Glossary

1. hydrogen. 2. henry. 3. magnetizing force.

1. formation thickness; used in engineering reports during well testing. 2. hour.

circulating member with integral landing nipples.

hydrogen sulfide.

see trim.

sulfurous acid.

sulfuric acid.

a brand of hydraulic connector that allows the blowout preventer stack to be connected by remote control to the wellhead and to the lower marine riser package. The H4 connector has both a primary and secondary piston connected to a cam ring to provide locking and unlocking force. See hydraulic connector.

the clause in an oil and gas lease that fixes the duration of the lessee’s interest in both a primary and a secondary term. Also called term clause.

a thin spiraled recoil spring that regulates the motion of a pointer in a meter or a clock.

a logic element in an electronic circuit that operates on two binary digits, but no carry digits, from a preceding stage to produce as output a sum digit and a carry digit.

a cutoff pup joint below a packer that is used as a fluid entry device and a seal assemblies guide.

the flat, horizontal section of the bottom shell plating measured from the centerline of the vessel to the edge of the flat keel plate.

a single electrode immersed in an electrolyte for the purpose of measuring metal-to-electrolyte potentials and, therefore, the corrosion tendency of a particular system.

the amount of time needed for half of a quantity of radioactive substance to decay or transmute into a nonradioactive substance. Half-lives range from fractions of seconds to millions of years.

in chemistry, a molecule with a negative charge (a negative ion) that is made up of fluorine, chlorine, bromine, or iodine, and oxygen. Light sensitive silver halides, such as silver chloride and silver bromide, are used in conventional photographic processes. In the oilfield, halide ions in contact with steel downhole equipment cause localized pitting or crevice corrosion; halides also cause stress corrosion cracking.

rock salt (NaCl).

tool used to drive the conductor pipe into the ground. The single-acting diesel is the most popular, as it has the most foot-pounds of energy for the weight of the hammer. Other types of hammer include impact and vibrating.

a drilling tool that, when placed in the drill stem just above a roller cone bit, delivers high-frequency percussion blows to the rotating bit. Hammer drilling combines the basic features of rotary and cable-tool drilling (i.e., bit rotation and percussion).

a special flat-bottomed steel bit with carbide inserts used in straight hole drilling with air or gas. Normal tricone bits tend to split where the leg is welded to the body under the impact of the hammer. Several designs are available.

a method of locating corroded sections of pipe by striking the pipe with a hammer. When struck, a corroded section resounds differently from a noncorroded section.

see hammer drill.

connection of treating line during well servicing, from pump trucks to the tree or wellhead.

a worker in the oil industry, especially one in the field.

see marketing costs.

a coupling screwed onto casing tight enough so that a wrench must be used to remove it.

a railing or pipe along a passageway or stair that serves as a support or a guard.

a connection that can be unscrewed by hand.

to close a ram blowout preventer around the drill pipe when the annular preventer has previously been closed to offset the effect of heave on floating offshore rigs during well-control procedures.

to suspend sucker rods in a derrick or mast on rod hangers rather than to place them horizontally on a rack.

see hangline.

a device placed or hung in the casing below the blowout preventer stack to form a pressure-tight seal. Pressure is then applied to the blowout preventer stack in order to test it for leaks. Also called a hanger plug. See casing hanger, tubing hanger.

a device placed or hung in the casing below the blowout preventer stack to form a pressure-tight seal. Pressure is then applied to the blowout preventer stack to test it for leaks.

a device that fits around the top of a string of casing or a string of tubing and supports part of the weight of the casing or tubing while providing a pressure-tight seal. See hanger, packer.

the amount of weight transferred to the casinghead.

the rock surface forming the upper side of a fault when the fault plane is not vertical—that is, if the dip is less than 90°. Compare footwall.

a single length of wire rope attached to the crown block by which the traveling block is suspended when not in use. Also called a hang-off line.

hazardous airborne pollutant.

a special wear-resistant material often applied to tool joints to prevent abrasive wear to the area when the pipe is being rotated downhole.

either hand- or mechanically-made splice in either wire or synthetic rope with insertion of steel or synthetic material thimble.

a hard plastic helmet worn by oilfield workers to minimize the danger of being injured by falling objects.

in a well-control operation, closing the BOP without first opening an alternate flow path up the choke line. When the BOP is closed, pressure in the annulus cannot be read on the casing pressure gauge.

water that contains dissolved compounds of calcium, magnesium, or both. Compare soft water.

the capability of a metal alloy to be hardened by heat treatment.

in paint technology, a cross-linking agent used to cure a resin or a paint.

an extremely hard material, usually crushed tungsten carbide, that is applied to the outside surfaces of tool joints, drill collars, stabilizers, and other rotary drilling tools to minimize wear when they are in contact with the wall of the hole.

the resistance of a substance to scratching or to indentation.

one of several types of tests to determine a metal’s hardness. Many methods are available but the most common involves indenting the metal and measuring the indent’s depth or its size.

any quantity that produces a sheen, sludge, film, or discoloration of the surface water in navigable U.S. waters.

a periodic motion with a single frequency or amplitude or one that is composed of two or more such motions.

the combination of straps and fasteners used to attach equipment and umbilical to the diver which can be utilized as a lifting point to remove the diver from the water in the event of an emergency.

highway addressable remote transducer.

a form of digital communication produced by a transducer that uses frequency bursts and lapses to simulate the logic 1 or 0. The frequency can be superimposed on a DC bus or circuit by the transducer or transmitter for data transmission to a remote device for the purposes of programming or modification.

a definite arrangement of digital data produced by the HART transducer that is an established protocol recognized by the receiving unit.

1. an opening in the roof of a tank through which a gauging line may be lowered to measure its contents. 2. the opening from the deck into the cargo space of ships.

a rope, usually of large diameter, used to moor or tow marine vessels.

excelsior, used in emulsion treating to encourage coalescence.

a pulley that is normally attached to the wellhead at a convenient place for the wireline to pass through as it comes from the stuffing box sheave before being spooled onto the wireline reel. The hay pulley prevents any lateral force from being exerted on the lubricator and the wellhead.

a section of a heater or a heater-treater that is filled with fibrous material through which oil and water emulsions are filtered.

(obsolete) a rack used to hold pipe on a derrick; a fingerboard.

see hayrack.

an OSHA standard that guarantees employees the right to know about chemical hazards on the job and how to protect themselves from those hazards. Under HAZCOM, all manufacturers and employers must prepare a written hazard communication program; prepare a list of all hazardous materials in the workplace; label all containers of hazardous materials in the workplace; collect and maintain a material safety data sheet (MSDS) for each hazardous material present in the workplace; and provide employee training on specific topics related to hazardous substances.

