing.

a large, specially designed, self-propelled workover rig that is driven directly to the well site. Power from a carrier rig’s hoist engine or engines also propels the rig on the road. While a carrier rig is primarily intended to perform workovers, it can also be used to drill relatively shallow wells. A carrier rig may be a back-in type or a drive-in type. Compare back-in unit, drive-in unit.

see carrier rig.

in the mathematical operation of addition, to perform the necessary actions to obtain a correct answer when the sum of the digits in a given position equals or exceeds the base of the number system. For example, when adding 352 and 49 in the decimal system, 9 is added to 2 in the ones column, which equals 11. In this case, 1 is written below the ones column and the other 1 is added (carried) to the 5 in the tens column of 352, making the 5 a 6. Then, 6 is added to 4 and a 0 placed below the tens column. The 1 is carried to the 3 in the hundreds column, making it 4. The answer is 401.

cam-actuated running tool.

an interest in oil and gas created out of a greater interest and assigned by the owner. Examples are the grant of an overriding royalty interest out of a working interest and the grant of an oil payment out of a working interest.

uses two-stage refrigeration to separate methane from the NGLs.

in systems supplying a breathable source of air to workers wearing breathing equipment in a toxic atmosphere, a serial connection of air cylinders in which the output of air from one adds to that of the next.

the outer cylinder of a concentric cylinder centrifuge. See concentric cylinder centrifuge.

see common law.

hardened (as for a ferrous alloy) so that the surface layer is harder than the interior.

pertaining to a wellbore in which casing has been run and cemented. See casing.

a wellbore in which casing has been run.

the procedure of recovering lost or stuck equipment in a wellbore in which casing has been run.

the difference between inflow and outflow of funds over a period of time. Cash flow can be positive (profit) or negative (loss).

an economic analysis that relates investments to subsequent revenues and also makes possible a comparison between investments. It usually also includes the general plan to be used for the figuring of federal income tax on the investments.

1. steel pipe placed in an oil or gas well to prevent the wall of the hole from caving in, to prevent movement of fluids from one formation to another, and to improve the efficiency of extracting petroleum if the well is productive. Most casing joints are manufactured to specifications established by API, although non-API specification casing is available for special situations. Casing manufactured to API specifications is available in three length ranges. A joint of range 1 casing is 16 to 25 feet (4.8 to 7.6 metres) long; a joint of range 2 casing is 25 to 34 feet (7.6 to 10.3 metres) long; and a joint of range 3 casing is 34 to 48 feet (10.3 to 14.6 metres) long. The outside diameter of a joint of API casing ranges from 4H to 20 inches (114.3 to 508.0 millimetres). Casing is made of many types of steel alloy, which vary in strength, corrosion resistance, and so on. 2. large pipe in which a carrier pipeline is contained. Casing is used when a pipeline passes under railroad rights-of-way and some roads to shield the pipeline from the unusually high load stresses of a particular location. State and local regulations identify specific locations where casing is mandatory.

a swage nipple, usually beveled, installed on the top of a string of pipe that does not extend to the surface. It prevents a smaller string of pipe or tools from hanging up on the top of the column when it is run into the well.

the amount of pressure that, when applied inside a string of casing, causes the wall of the casing to fail. This pressure is critically important when a gas kick is being circulated out, because gas on the way to the surface expands and exerts more pressure than it exerted at the bottom of the well.

a device secured around the casing at regular intervals to center it in the hole. Casing that is centralized allows a more uniform cement sheath to form around the pipe.

a coupling between two joints.

a tubular section of pipe that is threaded inside and used to connect two joints of casing.

the employees of a company that specializes in preparing and running casing into a well. Usually, the casing crew makes up the casing as it is lowered into the well; however, the regular drilling crew also assists the casing crew in its work.

a heavy cylindrical body, fitted with a set of knives, used to free a section of casing in a well. The cutter is run downhole on a string of tubing or drill pipe, and the knives are rotated against the inner walls of the casing to free the section that is stuck.

see elevators.

see float collar.

see float shoe.

a perforating gun run into the casing string. Most perforating guns are run into the well through the tubing string.

a circular device with a frictional gripping arrangement of slips and packing rings used to suspend casing from a casinghead in a well.

in a wellhead, a device that isolates the casing hanger from the inside diameter of the wellhead by means of a metal-to-metal seal. The pack-off keeps pressure from escaping the wellhead from around the casing hanger.

see casing-patch tool.

a means of cementing casing in a well so that the casing may, if necessary, be retrieved with minimum difficulty. A special mud, usually an oil mud, is placed in the well ahead of the cement after the casing has been set. Nonsolidifying mud is used so that it does not bind or stick to the casing in the hole in the area above the cement. Since the mud does not gel for a long time, the casing can be cut above the cemented section and retrieved. Casing packs are used in wells of doubtful or limited production to permit reuse of valuable lengths of casing.

see casing.

1. the depth in a well at which casing is set, generally the depth at which the casing shoe rests. 2. the objective depth in a drilling contract, either a specified depth or the depth at which a specific zone is penetrated. When the depth is reached, the operator makes a decision with respect to running and setting a production string of casing. Under some farmout and letter agreements, some owners are carried to casing point.

the pressure in a well that exists between the casing and the tubing or the casing and the drill pipe.

a short threaded nipple screwed into the open end of the coupling and over the threaded end of casing to protect the threads from dirt accumulation and damage. It is made of steel or plastic. Also called thread protector.

see pipe rack.

a tool composed of a mandrel on which are mounted several heavy-duty rollers with eccentric roll surfaces. It is used to restore buckled, collapsed, or dented casing in a well to normal diameter and roundness. Made up on tubing or drill pipe and run into the well to the depth of the deformed casing, the tool is rotated slowly, allowing the rollers to contact all sides of the casing and restore it to roughly its original condition.

a bladed tool used to scrape away junk or debris from inside casing; it is usually run into the casing on drill pipe or tubing.

a casing sub containing a seal bore and a left-handed thread. It is run as a crossover sub between casing sizes and to provide a tubing anchor.

the location of the bottom of a string of casing that is cemented in a well. Typically, a casing shoe is made up on the end of the casing at this point.

