Oil & Gas Glossary 1.0

A well-servicing outfit used in pulling rods and tubing from the well. See production rig.

See production rig. Also see pulling unit.

A hoisting or pulling line operated from a cathead.

A machine used for pulling or hoisting that does so by winding a cable around a spool.

A spool-shaped attachment on a winch around which rope is wound for hoisting and pulling.

Heavy lifting mechanism used on rigs to provide a mechanical pulling and running advantage.

A portable servicing or workover rig that is self-propelled, using the hoisting engines for motive power. Because the driver's cab is mounted on the end opposite the mast support, the unit must be backed up to the wellhead. See carrier rig.

A surface unit similar to a pumping unit but having no individual power plant. Usually, several pump jacks are operated by pull rods or cables from one central power source. Commonly, but erroneously, beam pumping units are called pump jacks. Compare beam pumping unit.

2. to stand pipe on the derrick floor when pulling it out of the hole.

Commonly referred to as snubbing; running of tool and/or pulling of tubing under well pressure.

2. in reference to an anchor, to fail to hold on a soft bottom, pulling out, instead, with a large ball of mud attached.

A type of portable service or workover rig that is self-propelled, using power from the hoisting engines. The driver's cab and steering wheel are mounted on the same end as the mast support; thus the unit can be driven straight ahead to reach the wellhead. See carrier rig.

The act of pulling tubing out of and running it back into a well.

To perform one or more of a variety of remedial operations on a producing oil well to try to increase production. Examples of workover opera6tions are deepening, plugging back, pulling and resetting liners, squeeze cementing, and so on.

The change in volume per unit of volume of a liquid caused by a unit change in pressure at constant temperature

The amount of heat required to cause a unit increase in temperature in a unit mass of a substance, expressed as numerically equal to the number of calories needed to raise the temperature of 1 gram of a substance by 1 degree C.

A portable derrick that is capable of being erected as a unit, as distinguished from a standard derrick that cannot be raised to a working position as a unit. For transporting by land, the mast can be divided into two or more sections to avoid excessive length extending from truck beds on the highway. Compare derrick.

A hydraulically operated tool that is run in above the fishing tool and anchored to the casing by slips. It exerts a strong upward pull on the fish by hydraulic power derived from fluid that is pumped down the fishing string.

A device that stores hydraulic fluid under pressure in special containers and provides a method to open and close the blowout preventers quickly and reliably. Usually, compressed air and hydraulic pressure provide the opening and closing force in the unit. See blowout preventer.

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.

A type of mobile offshore drilling unit that floats and is not secured to the seafloor (except for anchors). Floating units include inland barge rigs, drill ships and ship-shaped barges, and semisubmersibles. See mobile offshore drilling unit.

Unit chemical weight of solute per million unit weights of solution. The epm of a solute in solution is equal to the ppm (parts per million) divided by the equivalent weight.

A large, specially designed, self-propelled workover rig that a person drives 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. See back-in unit, drive-in unit.

A machine designed specifically for sucker rod pumping. An engine or motor (prime mover) is mounted on the unit to power a rotating crank. The crank moves a horizontal member (walking beam) up and down to produce reciprocating motion. This reciprocating motion operates the pump. Compare pump jack

A workover performed with a continuous steel tube, normally 3/4 inch to 1 inch outside diameter, which is run into the well in one piece inside the normal tubing. Lengths of the tubing up to 16,000 feet are stored on the surface on a reel in a manner similar to that used for wireline. The unit is rigged up over the wellhead. The tubing is injected through a control head that seals off the tubing and makes a pressure-tight connection. A unique feature of the unit is that it allows continuous circulation while it is being lowered into the hole.

A type of mobile offshore drilling unit that has a part of its structure in contact with the seafloor when it is on site and drilling a well. The remainder of the rig is supported above the water. The rig can float, however, allowing it to be moved from one drill site to another. Bottom-supported units include submersible rigs and jackup rigs. See mobile offshore drilling unit.

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

A well using a pumping unit and rods to lift fluid.

Abbreviation: mobile offshore drilling unit.

A floating offshore drilling unit that has pontoons and columns that when flooded cause the unit to submerge in the water to a predetermined depth. Living quarters, storage space, and so forth a reassembled on the deck. Semisubmersible rigs are either self-propelled or towed to a drilling site and either anchored or dynamically positioned over the site, or both. In shallow water, some semisubmersibles can be ballasted to rest on the seabed. Semisubmersibles are more stable than drill ships and ship-shaped barges and are used extensively to drill wildcat wells in rough waters such as the North Sea. Two types of semisubmersible rigs are the bottle-type semisubmersible and the column-stabilized semisubmersible. See floating offshore drilling rig.