(OSHA) any words, pictures, symbols, or combination thereof appearing on a label or other appropriate form of warning that convey the hazard(s) of the chemical(s) in the container(s).

involving or exposing one to risk. The lists of material or waste that are considered hazardous vary from agency to agency and from regulation to regulation: hazardous materials in transport are regulated by DOT; hazardous substances in the workplace are regulated by OSHA; hazardous waste is regulated under EPA’s RCRA; toxic substances are regulated under EPA’s TSCA; hazardous air pollutants are regulated under EPA’s CAA; and so on. The hazardous list for that regulation is tailored to that purpose.

(CAA) air emissions that are immediately hazardous to human health or that cause cancer, gene mutation, or reproductive harm. Due to its harmful nature, the allowable emission of a hazardous airborne pollutant is much lower than that for a conventional, or criteria, pollutant.

1. (OSHA) (HAZCOM) any chemical that is a physical hazard or a health hazard. 2. (SARA) any hazardous chemical as defined under 29 CFR 1910.1200(c), except those that are regulated by other agencies or laws.

(DOT) substances or materials in quantities or forms that may pose an unreasonable risk to health, safety, or property when stored, transported, or used in commerce.

a training level achieved by any employee who has been HAZWOPER trained to assist and support a hazardous materials technician in making certain emergency action decisions. The duties of hazardous materials specialists parallel those of the technician, but require a more directed or specific knowledge of the various substances they may be called on to contain. The hazardous materials specialist also acts as the site liaison with federal, state, local, and other government authorities in regard to site activities.

a training level achieved by any employee who has been HAZWOPER trained to take an offensive role in emergency response. Technicians are trained to take certain actions that deal directly with stopping a release, such as approaching the point of release to plug, patch, or otherwise stop the release.

1. any substance designated under CWA or CERCLA as posing a threat to waterways and the environment when released. 2. (CERCLA) any substance designated in 40 CFR 302.

1. any solid waste (“solid” includes any solid, liquid, semisolid, or contained gaseous material) resulting from industrial, commercial, mining, or agricultural operations, or from community activities, that meets certain characteristics of hazard (i.e., ignitable, corrosive, reactive, toxic) or that is listed as a waste from specific or nonspecific sources or that is a listed commercial chemical product or manufacturing intermediate that is sometimes discarded. 2. (RCRA) discarded materials regulated by the EPA because of public health and safety concerns. 3. (under HAZWOPER) a waste or combination of wastes as defined in 40 CFR 261.3, or those substances defined as hazardous wastes in 49 CFR 171.8.3. (CERCLA) those wastes listed in 40 CFR 261.3.

an operator that produces hazardous or acute hazardous waste. If the quantity of waste exceeds EPA minimums under RCRA, the operator must obtain a generator identification number and must meet other RCRA requirements. The hazardous waste generator must place hazardous wastes in proper containers; label the containers; ensure safe handling of the material; manifest shipments to licensed disposal sites; and report discrepancies in waste shipments to the EPA.

a document that identifies the waste and all parties responsible for it while it is being shipped.

an OSHA standard that is concerned primarily with worker safety in emergency response situations. HAZWOPER requires employers to protect the safety and health of three specific groups of workers: those involved in emergency response or cleanup at hazardous waste sites; those involved in emergency response at treatment, storage, and disposal (TSD) sites; and those involved in emergency response to incidents involving hazardous substances.

Hazard Communication Standard.

hazardous material.

the designated and trained personnel who respond to hazardous material incidents.

Hazardous Waste Operations and Emergency Response Standard.

held by production; commonly used in land departments.

a brand of hydraulic connector in subsea blowout preventer systems used to connect by remote control the blowout preventer stack to the wellhead and the lower marine riser package to the blowout preventer stack. It uses a large annular piston that completely surrounds locking segments, instead of the nine individual pistons. The additional locking force available through the annular piston increases the pressure rating to 15,000 psi (105,000 kPa) and improves the resistance to bending moments. See hydraulic connector.

hydrogen cyanide.

hydrogen cyanide.

trade name for a remote-controlled valve on the choke line that controls the flow of fluids through the line from the well to the choke manifold.

Hazard Communication Standard.

1. the height of a column of liquid required to produce a specific pressure. See hydraulic head. 2. for centrifugal pumps, the velocity of flowing fluid converted into pressure expressed in feet or metres of flowing fluid. Also called velocity head. 3. that part of a machine (such as a pump or an engine) that is on the end of the cylinder opposite the crankshaft. Also called cylinder head.

a thin piece of material made of cork or other similar material placed between an engine’s cylinder head and engine block. It seals between the head and block, and flexes to maintain the seal as the head and block expand at different rates with changes in engine temperature.

1. a constriction placed in a closed conduit of flowing fluid. 2. a flowmeter that depends on pressure head change to operate.

see head.

in crane operations, the vertical distance the crane can hoist a load before it strikes an obstruction.

crew chief.

(slang) the position in which the mast on a mobile rig is resting horizontally over the driver’s cab.

the post on cable-tool rigs that supports the end of the walking beam when the rig is not operating.

a chamber from which fluid is distributed to smaller pipes or conduits, e.g., a manifold.

the gate valve nearest the pump or compressor on oil or gas lines.

1. intermittent flow of fluid from a well. 2. direction in which a vessel is pointed.

in river craft of rectangular shape, the structural member at the extreme end between the rake shell plating and the deck.

(OSHA) the potential human health hazard associated with contact with materials or substances. A chemical that is listed as a health hazard is a chemical for which there is statistically significant evidence based on at least one study conducted in accordance with established scientific principles that acute or chronic health effects may occur in exposed employees.

a phrase covering a company’s concern for the health and safety of its employees, as well as the environment in which they work.

to loosen a collar or other threaded connection by striking it with a hammer. Also called warm a connection or whip a connection.

a condition that occurs when the cutters of a bit drag on a formation and become very hot because of friction and then are cooled by the drilling fluid; the rapid cooling causes small cracks (heat checks) to develop.

a process in which substances are transformed to a different state of matter.

see exchanger.

reboiler temperature.

a material, either flowing or static, used to transport heat from a primary source such as combustion of fuel to another material.

see heating medium.

see heating value.

heat generated when cement is mixed with water to form a slurry. Also called heat of reaction or heat of solution.

see heat of hydration.

see heat of hydration.

the quantity of energy required to evaporate 1 mole of a liquid at constant pressure and temperature.

pipes, 2 inches (5 centimetres) in diameter, which keep the soil stable in permafrost areas by cooling the ground.

an electric heater that is similar to an air conditioner. It heats and cools from a single system by reversing the flow of gas from the compressor to coils.

container or vessel enclosing an arrangement of tubes and a firebox in which an emulsion is heated before further treating, or in which natural gas is heated in the field to prevent the formation of hydrates.

a vessel that heats an emulsion and removes water and gas from the oil to raise it to a quality acceptable for a pipeline or other means of transport. A heater-treater is a combination of a heater, free-water knockout, and oil and gas separator.

flexible, insulated wire of known resistance, which can be wrapped around or strapped to a pipeline or valves for heating.