a procedure whereby the formation immediately below the casing shoe is subjected to a pressure equal to the pressure expected to be exerted later by the drilling fluid or by the drilling fluid and the back-pressure created by a kick. See leak-off test.

see guide shoe.

see spider.

a fishing tool designed to grab casing from the inside so that when the spear is retrieved, the attached casing comes with it.

see spider.

a spinning wrench used to rapidly rotate (spin) the male threads of a joint of casing into the female threads of another joint of casing. See spinning wrench.

the entire length of all the joints of casing run in a well. Most wells have more than one string of casing, which are run one inside the other as drilling progresses. Generally, wells have a length, or string, of surface casing, intermediate casing, and production casing, although a great deal of variation occurs according to a well’s depth, the formations it penetrates, and other factors. See casing, intermediate casing, production casing, surface casing.

a sub used to join two dissimilar joints of casing.

a solid cylindrical body pointed at the bottom and equipped with a tool joint at the top for connection with a jar. It is used to make an opening in a collapsed casing and drive it back to its original shape.

large wrench used for turning when making up or breaking out casing. See tongs.

to cement casing in a well in a way that allows for easy retrieval of sections of casing. See casing pack.

a special tool with a rubber packer or lead seal that is used to repair casing. When casing is damaged downhole, a cut is made below the damaged casing, the damaged casing and the casing above it are pulled from the well, and the damaged casing is removed from the casing string. The tool is made up and lowered into the well on the casing until it engages the top of the casing that remains in the well, and a rubber packer or lead seal in the tool forms a seal with the casing that is in the well. The casing-patch tool is an overshot-like device and is sometimes called a casing overshot.

usually high-capacity shear rams capable of shearing drill collars and casing strings that are installed below the blind-shear rams in a BOP stack. Casing-shear rams can be used in addition to the blind-shear rams to shear pipe. See shear ram.

in a wellbore, the space between the inside of the casing and the outside of the tubing.

a heavy, flanged steel fitting connected to the first string of casing. It provides a housing for slips and packing assemblies, allows suspension of intermediate and production strings of casing, and supplies the means for the annulus to be sealed off. Also called a spool. See annular space.

gas produced with oil.

a contract used by industry for the purchase and sale of casinghead gas.

(obsolete) natural gasoline.

1. short for an industrial or gas engine manufactured by Caterpillar, Inc. 2. short for any piece of industrial equipment, such as a bulldozer, manufactured by Caterpillar, Inc.

gas that is a by-product of refining liquid hydrocarbons in a catalytic cracker.

short for catalytic cracking. See catalytic cracking.

see nominal strength.

a substance that alters, accelerates, or instigates chemical reactions without itself being affected.

processes used to reduce the toxicity of emissions.

1. the breaking down of heavier hydrocarbon molecules into lighter hydrocarbons using catalysts and relatively low temperatures and pressures. 2. a motor gasoline refining process in which heavy hydrocarbon components are broken down into light hydrocarbon components using catalysts and relatively low temperatures and pressures. It produces a gasoline that has a higher octane rating and a lower sulfur content than that produced by thermal cracking.

the theory that the earth’s landforms assumed their present configuration in a brief episode at the beginning of geologic history-possibly in a single great catastrophic event-and have remained relatively unchanged since that time. Compare uniformitarianism.

to obtain cuttings for geological information as formations are penetrated by the bit. The samples are obtained from drilling fluid as it emerges from the wellbore or, in cable-tool drilling, from the bailer. Cuttings are carefully washed until they are free of foreign matter, dried, and labeled to indicate the depth at which they were obtained.

a device fitted into a junk basket that retains the junk picked up by the basket.

a category of actions that do not individually or cumulatively have a significant effect on the human environment and that have been found to have no such effect in procedures adopted by a federal agency when implementing NEPA regulations. Therefore, neither an environmental assessment nor an environmental impact statement is required.

1. the curve assumed by a perfectly flexible line hanging under its own weight between two fixed points. A suspension bridge is an example of a catenary structure; an anchor chain is a catenary. 2. the part of a mooring leg suspended between a rig and the seafloor.

a type of offshore mooring in which the facility is anchored by at least six anchors; it generally has no storage facility.

on floating offshore production platforms, a flexible metal pipe-a riser-that conducts well fluids from the subsea wellhead to production facilities on the platform. On the platform at the water’s surface, buoyant air cans or tensioning devices support the riser. The riser is flexible enough to assume a catenary shape when deployed. That is, the riser runs vertically into the water but turns to lie flat on the seafloor, roughly in the shape of a J. As the platform heaves, the riser flexes. See catenary.

multileg spread mooring using components in a pure catenary configuration.

a spool-shaped attachment on the end of the catshaft, around which rope for hoisting and moving heavy equipment on or near the rig floor is wound. See breakout cathead, makeup cathead.

see cathead.

1. one of two electrodes in an electrolytic cell, represented as the positive terminal of a cell. 2. in cathodic protection systems, the protected structure that is representative of the cathode and is protected by having a conventional current flow from an anode to the structure through the electrolyte. 3. the terminal of a semiconductor diode that is negative with respect to the other terminal when the diode is biased in the forward direction. See diode.

a stream of electrons, such as those emitted by a heated filament in a tube, or those emitted by the cathode of a gas-discharge tube when the cathode is bombarded by positive ions.

an electron tube in which a bean of electrons can be focused to a small area and varied in position and intensity on a surface.

used to measure the deterioration of steel structures under water. Also called bathycorrometers.

cathodic potential survey outcomes that engineers review to determine if the sacrificial anodes are performing to prevent electrical current in the water from corroding and deteriorating the structure.

a method of protecting a metal structure from corrosion by making its surfaces cathodic and controlling the location of anodic areas so that corrosion damage can be reduced to tolerable levels.

a positively charged ion; the ion in an electrolyzed solution that migrates to the cathode. See ion. Compare anion.

a hoisting or pulling line powered by the cathead and used to lift heavy equipment on the rig. See cathead.

an axle that crosses through the drawworks and contains a revolving spool called a cathead at either end. See cathead.