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

A well-servicing unit whose mast consists of but one steel tube, usually about 65 feet long.

Two or more atoms behaving as a single chemical unit, i.e., as an atom, e.g., sulfate, phosphate, nitrate.

A stand of pipe made up or three joints and handled as a unit. Compare double, fourable, and single.

A mixture of barium sulfate, chemicals, and water of a unit density between 18 and 22 pounds per gallon

The oil company in charge of development and production in an oilfield in which several companies have joined to produce the field.

The assembly of pumps, valves, lines, accumulators, and other items necessary to open and close the blowout preventer equipment.

A bearing between the walking beam and the sampson post of a pumping unit.

One-millionth of a meter, a metric unit of measure of length equal to 0.001 meter.

A single unit which acts as an oil and gas separator, an oil heater, and an oil and water treater.

A unit of length equal to one millionth part of a meter, or one thousandth part of a millimeter.

3. the device in a fuel-injection unit that regulates the amount of fuel pumped on each stroke.

A mast mounted on a truck and capable of being erected as a single unit. See telescoping derrick.

The unit weight of fluid, e.g., pounds per gallon.

To have too long a length of rods between the pumping unit and the pump seat so that the pump hits bottom on the down stroke.

Well-control fluid that has been reduced in density or unit weight as a result of entrainment of less-dense formation fluids or air

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

Same as seal nipple assemblies.

Weight per unit volume of drilling fluid usually expressed in pounds per gallon or pounds per cubic foot. See hydrostatic pressure.

A lease or a number of leases of adjoining tracts of land that constitute a unit of acreage sufficient to justify the expense of drilling a wildcat.

The placement of compressors, pumps, cooling systems, treating systems, and so forth, in a series with another unit or units of like design to improve operating efficiency and results.

The walking beam of a pumping unit.

To install a pump or pumping unit, sucker rods, and bottom-hole pump.

A slot in the edge of the barge hull of a jackup drilling unit over which the drilling rig is mounted and through which drilling tools are lowered and removed from the well being drilled.

A minute unit of matter, usually a single crystal, or of regular shape with a specific gravity approximately that of a single crystal

A bed or deposit composed throughout of substantially the same kind of rock; often a lithologic unit. Each formation is given a name, frequently as a result of the study of the formation outcrop at the surface and sometimes based on fossils found in the formation.

An offshore drilling rig, usually with a large hull. It has a mat or legs that are lowered to the sea-floor and a main deck that is raised above the surface of the water to a distance where it will not be affected by the waves. Also called a jackup drilling rig.

The assembly of pumps, valves, lines, accumulators, and other items necessary to open and close the blowout preventer equipment. Also called closing unit.

1. to assemble and join parts to form a complete unit (e.g., to make up a string of casing). 2. to screw together two threaded pieces. 3. to mix or prepare (e.g., to make up a tank of mud). 4. to compensate for (e.g., to make up for lost time).

A laboratory unit used in pilot testing. One gram or pound equivalent, when added to 350 ml of fluid, is equivalent to 1 lb/bbl.

A preventer having a unit of packing material whose closure depends on well pressure coming from below. It is used primarily to strip pipe through the hole or allow pipe to be moved with pressure on the annulus.

A worker on an offshore rig who handles the equipment and supplies that are sent to the rig form the shore base. The head roustabout is very often the crane operator. a worker who assists the foreman in the general work around a producing oilwell, usually on the property of the oil company. A helper on a well servicing unit.

A mast on a well servicing unit that utilizes a split traveling block and crown block, which makes it possible to pull 60-foot stands with a 50-foot mast.

A sucker rod string, that is, the entire length of sucker rods, which usually consist of several single rods screwed together. The rod string serves as a mechanical link from the beam pumping unit on the surface to the sucker rod pump near the bottom of the well.

A unit of viscosity as measured with a Marsh funnel according to API procedure. See API RP 13B, Marsh funnel viscosity.

A fluid moving as a unit in which all shear stress occurs at the pipe wall and hole wall. The stream thus assumes the shape of several telescopic layers of fluid with lowest velocities near the pipe and hole walls and the fastest in the middle.

A portable servicing or workover outfit, usually mounted on wheels and self-propelled. A well servicing unit consists of a hoist and engine mounted on a wheeled chassis with a self-erecting mast. A workover rig is basically the same, with the addition of a substructure with rotary, pump, pits, and auxiliaries to permit handling and working a drill string.

The mass or weight of a substance per unit volume. For instance, the density of a drilling mud may be 10 pounds per gallon (ppg), 74.8 pounds per cubic foot (lb/ft), or 1,198.2 kilograms per cubic meter (kg/m3). Specific gravity, relative density, and API gravity are other units of density.