(marine) a system of piping in tank bottoms in which steam is carried as required to heat high pour-point liquid cargoes to pumpable viscosity level.

a material, whether flowing or static, used to transport heat from a primary source such as combustion of fuel to another material. Heating oil and steam are examples of heating mediums. Also called heat medium.

see fire tube.

the amount of heat developed by the complete combustion of a unit quantity of a material. Also called heat of combustion.

the vertical motion of a ship or a floating offshore drilling rig.

a device that moves with the heave of a floating offshore drill­ing rig to prevent the bit from being lifted off the bottom of the hole and then dropped back down (i.e., to maintain constant weight on the bit). It is used with devices such as bumper subs. See motion compensator.

the partial or complete collapse of the walls of a hole resulting from internal pressures due primarily to swelling from hydration or formation gas pressures. See caving.

1. the parts of a hydrocarbon mixture that have the highest boiling point and the highest viscosity (such as fuel oils and waxes). 2. hexanes and heptanes in a natural gas stream. Compare light ends.

see heavy ends.

any metal with a density of 5.0 or greater, such as lead, mercury, copper, and cadmium, especially one that is toxic to organisms.

oil composed mainly of heavy ends.

1. A type of oil as in heavy pitch oil such as creosote and green oil. 2. The strong movement of an offshore vessel, as in the rolling motion created by waves and weather.

liquid that is not vaporized in the reboiler.

drill pipe that is manufactured with walls that are thicker than those in standard drill pipe. Special extra-length tool joints are attached to the heavier-walled tube. Typically, 5-inch heavy wall drill pipe weighs 50 pounds per foot (75 kilograms per metre); 5-inch conventional drill pipe weighs 19.5 pounds per foot (29 kilograms per metre). Also attached to the tube is a center wear pad that protects the outside diameter of the pipe from abrasion. Heavy wall pipe is often used in the drill stem just above the drill collars, in the transition zone between the stiffer collars and the more limber drill string, and in place of some drill collars to apply weight on the drill bit in small-diameter and horizontal holes. Sometimes erroneously called heavyweight drill pipe. Compare heavyweight drill pipe.

a substance or material added to cement to make it dense enough for use in high-pressure zones. Sand, barite, and hematite are some of the substances used as heavyweight additives.

drill pipe that is like conventional drill pipe except that it is manufactured with a thicker wall, which increases its weight and tensile strength. For example, 5-inch IEU grade E75 standard-weight drill pipe weighs 19.5 pounds per foot (29 kilograms per metre), while 5-inch IEU grade E75 heavyweight drill pipe weighs 25.60 pounds per foot (38.4 kilograms per metre). Heavyweight drill pipe is placed in the top of the string to support a very long string of pipe. Heavyweight drill pipe may be used in the drill stem when high-tensile strength drill pipe is required but high-grade steel cannot be used because of the high-grade steel’s susceptibility to hydrogen embrittlement, which is a form of corrosion caused by hydrogen sulfide. Compare heavy-walled drill pipe.

an internationally used unit of measurement equal to 2.47 acres.

a financial insurance device for minimizing losses and protecting profits during the production, storage, processing, and marketing of commodities. A marketer sells a product on the futures market and locks in prices for later delivery. That contract may then continue to be exchanged on the futures market among other marketers with similar concerns and expectations.

the inclination of a ship or a floating offshore drilling rig to one side, caused by wind, waves, or shifting weights on board. Also called list.

see gauge cutters.

spiral-shaped.

distortion of a pipe, due to compression, in a spiral or helix pattern. Compare sinusoidal buckling.

spooling of wire rope onto a drum on which the grooves take the form of a helix—that is, like the threads on a pipe end. Also called helical spooling.

the designated place for helicopter landings and departures. Sometimes called a heliport.

a helium-oxygen mix.

a landing pad for helicopters.

an electronic device that lowers the voice of divers breathing helium as part of their breathing-gas mixture so that the surface crew may understand them. Also called unscrambler, speech unscramble.

a protective enclosure for a diver’s entire head. It is part of the life-support system and also contains a communications system.

a unit of inductance in which an induced voltage (electromotive force) of 1 volt occurs in a circuit when the current changes at the rate of 1 ampere per second.

a pricing point for natural gas futures contracts that are traded on the New York Mercantile Exchange (NYMEX). The hub is a point on a natural gas pipeline in Erath, Louisiana, which is owned by Sabine Pipe Line Company. This pipeline connects with nine interstate and four intrastate pipelines. Spot and future prices at the Henry hub establish the primary price of natural gas for the North American gas market.

see hydrogen sulfide.

a saturated hydrocarbon of the paraffin series; one of the heavy ends in a gaseous hydrocarbon mixture.

whatever can be inherited. Of the two kinds of hereditaments, corporeal and incorporeal, the first usually includes tangible things and the second, rights connected with land. Land itself would be a corporeal hereditament; the right to rent would be an incorporeal hereditament.

see bull gear.

a venturi tube used to measure fluid flow when a low permanent pressure drop is required for measurement.

a unit in the metric system used to measure frequency in cycles per second.

a method of squeeze cementing in which cement is pumped in and the pumps are stopped for a few minutes. Pumping is started and stopped until the desired pressure is obtained.

see kelly.

a number based on powers of 16 that uses the decimal digits 0 to 9 and six more digits represented by the letters A, B, C, D, E, and F. A hexadecimal number is usually written with the subscript 16 to indicate that it is a hexadecimal number. For example, 84D1F16 is a hexadecimal number.

a kelly with a six-sided (hexagonal) cross section. Compare square kelly. See also kelly.