1. the ramp at the side of the drilling rig where pipe is laid to be lifted to the derrick floor by the catline or by an air hoist. See catline. 2. any elevated walkway.

see caustic soda. adj: capable of burning, corroding, dissolving, or eating away by chemical action such as with caustic soda, made of sodium hydroxide, which is used to maintain an alkaline pH in drilling mud and petroleum fractions. See corrosion.

see alkaline (caustic) flooding.

sodium hydroxide, NaOH. It is used to maintain an alkaline pH in drilling mud and in petroleum fractions.

a vessel holding sodium hydroxide or other alkalis through which a solution flows for removal of sulfides, mercaptans, or acids. See regenerative process.

the collapse of the walls of the wellbore.

a natural cavity in the earth’s crust that is large enough to permit human entry. Commonly formed in limestone by groundwater leaching. Compare vug.

a rock formation that contains large open spaces, usually resulting from the dissolving of soluble substances by formation waters that may still be present. See vug.

collapsing of the walls of the wellbore. Also called sloughing.

particles that fall off (are sloughed from) the wall of the wellbore. Compare cuttings.

the formation and collapse of vapor- or gas-filled cavities that result from a sudden decrease and increase of pressure. Cavitation can cause mechanical damage to adjacent surfaces in meters, valves, pumps, and pipes at locations where flowing liquid encounters a restriction or change in direction.

a hollow area or a hole within the body of a piece of equipment, a device, or a rock.

cumulonimbus.

circulating bottomhole temperature.

cement bond log.

cirrocumulus.

cubic centimetre.

cold cranking ampere.

casing collar log.

carbon capture and sequestration.

candela.

the height above the ground up to the base of the lowest layer of clouds when over half the sky is obscured.

the maximum lawful price that may be charged for the first sale of a specified NGPA category of natural gas.

a device that delivers an electric current as the result of a chemical reaction; a receptacle, such as a jar, tube, or box, that contains two dissimilar metals immersed in or surrounded by a liquid or solid chemical (an electrolyte) that reacts with both metals.

a pit in the ground, usually lined with concrete, steel pipe, or wood, that provides additional height between the rig floor and the wellhead to accommodate the installation of blowout preventers, rathole, mousehole, and so forth. It also collects drainage water and other fluids for subsequent disposal.

the lower deck of a double-decked semisubmersible drilling rig. See main deck, Texas deck.

a thin, transparent material made from cellulose and used as a lost circulation material. See cementing materials.

any derivative of cellulose-for example, cellulose acetate is a cellulosic.

the metric scale of temperature measurement used universally by scientists. On this scale, 0° represents the freezing point of water and 100° its boiling point at a barometric pressure of 760 mm. Degrees Celsius are converted to degrees Fahrenheit by using the following equation: °F = 9/5 (°C) + 32 or °F = 1.8 (°C) + 32.  The Celsius scale was formerly called the centigrade scale; now, however, the term “Celsius” is preferred in the International System of Units (SI).

a powder consisting of alumina, silica, lime, and other substances that hardens when mixed with water. Extensively used in the oil industry to bond casing to the walls of the wellbore.

a material added to cement to change its properties. Chemical accelerators, chemical retarders, and weight-reduction materials are common additives. See cementing materials.

the adherence of casing to cement and cement to formation. When casing is run in a well, it is set, or bonded, to the formation by means of cement.

an acoustic logging method based on the fact that sound travels at different speeds through materials of different densities. The fact that sound travels faster through cement than through air can be used to determine whether the cement has bonded properly to the casing.

an acoustic survey or sonic-logging method that records the quality or hardness of the cement used in the annulus to bond the casing and the formation. Casing that is well bonded to the formation transmits an acoustic signal quickly; poorly bonded casing transmits a signal slowly. See acoustic survey, acoustic well logging.

to fill the annulus between the casing and wall of the hole with cement to support the casing and prevent fluid migration between permeable zones.

when casing is being cemented in a borehole, the cement slurry can fail to rise uniformly between the casing and the borehole wall, leaving spaces devoid of cement. Ideally, the cement should completely and uniformly surround the casing and form a strong bond to the borehole wall.

a substance formed by melting ground limestone, clay or shale, and iron ore in a kiln. Cement clinker is ground into a powdery mixture and combined with small amounts of gypsum or other materials to form cement.

a cylindrical container with a valve used to release small batches of cement in a remedial cementing operation.

reaction with water that begins when water is added to powdered cement. The cement gradually sets to a solid as hydration continues.

1. a portion of cement placed at some point in the wellbore to seal it. 2. a wiper plug. See cementing, wiper plug.

a tool set temporarily in the casing or well to prevent the passage of cement, thereby forcing it to follow another designated path. It is used in squeeze cementing and other remedial cementing jobs.

a particular slurry containing cement and water, with or without additives.

1. the crystallization or precipitation of soluble minerals in the pore spaces between clastic particles, causing them to become consolidated into sedimentary rock. 2. precipitation of a binding material around grains or minerals in rocks.

a retrievable cement squeeze tool that is used in remedial cementing. See remedial cementing, secondary cementing.

the application of a liquid slurry of cement and water to various points inside or outside the casing. See primary cementing, secondary cementing, squeeze cementing.

a barge containing the cementing pumps and other equipment needed for oilwell cementing in water operations.

a collapsible or folding metal cone that fits against the walls of the wellbore to prevent the passage of cement; sometimes called a metal-petal basket.

a company whose specialty is preparing, transporting, and pumping cement into a well. Usually, a cementing company’s crew pumps the cement to secure casing in the well.

an accessory attached to the top of the casing to facilitate cementing of the casing. It has passages for cement slurry and retainer chambers for cementing wiper plugs. Also called retainer head.

a slurry of portland cement and water and sometimes one or more additives that affect either the density of the mixture or its setting time. The portland cement used may be high early strength, common (standard), or slow setting. Additives include accelerators (such as calcium chloride), retarders (such as gypsum), weighting materials (such as barium sulfate), lightweight additives (such as bentonite), or a variety of lost circulation materials (such as mica flakes).

a high-pressure pump used to force cement down the casing and into the annular space between the casing and the wall of the borehole.

the total elapsed time needed to complete a cementing operation.

the time period from 65 million years ago until the present. It is marked by rapid evolution of mammals and birds, flowering plants, grasses, and shrubs, and little change in invertebrates.

a condition on a bit in which the inside row of cutters on the cones wears or breaks or the nose of one or more of the cones breaks.

