Glossary

metre.

metacenter; this abbreviation is used mostly in buoyancy, stability, and trim calculations for offshore drilling rigs.

Maximum Allowable Working Pressure.

the methyl orange alkalinity of the filtrate, reported as the number of millimetres of 0.02 normal (N/50) acid required per millimetre of filtrate to reach the methyl orange end point (pH 4.3). M1 is a measure of the alkalinity of a drilling fluid. Usually, drilling fluids should have a high pH value (alkalinity) to ensure that they perform as they should.

square metre.

cubic metre.

milliampere.

mobile arctic caisson.

a workover rig, usually lightweight, that is specially built to run a string of I-inch or 1-inch (1.9- or 2.54-centimetre) tubing. See macaroni string.

a string of tubing or pipe, usually 3/4  or 1 inch (1.9 or 2.54 centimetres) in diameter.

a banded arrangement of cirrocumulus clouds.

the study of the overall characteristics and workings of a national economy; elements in the study include income, output, and the interrelationship among diverse economic sectors.

maximum achievable control technology.

see make up.

the hot fluid matter within the earth’s crust that is capable of intrusion or extrusion and that produces igneous rock when cooled.

trade name for the equipment and processes used for detecting cracks and other surface discontinuities in iron or steel. A magnetic field is set up in the part to be inspected, and a powder or paste of magnetic particles is applied. The particles arrange themselves around discontinuities in the metal, revealing defects.

a metal that has the property of attracting ferrous (iron) and certain other metals to it.

wire used as windings in electromagnets, transformers, motors, and generators. Its insulation must be thin so that it can be wound several times around a core. Thick insulation would not allow it to be wound an adequate number of times. So, instead of a plastic coating, varying grades of enamel or varnish are baked onto magnet wires to provide good insulating properties.

the principle that the opposite (north and south) poles of a magnet attract each other.

see electrodynamic brake.

the path magnetic lines of force (flux lines) take in an electrical device that employs magnets in its operation. A magnetic circuit is analogous to direct current flowing in a conductor such as wire or cable.

see declination.

the space that magnetic lines of force produced by a magnetic or current-carrying conductor.

a source of electricity that converts mechanical energy into electrical energy by the action of a magnetic field on a conductor when one is moving in relation to the other.

a device that senses and indicates the amount of fluid flowing in a line. It operates on the principle that a magnetic field induces voltage in an electrical conductor moving through the magnetic field. The conductor is the fluid flowing in the line. Field coils mounted on the sides of a special section of line create the magnetic field.

see flux.

see magnetite.

see magnetic lines of force.

the magnetism that emanates from a magnet’s north pole and travels in the atmosphere around the magnet to its south pole.

a meter used to measure the electrical conductivity of liquids.

any one of many methods of microscopic observation and study of magnetic material or forces.

a device used to determine the direction and drift angle of a deviated wellbore. It uses a magnetic compass to measure magnetic direction, which differs from true direction by the amount of local declination. See declination.

a region located in the north polar region of the earth toward which magnetic compasses point. Its location is different from true, or geographic, north. Compare true north.

a method that can be used to find surface and near surface flaws in ferromagnetic materials such as steel and iron. The technique uses the principle that magnetic lines of force (flux) will be distorted by the presence of a flaw in a manner that will reveal its presence. The flow, i.e., a crack, is located from the “flux leakage,” following the application of fine iron particles, to the area under examination. There are variations in the way the magnetic field is applied, but they are all dependent on the above principle. The iron particles can be applied dry or wet, suspended in a colored or fluorescent liquid. While magnetic particle inspection is primarily used to find surface breaking flaws, it can also be used to locate subsurface flaws. But its effectiveness quickly diminishes depending on the flaw depth and type.

a type of nondestructive testing for detecting surface and subsurface discontinuities in ferrous materials.