C6H14, a liquid hydrocarbon of the paraffin series.

see radiofax.

high gas-oil ratio; used in drilling reports.

hydraulic horsepower.

a mechanism in some packers to set and release the tool with a minimum of rotation.

the ability of a paint to obliterate the color difference of a substrate; opacity.

the drive for the drawworks drum used when hoisting loads are light.

the function of an HIPPS is to protect the downstream equipment against overpressure by closing the source. This is done by closing one or more dedicated safety shutoff valves to prevent further pressurization of the pipe located downstream of these valves.

type of synthetic fiber used in rope construction.

see permeability.

a drilling fluid with a pH range above 10.5, i.e., a high-alkalinity mud.

see porosity.

the tide at its highest level or the time of day at which it occurs. Compare low tide. See tide.

a liquid that, at the measurement or proving temperature of the meter, has a vapor pressure that is equal to or higher than atmospheric pressure. Compare low vapor pressure liquid.

alternate term for high-strength steel. See high-strength steel.

a heavy-duty torque wrench used to apply the required torque to flange bolts in the makeup of riser pipe. Correct torque must be used to ensure the correct preload on a riser connection; otherwise, separation at the flanges could lead to failure. See riser pipe.

in electronics, involving the rapid cycling of alternating current, radio waves, or sound waves.

a system on the residue gas scrubber to alert the operator when lean oil is about to flood the absorber.

an area of high atmospheric pressure.

in drilling, any fitting that is used to join (connect) two pieces of equipment that will undergo high pressures. For example, a high-pressure connector is necessary to join one length of pipe to another when the pipes are carrying cement from a cement mixing device to a cement head on the rig floor.

a system that operates at a pressure higher than the standard service pressure delivered to the customer; thus, a pressure regulator is required on each service to control pressure delivered to the customer. Sometimes called medium pressure.

a group of symptoms including a lack of coordination, tremors of the extremities, disorientation, nausea, dizziness, and brief lapses of consciousness occurring at depths of 500 feet (152 metres) or deeper.

pipeline in which gas is often compressed up to or in excess of 100 times the normal atmospheric pressure.

the forcing of cement slurry into a well at the point to be sealed with a final pressure equal to or greater than the formation breakdown pressure. See squeeze cementing.

in drilling from floating drilling rigs, a subsea device that is installed on top of the casing to provide a foundation for the blowout preventer stack, to support and house subsequent casing strings, and to provide a seal and a locking arrangement between the surface casing and blowout preventer stack.

water that has little or no ionic content and is therefore a poor conductor of electricity.

having high salt content.

low carbon steel with very small amounts of molybdenum, niobium, titanium, or vanadium. Also called high alloy steel, high-strength alloy steel or high-strength, low-alloy steel.

in vacuum pressure measurement, pressures that exert from 1 micrometre to 1 millimetre of mercury.

a classification given to a group of commercial drilling-clay preparations having a yield of 35 to 50 barrels (5,565 to 7,950 litres) per ton and intermediate between bentonite and low-yield clays. Usually prepared by peptizing low-yield calcium montmorillonite clays or, in a few cases, by blending some bentonite with the peptized low-yield clay.

an electronic device that converts one form of energy into another—in this case, frequency bursts and lapses into direct current—so that the direct current can transmit the data to a remote receiver for interpretation, modification, or programming.

a connector used in joining chain and/or wire where side loading might be experienced.

a two-piece master bushing that has a jointed, swinging device (a hinge) on each half into which large pins fit to hold the bushing together. A two-piece insert bowl to hold the slips fits inside this type of master bushing. Compare solid master bushing, split master bushing. See also insert bowl, master bushing, slips.

a section of steel grating on an offshore installation that has hinges to allow personnel to raise and lower the section of grating.

high integrity pressure protection system.

high-liquid-level-alarm.

hydrophilic-lipophilic balance.

human machine interface.

high modulus polyethylene.

heavily oil-cut mud; used in drilling reports.

the distortion of the hull of an offshore drilling rig when the bow and the stern are lower than the middle, caused by wave action or unbalanced or heavy loads. Compare sagging.

1. an arrangement of pulleys and wire rope or chain used for lifting heavy objects; a winch or similar device. 2. the drawworks. v: to raise or lift.

the process of lifting.

the cable that supports drill pipe, swivel, hook, and traveling block on a rotary drilling rig.

drawworks, drilling line, and traveling and crown blocks. Auxiliary hoisting components include catheads, catshaft, and air hoist.

the large flanged spool in the drawworks on which the hoisting cable is wound. See drawworks.

the relatively small pneumatically operated engine on an air hoist, or tugger.

also called a lifting sub or a lifting nipple. See lifting nipple.

the system on the rig that performs all the lifting on the rig, primarily the lifting and lowering of drill pipe out of and into the hole. It is composed of drilling line, traveling block, crown block, and drawworks. See also hoisting components.

a mechanical arrangement that prevents the upward movement of certain pieces of equipment installed in a well. A sucker rod pump may use a mechanical hold-down for attachment to a seating nipple.

a hydraulic, toothed device in a packer that uses differential pressure across the packer to grip casing and prevent upward packer movement.

hydrostatic pressure developed by the weight of the drilling fluid exerted on the bottom of the hole that tends to prevent cuttings from moving up the annulus.

the minimum current required to maintain a switching device, such as a silicon-controlled rectifier, in a closed, or conducting, state after it is energized or triggered.

1. in drilling operations, the wellbore or borehole. See borehole, wellbore. 2. in electronics, the space left in atoms as free electrons flow from one atom to another. Like free electrons, holes also flow from atom to atom but in the opposite direction from electrons. In electronics, conventional current flow is shown as hole flow and not electron flow. Consequently, circuit diagrams for electronic devices show current flowing from the positive terminal to the negative terminal.

the angle at which a hole deviates from vertical.

the lifting and removing of cuttings made by a bit’s cutters by the drilling fluid coming out the bit.

see caving.

the amount a wellbore is deflected from vertical.

the shape and size of the wellbore.

a device used to enlarge the size of an existing borehole. It has teeth arranged on its outside circumference to cut the formation as it rotates.

in a p-type semiconductor, that which occurs when an impurity atom with only three valence electrons is placed in a semiconducting material with four valence electrons. The fourth electron is left without an electron to pair with, which results in a hole. The hole conducts current.

a gap or void in coating on a pipeline or in paint on a metal surface.

an electrical device used to locate a weak place, or holiday, in coatings on pipelines and equipment. Also called jeep.

a perforating gun consisting of a hollow, cylindrical metal tube into which are loaded shaped charges or bullets. On detonation, debris caused by the exploding charges falls into the carrier to be retrieved with the reusable gun.

property such as land, house, outbuildings, and tools, that cannot be seized to pay general debts.

a series of beds dipping in the same direction.

of uniform or similar nature throughout; a substance or fluid that has at all points the same property or composition.

rock whose characteristics (permeability, porosity, density, and so on) are generally similar throughout.

a stratum of rock that contains large void spaces, i.e., a cavernous or vuggy formation.