in a chain-and-sprocket drive, the distance between the centers of the two sprockets or the shafts they fit on.

on roller cone bits, especially those designed for drilling soft, sticky formations, an additional jet nozzle that is added above the cones and in the middle of the bit. In some cases, the center jet, in addition to the three jets on the sides of the bit, can help keep the bit cutters clean.

the center of gravity of the fluid displaced by a floating body (such as a ship or mobile offshore drilling rig).

the geometric center of the water plane at which a mobile offshore drilling rig floats and about which a rig rotates when acted on by an external force without a change in displacement.

the point at which an object can be supported so that it balances, and at which all gravitational forces on the body and the weight of the body are concentrated; the center of mass.

the point at which all wind pressure forces are concentrated.

vertical pin or shaft which acts as a rotation centering device and connects the revolving superstructure and base mounting; also called center pintle or center post.

a barbed fishing tool used to snag and retrieve broken wireline from the wellbore.

elevators that have the handles and latch arranged so that when a crew member opens the latch, they part in the middle. Compare side-door elevators. See elevators.

the middle line of the hull of a mobile offshore drilling rig from stem to stern, as shown in a waterline view.

see Celsius scale.

a unit of length in the SI metric system equal to one-hundredth of a metre (10–2 metre).

a variant of the SI metric system in which the measures are founded on the centimetre, gram, and second rather than directly on the kilogram and metre.

one-hundredth of a poise; a measure of a fluid’s viscosity, or resistance to flow.

an installation serving two or more leases and providing one or more of such functions as separation, compression, dehydration, treating, gathering, or delivery of gas and oil.

that part of the human body’s nervous system that consists of the brain and spinal cord.

a processing network used to treat emulsion produced from several leases, thus eliminating the need for individual treating facilities at each lease site.

in computer technology, the electronic device that contains the circuits necessary to receive, interpret, and carry out instructions received from peripherals such as keyboards, monitors, hard drives, and the like.

see casing centralizer.

a compressor in which the flow of gas to be compressed is moved away from the center rapidly, usually by a series of blades or turbines. It is a continuous-flow compressor with a low-pressure ratio and is used to transmit gas through a pipeline. Gas passing through the compressor contacts a rotating impeller, from which it is discharged into a diffuser, where its velocity is slowed and its kinetic energy changed to static pressure. Centrifugal compressors are nonpositive-displacement machines, often arranged in series on a line to achieve multistage compression.

a device for removing entrained gas from drilling mud in which a vacuum pump draws mud into degassing tubes inside the device. The tubes spin to create centrifugal force, which disperses the mud into thin layers on the wall of the tubes. A vacuum then pulls gas out inside an expansion tank.

the force that tends to pull all matter from the center of a rotating mass.

a pump with an impeller or rotor, an impeller shaft, and a casing, which discharges fluid by centrifugal force. An electric submersible pump is a centrifugal pump.

see centrifugal compressor.

a machine that uses centrifugal force to separate substances of varying densities. A centrifuge is capable of spinning substances at high speeds to obtain high centrifugal forces. Also called the shake-out or grind-out machine.

a test to determine the amount of S&W in samples of oil or emulsion. The samples are placed in tubes and spun in a centrifuge, which breaks out the S&W.

Council on Environmental Quality.

Comprehensive Environmental Response, Compensation, and Liability Act of 1980.

a certificate of public convenience and necessity issued under the Natural Gas Act.

any natural gas that has a certificate issued and that in effect is transported by an interstate pipeline.

an individual who has applied for and been awarded a certification card or other document recognized to reflect the formal training, field experience, on-the-job performance, and capabilities, of the individual.

a copy made from records in a recorder’s or county clerk’s office and certified to by the recorder or county clerk as being an exact copy of the paper on file or of record.

(slang) certifications of materials on physical and chemistry properties.

a clause in an oil and gas lease that provides the lessee with the right to begin new operations within a stated time period should production cease.

a measure of the ignition quality of fuel oil. The higher the cetane number, the more easily the fuel is ignited.

cubic feet of gas; used in drilling reports.

1. Code of Federal Regulations. 2. Coordinating Fuels and Equipment Research Committee.

in offshore drilling, a heavy line constructed of iron bars looped together and used for a mooring line.

see chain drive.

see chain guard.

a mechanical drive using a driving chain and chain gears to transmit power. Power transmissions use a roller chain, in which each link is made of side bars, transverse pins, and rollers on the pins. A double roller chain is made of two connected rows of links, a triple roller chain of three, and so forth.

in a chain-and-sprocket drive, a case that protects workers from the moving drive. It also protects the drive from dirt and is part of the cooling and lubrication systems. Some enclose only one drive and some enclose several drives. May be made of sheet metal or plate metal. Heavier guards also support the shafts on bearings. Both types have access panels for inspection and maintenance.

a compartment on a rig (usually located in a column) used to store mooring chain.

recorded transfers (links) in title from patent to present.

a reduction unit between a prime mover and a beam pumping unit that reduces the prime mover’s output speed by means of a series of chains.

a device on a rig that locks off a chain mooring and takes the mooring line tension in the survival condition.

a steel component inserted into the center of a chain link. The stud may or may not be welded to the link.

a hand tool consisting of a handle and chain that resembles the chain on a bicycle. In general, chain tongs are used for turning pipe or fittings of a diameter larger than that which a pipe wrench would fit. The chain is looped and tightened around the pipe or fitting, and the handle is used to turn the tool so that the pipe or fitting can be tightened or loosened.

the part of a chain windlass that holds the weight of the chain during heave in or payout.

in roller chain, the width of the rollers, which is the distance between the inside faces of the roller link plates.

see chain whelp.

a type of drive that consists of a loop of chain that goes around two shafts with sprockets fitted on the shafts. The driving shaft provides power and the driven shaft receives power. When the sprocket on the driving shaft turns, the chain moves and turns the driven sprocket.

a selective transmission made up primarily of chain-and-sprocket drives. There are three two-strand chain-and-sprocket drives and a pair of gears for reversing, located between the input shaft coming from the compound, and the output shaft on a mechanically driven drawworks. Each of these chain-and-sprocket drives has a different sprocket ratio to provide three speeds to the high-drum drive and three to the low-drum drive. Compare gear transmission.

a specialized form of intermittent-flow gas lift that functions in the same way as other forms, except that, when the injection gas is off, incoming well fluids accumulate in a chamber having a larger diameter than the tubing. For the same volume of fluid, hydrostatic head and wellbore pressure at the formation are both reduced.

a small building, or doghouse, in which members of a drilling rig or roustabout crew change clothes, store personal belongings, and so on.

the difference between initial and final heel caused by a load change in the port-to-starboard or starboard-to-port direction.

the difference between the initial and final trim caused by a load change in the forward or aft direction. See trim.

to take rams out of a blowout preventer and replace them with rams of a different size or type. When the size of a drill pipe is changed, the size of the pipe rams must be changed to ensure that they seal around the pipe when closed (unless variable-bore pipe rams are in use).

the main current path between the source and drain electrodes in a field-effect transistor.