1. either of two regions that are located in the polar areas of the northern and southern hemispheres and toward which a compass needle points from any direction throughout adjacent regions. Compare geographic pole. 2. either of the poles of a magnet.

a survey picture in which the map’s compass points to magnetic north, a region located in the north polar region of the earth toward which magnetic compasses point. Its location is different from true, or geographic, north. Compare true readings.

the phenomenon that like poles (north-north or south-south) of a magnet repel, or repulse, each other.

an exploration method in which an instrument that measures the intensity of the natural magnetic forces existing in the earth’s subsurface is passed over the surface or through the water. The instrumentation detects deviations in magnetic forces, and such deviations may indicate the existence of underground formations that favor the entrapment of hydro­­carbons.

a device that measures and records the amount a borehole has deviated from vertical and, sometimes, the direction of the deviation. Such tools use magnetic compasses and therefore must be run inside a nonmagnetic drill collar to eliminate any magnetic interference from the drill string.

a device used to determine the direction and drift angle of a deviated wellbore. It uses a magnetic compass to measure magnetic direction, which differs from true direction by the amount of local declination.

a method of testing for defects in steel parts that is carried out by magnetizing the steel and sprinkling a magnetic powder on the surface to detect flaws or cracks. See magnetic particle inspection.

physical phenomena that include a magnet’s or lodestone’s attraction for iron and the forces associated with moving electricity; magnets and electric current exhibit these phenomena, which are characterized by fields of force.

the mineral form of black iron oxide, Fe3O4, that often occurs with magnesium, zinc, and manganese and is an important ore of iron. Also called lodestone, magnetic iron ore.

the part of exciting current that is 90 degrees out of phase with the impressed voltage on the circuit of a transformer and that produces magnetic flux in the transformer’s winding. See exciting current.

in an electric coil, or solenoid, the ampere-turns per inch of the length of the coil’s core to be magnetized. Just as a voltage drop, or loss of voltage, occurs along the length of a conductor that is carrying current, a magnetomotive drop occurs along the length of the magnetic circuit. The longer the magnetic circuit, the greater is the magnetomotive force required to magnetize the core to the desired amount.

a device (an alternator) that produces alternating current for distribution to the ignition system of some internal-combustion engines. See alternator.

an instrument used to measure the intensity and direction of a magnetic field, especially that of the earth.

in a magnetic circuit, the force that creates magnetic lines of force (magnetic flux); it is analogous to electromotive force, or voltage, in an electric circuit.

a tightly banded scroll of special steel that vibrates when a magnetic field is applied to it. The vibration of the scroll sets off a transmitter, which is alternately switched on and off at 15 to 60 times per second. The transmitter causes compressional sound waves to travel through the formations surrounding the borehole. Each formation material will exhibit its own characteristic effect on the elastic wave propagation.

a natural-source electromagnetic geophysical method of imaging the earth’s surface.

in an engine, a large circular friction-reducing device installed on the engine’s crankshaft. Main bearings are mounted in the engine’s crankcase and the crankshaft rotates on them. Engine oil lubricates them as the engine runs. Most main bearings are plain bearings, in that their wear surface is flat or plain and do not have balls or rollers. Compare ball bearing, roller bearing.

two bands fitted with brake pads; the bands fit over the two rims of the drawworks drum. When the driller engages this brake, the pads press down on the rims to stop the drum from hoisting or from letting out drilling line. The main brake also keeps the drum from rotating (and therefore holds the drill stem stationary) when making up or breaking out drill pipe.

the principal continuous deck of a ship or offshore drilling rig running from fore to aft from which the freeboard is determined.

in a drilling rig’s fuel-supply system, a large tank in which diesel fuel is stored. If the rig has a day tank, it is filled from the main tank; otherwise, the main tank supplies fuel to the engine. Compare day tank.

a large-diameter pipeline between distant points, i.e., a trunk line.

a plant that processes the gas that is being transported through a cross-country transmission line. Also called on-line, pipeline, or straddle plant.

a device for controlling fluid flow in a mainline.

a large oil company, such as ExxonMobil, Chevron, or BP Amoco, that not only produces oil, but also transports, refines, and markets it and its products.

the type of carrier, either electron or hole, that makes up more than half the carriers in a semiconductor.

to attach a joint of drill pipe onto the drill stem suspended in the wellbore to permit deepening the well­bore by the length of the joint (usually about 30 feet, or 9 metres).

(slang) to become a good worker.

to hoist the drill stem out of the wellbore to perform one of a number of operations, such as changing bits or taking a core, and so forth, and then to return the drill stem to the wellbore.

to deepen the hole made by the bit, i.e., to drill ahead; to run casing or pipe.

to create a fluid with the consistency of mud that occurs when clear water is circulated in a soft formation.