a large, hook-shaped device from which the swivel is suspended. It is designed to carry maximum loads ranging from 100 to 650 tons (90 to 590 tonnes) and turns on bearings in its supporting housing. A strong spring within the assembly cushions the weight of a stand (90 feet, about 27 metres) of drill pipe, thus permitting the pipe to be made up and broken out with less damage to the tool joint threads. Smaller hooks without the spring are used for handling tubing and sucker rods. See also stand, swivel.

block with a hook attached used in lifting service; may have a single sheave for double or triple line or multiple sheaves for four or more parts.

the weight of the drill stem that is suspended from the hook.

the nominal rated load capacity of a portable hoist and mast arrangement, usually calculated by an API formula.

a device in which a hook can be rotated to a required position and locked in place. Also called an automatic positioner.

on an offshore pedestal crane, one of a series of roller bearings on which the crane’s superstructure (including the operator’s cab) revolves. The rollers are installed in such a manner that they not only allow the crane superstructure to revolve, but also prevent the superstructure from separating from the pedestal when the crane performs lifts.

see combination hook-block.

a packer equipped with friction blocks or drag springs and slips and designed so that rotation of the pipe unlatches the slips. The friction springs prevent the slips from turning with the pipe and assist in advancing the slips up a tapered sleeve to engage the wall of the outside pipe as weight is put on the packer. Also called a wall-hook packer. See packer.

wire or cable used to connect components in an electronic device.

a force in the earth surrounding a borehole that stresses the hole somewhat like barrel hoops stress barrel staves. Hoop stress can cause the hole to collapse.

a large funnel- or cone-shaped device into which dry components (such as powdered clay or cement) can be poured to mix uniformly with water or other liquids. The liquid is injected through a nozzle at the bottom of the hopper. The resulting mixture may be drilling mud to be used as the circulating fluid in a rotary drilling operation, or it may be cement slurry to be used in bonding casing to the borehole.

distinct layer or group of layers of rock.

a the horizontal distance from the rotary table to the target. Compare vertical section. See departure.

deviation of the borehole at least 80° from vertical so that the borehole penetrates a productive formation in a manner parallel to the formation. A single horizontal hole can effectively drain a reservoir and eliminate the need for several vertical boreholes.

a heater-treater of cylindrical shape lying parallel to the ground. See heater-treater.

the permeability of reservoir rock parallel to the bedding plane. Compare vertical permeability.

a clause in an oil or gas lease that excludes, or releases, nonproducing acreage from the lease at the end of a specified period.

a separator of cylindrical shape lying parallel to the ground. See separator.

a diagram or plot that shows the planned trajectories between specified true vertical depths.

a preestablished location in the horizontal plane at ground level along the tank circumference. Compare vertical station.

a diagram or plot of well structures, both above and below the ground.

horizontal component of mooring line tension.

a directional well that is drilled about 90 degrees from vertical, so that the wellbore runs parallel to the surface. Horizontal wells have proven to be an effective way to exploit some reservoirs—for example, in limestone reservoirs with vertical fractures that contain hydrocarbons, a horizontal wellbore can penetrate several of the fractures to efficiently produce them.

the generally horsehead-shaped steel piece at the front of the beam of a pumping unit to which the bridle is attached in sucker rod pumping.

a unit of measure of work done by a machine. One horsepower equals 33,000 foot-pounds per minute. (Kilowatts are used to measure power in the international, or SI, system of measurement.)

a block of the earth’s crust that has been raised (relatively) between two faults. Compare graben.

in drilling from floating offshore drilling rigs that employ a subsea blowout preventer stack, a collection (a bundle) of several hoses enclosed in a heavy-duty protective cover. A hose bundle has several electrical and hydraulic control lines that run to the control pods on the subsea blowout preventers. When the driller or other person actuates a blowout preventer control on the rig at the surface, the control signal goes through the hose bundle to the control pod on the blowout preventer stack.

on offshore floating rigs, a large spool, or reel, onto which the hose bundle is wrapped. See hose bundle.

see hose bundle reel.

a process for removing the bulk of acid gases from a gas stream by contacting the stream with a water solution of potassium carbonate at a temperature in the range of 220°F to 240°F (104°C to 116°C).

see underwater burning.

1. absorption or other oil used as a heating medium. 2. oil produced in violation of state regulations or transported interstate in violation of federal regulations, or oil that is stolen.

the second pass made on a weld. The hot pass follows the root, or stringer, bead and precedes the filler pass and cap.

an abnormally hot place on a casing coupling when a joint is being made up. It usually indicates worn threads on the pipe and in the coupling.

to make repairs or modifications on a tank, pipeline, or other installation without shutting down operations.

see positive terminal.

a weld made on a pipeline already in service. The gas from the line is purposely ignited at the point where the welding is to be done, thereby eliminating the chance that a spark could cause an explosion of gas and air.

a method of thermal recovery in which water at the boiling point is injected into a formation to lower the viscosity of the oil and allow it to flow more freely toward producing wells. Although generally less effective than steam injection because of lower heat, hot waterflooding may be preferable under certain conditions, such as formation sensitivity to fresh water or high pressures.

a written document that affirms that a job involving tools that are sources of ignition or that are fire hazards (hot work) is necessary in a work area and, once signed by the persons doing the hot work and a supervisor, allows the work to occur. Usually, the permit requires that a person be standing by with a fire extinguisher while the work is in progress. Common hot work includes welding, soldering, and cutting and brazing. In some cases, a hot work permit is required when grinding if flammable materials are nearby.

see Schottky diode.

the treatment of a producing well with heated oil to melt accumulated paraffin in the tubing and the annulus.

a loose-fitting neoprene suit that disperses hot water pumped from the surface around the diver.

a wind-speed measuring device that has a thin platinum wire that electrical current heats to about 1,000 degrees Celsius (over 1,800 degrees Fahrenheit). A special instrument measures wind speed by examining either the wire’s change in resistance or the amount of current required to maintain the temperature of the wire when it is under the influence of wind.

something that covers or protects, as the casing for a moving mechanical part.

horsepower.

hydrostatic pressure.

high-pressure nervous syndrome.

hydraulic pressure unit.

hyperbaric rescue chamber.

trade name for a remote­-controlled valve on the choke line that controls the flow of fluids through the line from the well to the choke manifold.

health, safety, and environment.

a fitting for joining two pipes or devices; a metal disk (a hub) on each end of the pipes or devices to be connected are put together and bolted to form a pressure-tight seal.