1. when casing is being cemented in a borehole, the cement slurry can fail to rise uniformly between the casing and the borehole wall, leaving spaces, or channels, devoid of cement. Ideally, the cement should completely and uniformly surround the casing and form a strong bond to the borehole wall. 2. the bypassing of oil in a water-drive field due to erratic or uncontrolled water encroachment. The natural tendency toward channeling is aggravated by excessive production rates, which encourage premature water encroachment. See cement channeling.

a vessel filled with charcoal, which absorbs chemical contaminants such as condensates and well treatment chemicals from the glycol stream.

a test standardized by the American Gas Association and the Gas Processors Association for determining the natural gasoline content of a given natural gas. The gasoline is adsorbed from the gas on activated charcoal and then recovered by distillation. The test is described in Testing Code 101–43, a joint AGA and GPA publication.

oil that is to be treated in, or charged to, a particular refinery unit.

an ideal gas law that states that at constant pressure the volume of a fixed mass or quantity of gas varies directly with the absolute temperature; that is, at a constant pressure, as temperature rises, gas volume increases proportionately.

in metallurgy, a test used to determine a material’s ability to deform under tensile stress (its ductility). A notched specimen is loosely placed on a support and a freely swinging pendulum is allowed to strike and break the specimen. The amount of force it took for the pendulum to break the specimen is determined by comparing the position of the pendulum before it was released with the position to which it swings after it broke the specimen. The more force required to break the material, the higher is the material’s ductility.

part of a company that interprets and processes the information obtained from the orifice meter charts. The department’s responsibilities include calculating the gas flow from the information on the chart. Today, charts have been largely supplanted by electronic readouts generated by computer controlled sensors at the orifice meter station. These readouts are transmitted to the company’s computers in a central, or district, office, where they are recorded and read.

an agreement by which a shipowner agrees to place an entire ship, or part of it, at the disposal of a merchant or other person to carry cargo for an agreed-upon sum.

to lower the drill stem rapidly a few feet into the hole and then stop it suddenly with the drawworks brake. A surge of pressure in the mud in the drill stem and annular space results and may help to flush out debris accumulated in or on the pipe. The pressure surge may break down a formation, however, causing lost circulation, or may damage the bit if it is near the bottom.

to clean and deburr the threads of a pipe so that it will make up properly.

the framework to which the components of a radio, television, or other electronic equipment are attached.

a phenomenon in which the cutters of a bit, while rotating on bottom, do not adequately penetrate the formation; instead, the cutters tend to bounce off the formation. The bounce is sometimes transmitted to the drill stem in the form of a vibration, or chatter.

a length of pipe fitted over a wrench handle to increase the leverage of the wrench. Use of a larger wrench is usually preferred. Also called a snipe.

a device for measuring gas throughput, usually installed in conjunction with the primary measuring device owned and operated by the party having the obligation to provide measurement services at a specific point on a pipeline system.

a valve that permits fluid to flow in one direction only. If the gas or liquid starts to reverse, the valve automatically closes, preventing reverse movement. Sometimes referred to as a one-way valve.

an agreement for the acquisition of mineral rights (i.e., oil and gas leases) in a checkerboard pattern of alternate tracts, usually beginning, in the case of farmouts, with the drill site tract.

slight breaks in the surface of a paint film that do not render the underlying surface visible when the film is viewed at a magnification of ten times. Types include irregular pattern checking in which the breaks do not have a definite pattern, line checking in which the breaks are generally parallel, and crow-foot checking in which the breaks assume a three-pronged shape and the prongs radiate from a point at an angle of about 120 degrees.

a means of examining or inspecting a device or a system by reading a list of items and, after reading each item, verifying that action has been taken to complete the inspection.

any class of complex compounds consisting of a central metal atom chemically bonded to a large molecule. More stable than nonchelated compounds of comparable composition.

a brand name for an electrostatic treater.

a substance defined under HAZCOM (OSHA) as any element, chemical compound, or mixture of elements and/or compounds.

in removing contaminants, the liquid absorbent reacts chemically with the acid gases but not with the natural gas.

a container in which various chemicals are mixed prior to addition to drilling fluid.

the procedure by which a quantity of resinous material is squeezed into a sandy formation to consolidate the sand and to prevent its flowing into the well. The resinous material hardens and creates a porous mass that permits oil to flow into the well but holds back the sand at the same time. See sand consolidation.

a method of severing steel pipe in a well by applying high-pressure jets of a very corrosive substance against the wall of the pipe. The resulting cut is very smooth.

a fishing tool that uses high-pressure jets of chemicals to sever casing, tubing, or drill pipe stuck in the hole.

the process of tracking down the source of an illegal waste discharge through sampling the waste and possible sources to determine which source matches the discharge best. Fingerprinting is expensive, but in large damage cases, it can help prove or disprove whether a substance was discharged from a particular source.

see alkaline (caustic) flooding, micellar-polymer flooding.

liquid chemical compounds that are injected into lines carrying fluids that contain H2S. Most of these inhibitors are designed to coat equipment surfaces to physically isolate them from corrosive substances. Others react with sulfur compounds to form less-destructive compounds.

a valve on the wellhead of a producing well that is usually installed between the production master valve and production wing valves. A chemical injection line leading into the well exits from the valve and goes into the well. The chemical injection valve isolates the chemical injection line from the surface.

an inventory required by HAZCOM. Under HAZCOM, all employers must keep a complete list, or inventory, of all hazardous materials on site.