1. to assemble and join parts to form a complete unit (e.g., to make up a string of drill pipe). 2. to screw together two threaded pieces. Compare break out. 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).

to screw a length of pipe into another length of pipe.

a process that divers begin after assessment is complete. The process involves removing parts of the structure from the shallowest portion downward to gain access to the wells and pipelines. Divers can use many different methods to remove sections of the platform during the make-safe phase.

when connecting two threaded joints of pipe, the amount of turning force (torque) required to join the pipe to the correct tightness. It is important not to under torque or over torque (make up a joint too loosely or too tightly).

added to a system (e.g., makeup water used in mixing mud).

a device that is attached to the shaft of the drawworks and used as a power source for screwing together joints of pipe. It is usually located on the driller’s side of the drawworks. Also called spinning cathead. See cathead.

1. gas that is taken in succeeding years and has been paid for previously under a take-or-pay clause in a gas purchase contract. The contract will normally specify the number of years after payment in which the purchaser can take delivery of makeup gas without paying a second time. 2. gas injected into a reservoir to maintain a constant reservoir pressure and thereby prevent retrograde condensation. 3. in gas processing, the gas that makes up for plant losses. During processing there is a reduction in gas volume because of fuel and shrinkage. Some agreements between gas transmission companies and plant owners require plant losses to be made up or to be paid for.

tongs used for screwing one length of pipe into another for making up a joint. Compare breakout tongs. See also tongs.

the water used as a base in water-based drilling muds. It may be fresh, brackish, or salty.

see make hole.

see make up.

a pipe, coupling, or tool that has threads on the outside so that it can be joined to a female connection. Compare female connection.

breast-shaped protuberances appearing on the undersides of clouds, indicating the approach of a storm.

see human-machine interface.

a type of underbalanced drilling that precisely controls the annular pressure that occurs when drilling underbalanced. In MPD, the amount of annular pressure that is maintained on the wellbore is directly related to the formations through which the borehole passes. See underbalanced drilling (UBD).

a method of management that assumes that an organization is made up of independent and interacting parts. Systems theory postulates that all things exist as part of a larger complex of things. An impact on one element has an impact on all elements, although the impact may be small on some of the parts. Therefore, all things are interdependent and linked to one another.

a cylindrical bar, spindle, or shaft around which other parts are arranged or attached or that fits inside a cylinder or tube.

a hole in the top or side of a tank through which a person can enter.

1. an accessory system of piping to a main piping system (or another conduit) that serves to divide a flow into several parts, to combine several flows into one, or to reroute a flow to any one of several possible destinations. See choke manifold. 2. a pipe fitting with several side outlets to connect it with other pipes. 3. a fitting on an internal-combustion engine made to receive exhaust gases from several cylinders.

the number of cones needed in a mud cleaner to process the full volume of circulating mud.

a device installed on an engine’s intake manifold that indicates the pressure inside the manifold. Manifold pressure is a measure of the airflow into the engine cylinders at a given speed and intake air temperature. Thus, when combined with the engine’s rpm, manifold pressure is an indication of the engine’s power output.

a valve placed in a series of piping (a manifold). For example, in a choke manifold on a drilling rig, an adjustable choke, which is placed in the manifold, is one of several types of manifold valve that may be present.

in instrumentation, an action, such as rate of flow, that changes the control variables. For example, the rate of flow can be sensed and manipulated by electronic devices to control other process variables, such as pressure, temperature, and liquid level. When used in this manner, rate of flow is the manipulated variable.

a U-shaped piece of glass tubing containing a liquid (usually water or mercury) that is used to measure the pressure of gases or liquids. When pressure is applied, the liquid level in one arm rises while the level in the other drops. A set of calibrated markings beside one of the arms permits a pressure reading to be taken, usually in inches or millimetres.

the hot, plastic part of the earth that lies between the core and the crust. It begins 5 to 30 miles (10 to 50 kilometres) beneath the surface and extends to 1,800 miles (2,900 kilometres).

in instrumentation, an operator-controlled process whereby the operator makes adjustments to maintain the desired value without any automatic feedback.

a welding process in which an electric arc melts and fuses the pipe ends with the metal of an electrode held by the welder. Also called stick welding.

see liquefied petroleum gas.

1. under TSCA, anyone who manufactures or imports for commercial purposes over 10,000 pounds per year of a substance listed on the TSCA inventory. 2. under HAZCOM, production and drilling companies are considered manufacturers of crude oil, natural gas, and other products and must maintain an MSDS for these products.

see manhole.

Maritime Administration.

a well that is approaching depletion of its natural resource to the extent that any profit from continued production is doubtful.

a gauge that makes a continuous graphic record of tide height in relation to time.

a string of casing used in drilling from offshore bottom-supported drilling rigs. It extends from the bottom of the conductor hole to a point into the air directly under the rig. The blowout preventer stack is nippled up on top of the marine conductor. It also serves to guide drilling and subsequent casing strings into the hole.