(slang) cyclic steam injection.

the framework or body of a vessel including all decks, plating, and columns, but excluding machinery.

the apparatus that allows a human operator to work and interact with nonhuman equipment.

organic acids of indefinite composition in naturally occurring leonardite lignite. The humic acids are the most valuable constituent. See lignins.

a measure of moisture content in dry air; an expression of the amount of water dispersed as vapor in a quantity of dry air or other gas, usually expressed as grains of water per pound of dry air. See absolute humidity, relative humidity.

a surge of engine speed to a higher number of revolutions per minute (rpm), followed by a drop to normal speed without manual movement of the throttle. It is often caused by a faulty or improperly adjusted governor.

a tropical storm with high winds and heavy rains that occurs in the North Atlantic, the Caribbean, the Gulf of Mexico, and in the Eastern Pacific and Central Pacific. Pacific hurricanes, however, are called typhoons.

an announcement warning that hurricane-force winds are in the area and advising inhabitants in that area to seek shelter.

an announcement warning that hurricane-force winds may pose a threat to an area and cautioning inhabitants in that area to listen for subsequent advisories.

heavy-walled drill pipe or heavyweight drill pipe.

hydraulic workover unit.

having a pressure greater than that within the body tissues or fluids.

a drill bit having both roller cones and fixed blades used in drilling. The cutting elements on the fixed blades form a continuous cutting profile from the perimeter of the bit body to the axial center. The roller cone cutting elements crush and pre- or partially fracture a formation in the confined sections.

combine natural and synthetic diamonds and sometimes tungsten carbide inserts on a fixed-head bit.

the copyrighted name of a method of hydraulic fracturing for increasing productivity.

a hydrocarbon and water compound that is formed under reduced temperature and pressure in places where gas that contains water vapor occurs. For example, hydrates can form in gathering, compression, and transmission facilities for gas. They can also form in deepwater drilling where low temperatures occur on or near the seafloor and where gas containing water vapor may be encountered by the borehole. Hydrates can accumulate in troublesome amounts and impede fluid flow. They resemble snow or ice and decompose at atmospheric pressure. v: to enlarge by taking water on or in.

see plug.

in drilling from floating rigs that use a subsea blowout preventer stack and marine riser system, a groove in the lower body of a hydraulic connector that forms a seal with the outside of the wellhead.

calcium hydroxide, Ca(OH)2, a dry powder obtained by treating quicklime with enough water to satisfy its chemical affinity for water.

1. a chemical reaction in which molecular water is added to the molecule of another compound without breaking it down. 2. reaction of powdered cement with water. The cement gradually sets to a solid as hydration continues.

1. of or relating to water or other liquid in motion. 2. operated, moved, or effected by water or liquid.

a cylinder or fluid motor that converts hydraulic power into useful mechanical work; mechanical motion produced may be linear, rotary, or oscillatory.

the area available for flow at a restriction.

booster stations located along the trunkline assure that the work load for each station is approximately equal.

a bonding of cement to the casing or to the formation that blocks the migration of fluids. It is usually determined by applying increasing amounts of liquid pressure at the pipe-cement or formation-cement interface until leakage occurs.

in a ram preventer, the devices in the ram housing (the bonnet) that open or close the rams when activated with hydraulic pressure from the blowout preventer operating unit (accumulator).

also called hydrodynamic brake or Hydromatic® brake. See hydrodynamic brake.

in drilling from offshore floating rigs, a device that attaches (connects) the blowout preventer stack to the wellhead and to the lower marine riser package. It is controlled from the surface. Hydraulic connectors consist of a lower body, an upper body, a cam ring, locking dogs (or segments), a seal groove, and a hydraulic system. See lower marine riser package.

a device used on floating offshore drilling rigs to provide a way to actuate and control subsea blowout preventers from the rig on the surface. Hydraulic and electrical lines from the rig enter the pods, through which fluid and electrical signals are sent to the preventer. Usually two pods, one yellow and one blue, are used, each to safeguard and back up the other. Also called blue pod, yellow pod.

a fluid connection between a prime mover and the machine it drives; it uses the action of liquid moving against blades to drive the machine. Also called fluid coupling.

a liquid of low viscosity (such as light oil) that is used in systems actuated by liquid (such as the brake system in a modern passenger car).

force resulting from pressure on water or other hydraulic fluid.

an operation in which a specially blended liquid is pumped down a well and into a formation under pressure high enough to cause the formation to crack open, forming passages through which oil can flow into the wellbore. Sand grains, aluminum pellets, glass beads, or similar materials are carried in suspension into the fractures. When the pressure is released at the surface, the fractures partially close on the proppants, leaving channels for oil to flow through to the well. Compare explosive fracturing.

a governor on an engine that operates by means of oil inside its housing. Unlike a mechanical governor, which is mechanically linked to the engine’s speed control, a hydraulic governor operates the speed control with oil pressure inside the governor. See governor. Compare mechanical governor.

see fluid knock, water hammer.

the force exerted by a column of liquid expressed by the height of the liquid above the point at which the pressure is measured. Although “head” refers to distance or height, it is used to express pressure, since the force of the liquid column is directly proportional to its height. Also called head or hydrostatic head. Compare hydrostatic pressure.

equipment associated with a high-pressure rotating head that circulates hydraulic fluid to cool and lubricate the bearings on which the rotating head’s stripper rubber rotates. The hydraulic heat-exchanger system transfers heat generated by the load on the rotating head and cools the bearing pack.

an accessory or integral part of a packer used to limit the packer’s upward movement under pressure.

a measure of the power of a fluid under pressure.

a type of mechanical jar in which a fluid moving through a small opening slows the piston stroke while the crew stretches the work string. After the hydraulic delay, a release mechanism in the jar trips to allow a mandrel to spring up and deliver a sharp blow. Compare mechanical jar, rotary jar.

the use of sand pumped through horizontally positioned orifices installed in the tubing string to jet holes in the casing and cement sheath into the formation.

a specialized form of hydraulic pump, used in artificial lift, whose main working parts are nozzle, throat, and diffuser. The nozzle converts the high-pressure, low-velocity energy of the power fluid to high-velocity, low-pressure energy. The power fluid is then mixed with the low-pressure pump intake fluid in the throat to produce a low-pressure stream with a velocity less than that of the nozzle exit, but a high velocity, nevertheless. The velocity energy of this mixed stream is then converted to static pressure in the diffuser to provide the pressure necessary to lift fluid from the well. The power fluid may be either oil or water.

on a blowout preventer control unit (accumulator), a housing (box) with several inlet and outlet ports. The inlet ports receive the accumulator’s operating fluid; the outlets send the fluid to the yellow and blue control pods, which, in turn, operate the blowout preventers.

see hydraulic heat-exchanger module.

a device that may be driven by electricity or air that, when actuated, applies pressure to stored hydraulic fluid, which, in turn, drives another device.

see blowout preventer control unit.