capable of being mixed with chemicals. See miscible.

clothing that is designed to protect against a specific chemical hazard (i.e., suits or aprons made of or coated with chemical-resistant materials like butyl rubber, neoprene, or polyvinyl chloride).

an injection pump used to introduce a chemical into a fluid stream or receptacle.

a change in which a substance or substances is changed into one or more substances.

any of many processes in the oil industry that involve the use of a chemical to effect an operation. Some chemical treatments are acidizing, crude oil demulsification, corrosion inhibition, paraffin removal, scale removal, drilling fluid control, refinery and plant processes, cleaning and plugging operations, chemical flooding, and water purification.

in drilling-fluid terminology, a chemical is any material that produces changes in the viscosity, yield point, gel strength, fluid loss, and surface tension.

a rock of precipitated silica whose crystalline structure is not easily discernible and that fractures conchoidally (like glass). Flint, jasper, and chat are forms of chert.

a long steel pole with a hook on one end that allows one of the rotary helpers to release the safety latch on the drilling hook so that the bail of the swivel can be removed (as when the kelly is set back prior to making a trip). Also called a shepherd’s stick, or hook.

a flexible coupling used in high-pressure lines. Sometimes called Chicksan.

a heat exchanger that cools process fluids with a refrigerant.

1. the shaped and processed semiconductor die that is mounted on a substrate to form a transistor, diode, or other semiconductor device. 2. an integrated microcircuit performing a significant number of functions and constituting a subsystem.

the holding of formation rock chips in place as a result of high differential pressure in the wellbore (i.e., pressure in the wellbore is greater than pressure in the formation). This effect limits the cutting action of the bit by retarding circulation of bit cuttings out of the hole.

the removal of paint and surface contaminants from a substrate by means of impact from a sharpened tool.

see cuttings.

choke; used in drilling reports.

a greenish-yellow, acrid gas (Cl) that irritates the skin and mucous membranes and causes breathing difficulties.

a record of the presence and concentration of chlorine in oil reservoirs. See chlorine survey.

a special type of radioactivity-logging survey used to measure the relative amount of chlorine in the formation. Rocks with low chlorine content are likely to contain gas or oil; rocks with high chlorine content usually contain salt water only.

a fitting or fixture used to restrict movement, especially movement of a line.

1. a device with an orifice installed in a line to restrict the flow of fluids. Surface chokes are part of the Christmas tree on a well and contain a choke nipple, or bean, with a small-diameter bore that serves to restrict the flow. Chokes are also used to control the rate of flow of the drilling mud out of the hole when the well is closed in with the blowout preventer and a kick is being circulated out of the hole. See adjustable choke, bottomhole choke, positive choke. 2. in electronics, an inductance used in a circuit to present high impedance to frequencies above a specified frequency range without appreciably limiting the flow of direct current.

an assembly of lines (pipes), valves, and operating devices (a system) on a subsea blowout preventer that provides a conduit for drilling mud to be pumped into the well through a kill line and a conduit for fluids exiting from the well to flow through a choke line to the surface. See choke line, kill line.

a device that, when opened, allows drilling mud to be pumped into the well and drilling and other fluids returning from the well to be directed to the choke manifold on the surface. See choke line, kill line.

the drop in pressure that occurs when fluid flows through the choke and separator on a drilling or workover rig. The drop is caused by friction as the fluid contacts the sides of the choke and the separator; also, friction within the flowing fluid itself causes a pressure loss.

in crane operations, the angle between the vertical part and choked part of a choker sling. As this angle decreases, the load-lifting capacity of the sling also decreases. See choker sling.

a device placed in a choke line that regulates the flow through the choke. Flow depends on the size of the opening in the bean; the larger the opening, the greater the flow.

a panel or board on the rig floor, usually near the driller’s position, that allows a person to remotely adjust the size of the opening of a choke installed in the choke manifold. By adjusting the choke’s opening, the operator can increase or decrease the amount of back-pressure being held on the well by the choke. Usually, the panel also has pressure gauges and other instruments to help the operator control the well.

see critical flow.

see choke line.

a pipe, or conduit, usually installed on outlets below the ram blowout preventers, through which fluids in the annulus can flow to the surface and through the choke manifold when valves to it are open. On floating offshore rigs, flow may be directed either down the annulus or up the annulus; on most land rigs, flow is only upward.

an arrangement of piping and special valves, called chokes. In drilling, mud is circulated through a choke manifold when the blowout preventers are closed. In well testing, a choke manifold attached to the wellhead allows flow and pressure control for test components downstream. See choke and blowout preventer.

see bean.

see back-pressure.

in crane operations, a method of attaching a sling to a load in which one end of the sling is passed around the load, through an attachment or an eye on the other end, and then to the crane’s hook. As the load is lifted by the crane, the hitch tightens on the load.

a wire rope sling that forms a slip noose around an object to be moved or lifted by a crane.

the control valves, pressure gauges, and chokes assembled at the top of a well to control the flow of oil and gas after the well has been drilled and completed. It is used when reservoir pressure is sufficient to cause reservoir fluids to flow to the surface.

a compound in which chromium has a valence of 6, e.g., sodium bichromate. Chromate may be added to drilling fluids either directly or as a constituent of chrome lignites or chrome lignosulfonates. In certain areas, chromate is widely used as a corrosion inhibitor, often in conjunction with lime.

an analytical instrument that separates mixtures of substances into identifiable components by means of chromatography.

a laboratory analysis of a gas sample to determine the composition of the gas. The analysis will determine the percentage of each component of the gas; this percentage can be used to calculate liquid volume percentage, GPMs, Btu, and gravity.

a method of separating a solution of closely related compounds by allowing it to seep through an adsorbent so that each compound is adsorbed in a separate layer.

mined lignite, usually leonardite, to which chromate has been added or has reacted. The lignite can also be causticized with either sodium or potassium hydroxide.

a chemical element whose symbol is Cr and that has an atomic number of 24. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable. The name of the element comes from the Greek word for color, chroma, which means color, because many of its compounds are intensely colored. In drilling fluids, compounds of chromium, such as sodium bichromate, are added to prevent corrosion.

cirrus.

concrete island drilling system.

circulated; used in drilling reports.