The force that a fluid (liquid or gas) exerts uniformly in all directions within a vessel, pipe, hole in the ground, and so forth, such as that exerted against the inner wall of a tank or that exerted on the bottom of the wellbore by a fluid. Pressure is expressed in terms of force exerted per unit of area, as pounds per square inch, or in kilopascals.

A laboratory unit used for evaluating or testing drilling fluids. One gram of material, when added to 350 milliliters of fluid, is equivalent to 1 pound of material when added to one 42-gal barrel of fluid.

A portable mast that an be erected as a unit, usually by a tackle that hoists the wireline or by hydraulic pistons. The upper section of a telescoping derrick is generally nested (telescoped) inside the lower section of the structure and raised to full height either by the wireline or by a hydraulic system.

The downhole assembly used to lift fluid to the surface by the reciprocating action of the sucker rod string. Basic components are barrel, plunger, valves, and hold-down. Two types of sucker rod pumps are the tubing pump, in which the barrel is attached to the tubing, and the rod, or insert, pump, which is run into the well as a complete unit.

A self-propelled floating offshore drilling unit that is a ship constructed to permit a well to e drilled from it. Although not as stable as semisubmersible, drill ships are capable of drilling exploratory wells in deep, remote waters. See floating offshore drilling rig.

N: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 centimeter long and 1 square centimeter in cross section will force a liquid of 1 centipoise of viscosity through the sample at the rate of 1 cubic centimeter per second. The permeability of reservoir rocks is usually so low that it is measured in millidarcys.

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

A special steel pumping rod. Several rods screwed together make up the mechanical link from the beam pumping unit on the surface to the sucker rod pump at the bottom of a well. Sucker rods are threaded on each end and manufactured to dimension standards and metal specifications set by the petroleum industry. Lengths are 25 or 30 feet (7.6 or 9.1 meters); diameter varies from 1/2 to 1-1/8 inches (12 to 30 millimeters). There is also a continuous sucker rod (tradename: Corod).

A unit of measure of the acid of alkaline condition of a substance. A neutral solution (such as pure water) has a pH of 7; add solutions are less than 7; basic, or alkaline, solutions are more than 7. The pH scale is a logarithmic scale. A substance with a pH of 4 is more than twice as add as a substance with a pH of 5. Similarly, a substance with a pH of 9 is more than twice as alkaline as a substance with a pH of 8.

Usually a single well drilled offshore by a mobile offshore drilling unit to produce hydrocarbons from the outer fringes of a reservoir that cannot be produced by primary development wells drilled from a permanent drilling structure (as a platform rig). Sometimes, several satellite wells will be drilled to exploit marginal reservoirs and avoid the enormous expense of erecting a platform.

A self-propelled floating offshore drilling unit that is a ship constructed to permit a well to be drilled from it. While not as stable as Semisubmersible, drill ships are capable of drilling exploratory wells in deep, remote waters. They may have a ship hull, a catamaran hull, or a trimaran hull. See floating offshore drilling rig.

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 meters) so that rods can be suspended as 50-foot (15 meter) doubles and tubing set back as 30-foot (9-meter) singles. See pole mast.

A drilling rig that is used exclusively to drill offshore exploration and development wells and that floats upon the surface of the water when being moved from one drill site to another. It may or may not float once drilling begins. Two basic types of mobile offshore drilling units are used to drill most offshore wildcat wells: bottom-supported drilling rigs and floating drilling rigs.

Drilling for oil or gas in an ocean, gulf, or sea, usually on the Outer Continental Shelf. A drilling unit for offshore operations may be a mobile floating vessel with a ship or barge hull, a semisubmersible or submersible base, a self-propelled or towed structure with jacking legs (jackup drilling rig), or a permanent structure used as a production platform when drilling is completed. In general, wildcat wells are drilled from mobile floating vessels or from jackups, while development wells are drilled from platforms or jackups.

The fundamental unit of mass of a substance. A mole of any substance is the number of grams or pounds indicated by its molecular weight. For example, water has a molecular weight of approximately 18. Therefore, a gram-mole of water is 18 grams of water; a poundmole or water is 18 pounds of water. See molecular weight.

The ability of a rock to transmit fluid through the pore spaces. - A key influence on the rate of flow, movement and drainage of the fluids. There is no necessary relation between porosity and permeability. A rock may be highly porous and yet impermeable if there is no communication between pores. A highly porous sand is usually highly permeable. A measure of the ease with which a fluid flows through the connecting pore spaces of rock or cement. The unit of measurement is the millidarcy. Fluid conductivity of a porous medium. Ability of a fluid to flow within the interconnected pore network of a porous medium.