1. a device that lifts oil from wells without the use of sucker rods. See hydraulic pumping. 2. a device that creates pressure on a fluid, usually special hydraulic fluid, to move the fluid.

a method of pumping oil from wells by using a downhole pump without sucker rods. Subsurface hydraulic pumps consist of two reciprocating pumps coupled and placed in the well. One pump functions as an engine and drives the other pump (the production pump). The downhole engine is usually operated by clean crude oil under pressure (power oil) that is drawn from a power-oil settling tank by a triplex plunger pump on the surface. If a single string of tubing is used, power oil is pumped down the tubing string to the pump, which is seated in the string, and a mixture of power oil and produced fluid is returned through the casing-tubing annulus. If two parallel strings are used, one supplies power oil to the pump while the other returns the exhaust and produced oil to the surface. A hydraulic pump may be used to pump several wells from a central source and has been used to lift oil from depths of more than 10,000 feet (3,048 metres).

a cylinder and piston device that uses hydraulic pressure for pushing, lifting, or pulling. It is commonly used to raise portable masts from a horizontal to a vertical position, for leveling a production rig at an uneven location, or for closing a blowout preventer against pressure.

on a drilling rig’s hook, a device inside the hook that is filled with hydraulic fluid. It dampens the tendency of the hook to bounce (move rapidly up and down) when crew members break out a joint of drill pipe. As the last engaged threads of the tool joint pin clears the box threads, the release may be sudden and, if not dampened, the pin could easily strike the box and damage the threads on both.

a self-contained machine powered by hydraulic fluid that puts pipe into the hole or takes it out of the hole when pressure in the hole is great enough to force the pipe out of the hole if the snubbing unit did not hold back the pipe. A hydraulic snubbing unit consists of control heads (special BOPs), stationary and traveling snubbers, operating manifold, rotary table, and the hydraulic system. Hydraulic jacks control the movement of the pipe out of or into the hole.

on an engine, a device used to start the engine that uses hydraulic fluid under pressure to operate a motor on the starter. When engaged, the starter motor turns the engine’s flywheel to make the engine start.

a sucker rod pumping unit that uses reciprocal hydraulic pumps. Few are still in operation.

piping that carries hydraulic operating fluid from a storage container to a device that is operated by hydraulic fluid—for example, the piping from an accumulator to a blowout preventer.

see hydraulic coupling.

a hydraulically powered device that can break out or make up tool joints and assure accurate torque. It is fitted with a repeater gauge so that the driller can monitor tool joints as they go downhole, doubly assuring that all have the correct torque.

a series of hydraulic rams to restrain and pull tubing under well pressure, temporarily attached to the wellhead for workover.

a series of hydraulic rams to restrain and pull tubing under well pressure, temporarily attached to the wellhead for workover.

a stand-alone snubbing unit.

a packer that is set using pressure applied either by pistons actuated by formation pressure or using externally applied pump pressure.

a device attached to the telescopic joint on a floating rig’s marine riser system that allows the telescopic joint to be run and retrieved without removing tensioner lines. The ring is hydraulically latched to the outer barrel as the joint is run, and hydraulically latched to the diverter housing as the joint is being retrieved.

1. the branch of science that deals with practical applications of water or other liquid in motion. 2. the planning and operation of a rig hydraulics program, coordinating the power of circulating fluid at the bit with other aspects of the drilling program so that bottomhole cleaning is maximized.

the registered trademark of a prominent manufacturer of oilfield equipment, including annular and ram blowout preventers and casing and tubing joints.

a method used to prevent liquid condensation in the pipeline grid under various pressures and temperatures. Includes refrigerated low-temperature separation (LTS), expander, Joule-Thomson (JT), and silica gel.

the volume of the pore space in a reservoir that is occupied by oil, natural gas, or other hydrocarbons (including nonhydrocarbon impurities). It may be expressed in acre-feet, barrels, or cubic feet.

a process for the removal of H2S, CO2, and other sulfur compounds called acid gases. See sweetening.

equipment used in the process of removing H2S, CO2, and other sulfur compounds called acid gases.

organic compounds of hydrogen and carbon whose densities, boiling points, and freezing points increase as their molecular weights increase. Although composed of only two elements, hydrocarbons exist in a variety of compounds because of the strong affinity of the carbon atom for other atoms and for itself. The smallest molecules of hydrocarbons are gaseous; the largest are solids. Petroleum is a mixture of many different hydrocarbons.

an acid compound, HCl, commonly used to acidize carbonate rocks. It is prepared by mixing hydrogen chloride gas in water. Also known as muriatic acid.

cracked naphtha for making gasoline.

cracking in the presence of low-pressure hydrogen, consuming a net amount of hydrogen in the process.

see hydrogen cyanide.

a cone-shaped separator for separating various sizes of particles and liquid by centrifugal force. See desander, desilter.

a device mounted on the end of the drawworks shaft of a drilling rig. It serves as an auxiliary to the mechanical brake when pipe is lowered into the well. The braking effect is achieved by means of an impeller turning in a housing filled with water. Sometimes called hydraulic brake or Hydromatic® brake.

a petroleum trap in which the major trapping mechanism is the force of moving water.

a special wash­pipe assembly used in swivels and top drives that uses externally mounted hydraulic cylinders and high-pressure hydraulic lines. The lines conduct hydraulic oil to the washpipe and puts external pressure on the washpipe packing. The external pressure forces the packing away from the washpipe so that a thin film of hydraulic oil exists between the packing and the washpipe. The packing therefore does not directly contact the washpipe and, consequently, wear is reduced. When drilling with mud pump pressures higher than 3,000 pounds per square inch (20,685 kilopascals), wear on conventional washpipe packing accelerates rapidly. Hydrodynamic washpipe can be used with pump pressures as high as 7,500 pounds per square inch or 51,713 kilopascals to markedly reduce washpipe packing wear.

driven by water power.

a method of reserving, or storing, energy in which the excess electrical energy that a hydroelectric generating facility (usually a dam) produces during times of low electricity demand is used to pump water into a large storage area. This stored water is then released at times of high demand to operate hydroelectric generators.

a strong, poisonous liquid acid compound of hydrogen and fluorine (HF). Often mixed with hydrochloric acid, it is used mainly to remove mud from the wellbore and surrounding formation pores. Also called mud acid.

a mixture of acids used for removal of mud from the wellbore. See mud acid.