in diamond bits, a pattern of setting diamonds in which the manufacturer spreads them in concentric circles on the cutting surface (the nose) of the bit. Compare grid plot.

see wheel-type back-off wrench.

a complete electrical path from one terminal of a source of electricity to the other, usually connected to a load. When the circuit is closed, electric current flows through it; when it is opened, the current flow stops.

see schematic.

the cross-sectional area of a wire or cable expressed in thousandths of an inch (a milli-inch).

a metering instrumentation system component that counts the revolutions of the index shaft.

to pass from one point throughout a system and back to the starting point. For example, drilling fluid is circulated out of the suction pit, down the drill pipe and drill collars, out the bit, up the annulus, and back to the pits while drilling proceeds.

see reverse circulation.

see concurrent method.

an external gripping tool that allows direct circulation through the tool and the fish to keep the wellbore lubricated during fishing. See overshot.

the equipment included in the drilling fluid circulating system of a rotary rig. Basically, the components consist of the mud pump, the rotary hose, the swivel, the drill stem, the bit, and the mud return line.

see equivalent circulating density.

see drilling fluid, mud.

an accessory attached to the top of the drill pipe or tubing to form a connection with the mud system to permit circulation of the drilling mud. In some cases, it is also a rotating head.

the pressure generated by the mud pumps and exerted on the drill stem.

the volume flow rate of the circulating drilling fluid usually expressed in gallons or barrels per minute in the United States. Elsewhere, it is expressed in cubic metres per minute.

responsible for getting mud down the hole through drill pipe and drill collars, jetting mud through the bit so it can pick up cuttings, and carrying cuttings to the surface.

the movement of drilling fluid out of the mud pits, down the drill stem, up the annulus, and back to the mud pits. See normal circulation, reverse circulation.

see sliding sleeve.

a variation of squeeze cementing for wells with two producing zones in which (1) the upper fluid sand is perforated; (2) tubing is run with a packer, and the packer is set between the two perforated intervals; (3) water is circulated between the two zones to remove as much mud as possible from the channel; (4) cement is pumped through the channel and circulated; (5) the packer is released and picked up above the upper perforation, a low squeeze pressure is applied, and the excess cement is circulated out. The process is applicable where there is communication behind the pipe between the two producing zones because of channeling of the primary cement or where there is essentially no cement in the annulus.

an accessory employed above a packer, to permit annulus-to-tubing circulation or vice versa.

a white high-level cloud that is composed primarily of ice crystals. This type of cloud forms from cirrus or cirrostratus clouds and has a rippled appearance.

a very thin, white, high-level cloud that produces halos visible around the sun or moon. This type of cloud is composed of ice crystals and appears as a thin veil in the sky.

a high-level, white, feather­like cloud that is composed of ice crystals.

an atmospheric pressure measuring device (a barometer) that is made up of an evacuated glass tube (about 1 yard or 1 metre in length) that is completely filled with mercury and an open dish (exposed to the atmosphere) that is partially filled with mercury. When the open end of the tube is placed in the dish, the mercury in the tube falls to a height equivalent to the atmospheric pressure.

notations that appear in government documents for cross-referencing information. If you are reading a regulation that refers to another regulation or to a different section in the same regulation, the citation will be listed so that you may refer to the appropriate material for more information.

see city gate station.

a station to which a transmission company delivers gas to the distribution company. This is the point at which interstate and intrastate pipelines sell and deliver gas to local distribution companies. Usually built adjacent to a natural gas transmission line in a sparsely populated area on the outskirts of a population center. Also called city gas station, town border station.

chemical injection valve.

see statute law.

penalties for damages to private individuals or organizations typically determined by a court decision on suits filed against private individuals or corporations.

chlorine.

(slang) commonly used to describe moderate to severe flocculation of mud due to various contaminants. Also called gelled-up.

in electronics, braided or solid aluminum or other material that surrounds insulated wires or cables. Cladding protects the wire or cable from being damaged by blows or forces from external sources, such as dropped objects, foot traffic, and the like.

a mechanical device used to hold an object in place. For example, a leak-repair clamp, or saddle clamp, holds a piece of metal with the same curvature as the pipe over a hole in a line, effecting a temporary seal. A wireline clamp holds the end of a wire rope against the main rope, while a polished-rod clamp attaches the top of the polished rod to the bridle of a pumping unit.

an AC voltmeter-ammeter that has a magnetic core in the form of hinged jaws that can be clamped around a current-carrying wire to measure AC voltage or amperage. Also called a snap-on meter.

a classification of injection wells under the Safe Drinking Water Act that are related to hazardous, industrial nonhazardous, and municipal wastewater disposal below underground sources of drinking water.

a classification of injection wells under SDWA that is related to oil and gas activity. Typically, these wells are used to dispose of produced waters into depleted oil formations below drinking water sources; to inject produced water from production operations back into the producing zone; to inject fluids for enhanced recovery; and to store hydrocarbons.

a sedimentary rock composed of fragments of preexisting rocks. The principal distinction among clastics is grain size. Conglomerates, sandstones, and shales are clastic rocks.

rock texture in which individual rock, mineral, or organic fragments are cemented together by an amorphous or crystalline mineral such as calcite. Compare crystalline texture.

1. sediments formed by the breakdown of large rock masses by climatological processes, physical or chemical. 2. the rocks formed from these sediments.

see Claus process.

a process to convert hydrogen sulfide into elemental sulfur by selective oxidation. The Claus process has become the industry standard since its invention more than 100 years ago.

see Claus process.

see tail gas.

1. a term used for particles smaller than 1/256 millimetre (4 microns) in size, regardless of mineral composition. 2. a group of hydrous aluminum silicate minerals (clay minerals). 3. a sediment of fine clastics.

any of several substances-usually organic compounds of high molecular weight-that, when added in low concentrations to a bentonite or to certain other clay slurries, will increase the viscosity of the system. See low-solids mud.

the swelling that occurs when clays in the formation take on water.

the number of barrels of a liquid slurry of a given viscosity that can be made from a ton of clay. Clays are often classified as either high- or low-yield. A ton of high-yield clay yields more slurry of a given viscosity than a low-yield clay.

one of the first environmental laws passed by the federal government. The CAA addresses and regulates airborne pollution that may be potentially hazardous to public health or natural resources.

ballast that is free of any measurable quantity of hydrocarbon.

to remove sand, scale, and other deposits from the producing section of the well to restore or increase production.

law that regulates the discharge of toxic and nontoxic pollutants into the surface waters of the United States. Under the jurisdiction of both the EPA and the Army Corps of Engineers, CWA’s short-term goal is to make surface waters safe for recreation, fishing, and other uses. Its long-term goal is to eliminate all harmful discharges into surface waters.