a process of petroleum refining in which straight-run, cracked, or mixed naphthas are passed over a solid catalyst at elevated temperatures and moderate pressures in the presence of added hydrogen or hydrogen-containing gases. The main chemical reactions are dehydrogenation and aromatization of the nonaromatic constituents of the naphtha to form either high-octane motor fuel or high-grade aviation gasoline high in aromatic hydrocarbons such as toluene and xylenes. Ninety percent of the sulfur contained in the naphtha is removed.

another term for liquefied petroleum gas (LPG).

a flammable, colorless, odorless, tasteless gas whose chemical symbol is H and that usually occurs as the diatomic molecule H2. It is lighter than air; indeed, it is the lightest element in the universe.

an extremely poisonous compound of hydrogen, carbon, and nitrogen (HCN), with a boiling point of 79°F (26°C) and having the odor of bitter almonds. It is water-soluble in all proportions. Also called formonitrile, hydrocyanic acid, or prussic acid.

low ductility of a metal caused by its absorption of hydrogen gas. Also called acid brittleness.

a measure of the acidity or alkalinity of a solution, normally expressed as pH. See pH.

an instrument that, when attached to the exterior of a vessel that has been corroded by hydrogen sulfide, senses the hydrogen content in the steel and records the rate of corrosion.

a formation’s hydrogen content.

a flammable, colorless gaseous compound of hydrogen and sulfur (H2S), which in small amounts has the odor of rotten eggs. Sometimes found in petroleum, it causes the foul smell of petroleum fractions. In dangerous concentrations, it is extremely corrosive and poisonous, causing damage to skin, eyes, breathing passages, and lungs and attacking and paralyzing the nervous system, particularly that part controlling the lungs and heart. In large amounts, it deadens the sense of smell. Also called hepatic gas or sulfureted hydrogen.

see hydrogen sulfide cracking.

a type of corrosion that occurs when metals are exposed to hydrogen sulfide gas; it is characterized by minute cracks that form just under the metal’s surface.

to combine or treat with or expose to hydrogen.

the complete sequence of events repeated again and again (a cycle) through which water passes from the oceans, through the atmosphere, to the land, and back to the ocean.

the decomposition of a chemical compound by its reaction with water.

to undergo hydrolysis; a chemical process of decomposition involving splitting a bond and adding the elements of water.

trade name for a type of hydrodynamic brake.

an instrument with a graduated stem, used to determine the gravity of liquids. The liquid to be measured is placed in a cylinder, and the hydrometer dropped into it. It floats at a certain level in the liquid (high if the liquid is light, low if it is heavy), and the stem markings indicate the gravity of the liquid.

tending to adsorb water.

an expression of the relative attraction of an emulsifier for water and oil, determined largely by the chemical composition and ionization characteristics of a given emulsifier. The HLB of an emulsifier is not directly related to solubility, but it determines the type of emulsion that tends to be formed. It is an indication of the behavioral characteristics and not an indication of emulsifier efficiency.

tending to repel water.

a device trailed in an array behind a boat in offshore seismic exploration that is used to detect sound reflections, convert them to electric current, and send them through a cable to recording equipment on the boat.

a component of the riser tensioning system on a floating drilling rig that contains hydraulic fluid and high-pressure air and opposes heave placed on the system by ocean movements. See hydropneumatic riser-tensioning system.

the components (the system) that provide upward force (tension) on a marine riser’s tensioner lines. The system consists of hydropneumatic cylinders and sheave assemblies, accumulators and system air-pressure vessels, a control panel and piping manifold, high-pressure air compressors, and standby air-pressure vessels.

able to absorb water from the air.

a wireline pressure setting tool for setting permanent downhole tools.

a brand name of an air-motor starter. See air-motor starter.

relating to, involving, or typical of fluids that are at rest and the forces and pressures they exert.

a sand bailer that consists of a sealed cylinder with a rubber disk and a piercing tool at the bottom. A sharp blow on the bottom ruptures the disk, allowing the hydrostatic pressure of the well fluid to force sand into the bailer.

the pressure exerted by a body of water at rest. The hydrostatic head of fresh water is 0.433 psi per foot of height. Those other liquids may be determined by comparing their gravities with the gravity of water. See hydrostatic pressure, pressure gradient.

a hydraulically powered fishing tool that uses pressure differential to trap and retrieve junk from the bottom of the hole.

the force exerted by a body of fluid at rest. It increases directly with the density and the depth of the fluid and is expressed in many different units, including pounds per square inch or kilopascals. The hydrostatic pressure of fresh water is 0.433 pounds per square inch per foot (9.792 kilopascals per metre) of depth. In drilling, the term refers to the pressure exerted by the drilling fluid in the wellbore. In a water drive field, the term refers to the pressure that may furnish the primary energy for production. See hydrostatic head.

on an offshore rig, a list that includes the rig’s draft in feet or metres, its displacement, its water plane area in square feet or square metres, and its vertical center of buoyancy. Such tables provide the starting point for calculating the buoyancy, stability, and trim of an offshore floating rig.

the most common final quality-control check of the structural soundness of a pipeline. The line is filled with water and then pressured to a designated point. This pressure is maintained for a specified period of time, and any ruptures or leaks revealed by the test are repaired. The test is repeated until no problems are noted.

to apply hydraulic pressure to check for leaks in tubing or tubing couplings, usually as the tubing is being run into the well. If water leaks from any place in the tubing, the joint of tubing, the coupling, or both are replaced.

a method of removing sulfur, nitrogen, and metals from crude oil fractions.

a sub with a ball seat run on top of a hydraulically set packer to provide a means to set the packer.

a designation that is given for basic compounds containing the hydroxide (OH) radical. When these substances are dissolved in water, they increase the pH of the solution. See base.

an instrument used to measure water vapor in the air. See psychrometer, sling psychrometer.

absorbing or attracting moisture from the air.

relating to or utilizing greater than normal pressure.

a compartment designed to evacuate divers from the saturation complex in the event of a catastrophe that renders the complex uninhabitable.

excessive amount of carbon dioxide in the blood, often resulting from an excessive carbon dioxide partial pressure in a diver’s breathing supply. Also called carbon dioxide excess.

in a right triangle, the side opposite the right angle. See right triangle.

reduced body temperature caused by overexposure to chilling temperatures.

see anoxia.

1. the difference between the indications of a measuring instrument when the same value of the quantity measured is reached by increasing or decreasing the quantity. 2. the lagging of changes in the magnetization of a substance behind changes in the magnetic field as the magnetic field is varied.

in a transformer, the conversion of electrical energy to heat in the core of the transformer’s winding because of hysteresis (the lagging of changes in the core’s magnetic field as the transformer’s magnetic field is varied). See hysteresis.

hertz.