(under HAZWOPER) an operation during which hazardous substances are removed, contained, incinerated, neutralized, stabilized, cleaned up, or in any other manner processed or handled, with the ultimate goal of making the site safer for people or the environment.

a self-propelled machine with a rotating set of brushes and buffers that removes from pipe surface any loose material and applies a thin coat of primer to prepare the pipe for coating.

an opening made to permit removal of sediments from the bottom of a tank. Usually a plate near ground level is removed from the side of the tank to make the door.

the tools or instruments, such as bailers and swabs, used to clean out an oilwell.

in electronic instrumentation, to restore a storage device, memory device, or binary stage to a prescribed state, usually that denoting zero. Also known as reset.

a drilling fluid made up mainly of chemical salts, such as sodium chloride, calcium chloride, or potassium chloride. Clear brine contains little or no clay or other solid material and is virtually transparent. It is often used when drilling into a producing formation because clear brine minimizes formation damage. See completion fluid, formation damage.

on a panel of rectangular floor or deck grating on an offshore installation, the distance between the supporting bars of the panel.

on offshore installations with grated decks or floors, the length of the load bearing bars (the supports) that go between two other supports.

to establish the full legal status of the land in question before executing a lease.

drilling operations in which plain water (usually salt water) is used as the circulating fluid.

1. the distance by which one object clears another. 2. the amount of space between two objects.

a device mounted on the cylinder of a compressor that allows the amount of clearance space to be adjusted. Clearance space may have to be adjusted to compensate for increases or decreases in the load on the compressor.

in tank sampling, a spot sample taken 4 inches (100 millimetres) below the level of the tank outlet.

in a reciprocating compressor, the volume between the top of the piston and the cylinder head with the piston at the top of its stroke.

the amount of space between the traveling and standing valves in a sucker rod pump when the pump is at the bottom of its stroke.

see coal cleat.

see shackle.

choke-line friction pressure.

the average weather or the regular variations in weather in an area over a period of years.

the amount of oil that adheres to the wall of a measuring or prover tank after draining.

finely shredded cellophane used as a lost circulation material for cement.

a U-bolt or similar device used to fasten parts of a wire cable together. v: in electronics, to prevent the amplitude of a waveform from exceeding a specified level while preserving the shape of the waveform at amplitudes less than the specified level.

an electronic circuit used to prevent the amplitude of a waveform from exceeding a specified level while preserving the shape of the waveform at amplitudes less than the specified level. Also called a limiter.

in electronics, the act of preventing the amplitude of a waveform from exceeding a specified level while preserving the shape of the waveform. Also called limiting.

see timing circuit.

1. to shut in a well temporarily that is capable of producing oil or gas. 2. to close the blowout preventers on a well to control a kick. The blowout preventers close off the annulus so that pressure from below cannot flow to the surface.

a very short piece of pipe threaded its entire length.

1. a life-support system in which the gas is recycled continually while the carbon dioxide is removed and oxygen added periodically. 2. a television installation in which the signal is transmitted by wire to a limited number of receivers.

in meteorology, a line drawn on a weather map connecting points of equal atmospheric pressure (an isobar) that forms a circular pattern on the chart and indicates an area of low pressure circulating about a center. Compare open isobar.

in process control, a system of components that utilizes feedback from its output for comparison with the desired set point; any difference results in automatic correction of the desired output. Closed loop systems are used to automatically control processes and equipment without human intervention. See set point.

a formation with abnormally high pressures that is not connected to formations with normal pressures.

see positive-volume prover.

a water-handling system (such as a saltwater-disposal system) in which air is not allowed to enter, thereby preventing corrosion or scale.

see shut-in pressure.

on a drilling rig, a configuration (a system) that uses feedback and a reference for what constitutes normal operations (a set point). Such a system detects deviations from the norm and makes corrections to maintain an optimum operation.

the measurement in a tank after a delivery or receipt. Compare opening gauge.

a machine that braids wires into strands and strands into rope in the manufacture of wire rope. Also called a stranding machine.

in a blowout preventer stack, the amount of pressure supplied by the blowout preventer control unit that is required to close a preventer. See operating pressure.

the mathematical relation (the ratio) between the pressure in the hole and the operating-piston pressure needed to close the rams of a blowout preventer. The closing ratio represents the difference in area between the part of the ram preventer’s operating piston that is affected by wellbore pressure, and the part of the piston that closing pressure acts on.

see blowout preventer control unit.

another term for an electric or hydraulic pump on an accumulator that serves to pump hydraulic fluid under high pressure to the blowout preventers so that the preventers may be closed or opened.

an electric or hydraulic pump on an accumulator that pumps hydraulic fluid under high pressure to the blowout preventers so that they may be closed or opened.

1. the vertical distance between the top of an anticline, or dome, and the bottom, an indication of the amount of producing formation that may be expected. 2. the process of closing down a site, such as plugging and abandoning a well or filling in a pit.

in meteorology, a mass of visible, suspended water droplets or ice crystals that are formed by condensation in the atmosphere.

a claim or encumbrance that, if upheld by a court, would impair the owner’s title to the property.

the temperature at which paraffin wax begins to congeal and become cloudy.

see cloud point.

special segmented weights attached to the guy wires of a guyed compliant platform that keep the guy wires taut as the platform jacket moves with the waves and current of the water. As tension on a guy wire is lessened, one or more segments of the weight drop to the seafloor and reestablish tension on the wire. As tension increases on a guy wire, the tension pulls one or more segments off the seafloor so that the wire is not overstressed.

a coupling used to connect and disconnect a driving and a driven part of a mechanism, especially a coupling that permits the former part to engage the latter gradually and without shock. In the oilfield, a clutch permits gradual engaging and disengaging of the equipment driven by a prime mover. v: to engage or disengage a clutch.

centimetre.

square centimetre.

cubic centimetre.