1. a triangular sea-level extension of land shaped like the Greek letter ∆ . 2. a depositional environment in which riverborne sediments accumulate as the flow energy of the river is dissipated in the ocean.

see lay-barge construction.

congressional act that provides for protection of all marine mammals.

a congressional act that implements Annex V of the International Convention for the Prevention of Pollution from Ships (MARPOL). Under the provisions of this act, all ships and watercraft (including all commercial and recreational fishing vessels) are prohibited from dumping plastics at sea. The law also severely restricts dumping other vessel-generated garbage and solid waste both at sea and in U.S. navigable waters.

congressional act that identifies marine environments of special national significance, provides authority for conservation of these areas, and enhances public awareness and wise use of the marine environment through educational programs and research. Sometimes called the Marine Sanctuaries Act or the Ocean Dumping Act.

see riser pipe.

see Marine Protection, Research, and Sanctuaries Act of 1973.

an oil spill cooperative formed by a group of U.S. oil companies. MSRC is a national, private, nonprofit organization that will provide response to catastrophic spills in certain U.S. waters. It is primarily geared to respond to large, open water spills.

a fitting on top of the subsea blowout preventers to which the riser pipe is connected.

see riser pipe.

see riser pipe.

an assembly of devices installed on a floating offshore drilling rig to maintain a constant upward force (tension) on the riser pipe, despite vertical motions (heave) caused by ocean movements.

a publication of the United States National Weather Service (NWS) that contains articles, news, and information about marine weather events and phenomena, storms at sea, and weather forecasts. It is published two times a year with a spring-summer issue and a fall-winter issue.

of or relating to the sea, shipping, sailing in ships, or living and working at sea; situated or living close to the sea.

an agency of the U.S. Department of Transportation (USDOT) whose mission is to strengthen the U.S. maritime transportation system to meet the economic and security needs of the United States. MARAD programs promote the development and maintenance of an adequate, well-balanced United States merchant marine, sufficient to carry the nation’s domestic waterborne commerce and a substantial portion of its waterborne foreign commerce, and capable of service as a naval and military auxiliary in time of war or national emergency. MARAD also seeks to ensure that the United States maintains adequate shipbuilding and repair services, efficient ports, effective intermodal water and land transportation systems, and reserve shipping capacity for use in time of national emergency. Address: 1200 New Jersey Avenue SE; Washington, DC 20590; (800) 996-2723; www.marad.dot.gov.

a distinctive, easily identified rock stratum, especially one used as a guide for drilling or correlation of logs.

a provision in a natural gas sales contract that allows one or both parties to renegotiate the sales price or terminate the contract if the contractual sales price no longer reasonably reflects the current market. There are many forms of market-out provisions with differing rights and effects.

see merchantable title.

costs incurred in making gas merchantable, such as compression, dehydration, or treating, and costs of transporting gas to the point of delivery to the purchaser. Sometimes called handling costs.

a semisolid or unconsolidated clay, silt, or sand.

the short name for the International Convention for Prevention of Pollution from Ships, 1973 and 1978. (MARPOL is not an abbreviation or acronym; rather it is a contraction of “maritime pollution.”) MARPOL is an international treaty negotiated under the auspices of the IMO and is made up of 5 Annexes, each of which addresses a different kind of ship-generated pollution. (Under the terms of the convention, offshore platforms are considered ships.) The responsibility for administration and enforcement of MARPOL is split between the flag state (the country where the ship is registered) and the coastal state (in the United States, the USCG is responsible). MARPOL has led to the promulgation and implementation of several U.S. laws. For example, the Marine Plastic Pollution Research and Control Act of 1987 implements Annex V of MARPOL.

a tractorlike vehicle the wheels of which are fitted with extra-large rubber tires for use in swamps.

a calibrated funnel used in field tests to determine the viscosity of drilling mud.

see funnel viscosity, kinematic viscosity.

a trademarked term for a rig weight indicator. See weight indicator.

maximum allowable surface pressure.

the quantity of matter a substance contains, independent of such external conditions as the buoyancy of the atmosphere or the acceleration caused by gravity.

a calculation of gas flow through an orifice meter where the quantity of the gas (independent of external conditions like temperature, pressures, or gravity) is determined; usually expressed in pounds mass per unit time.

an instrument that measures the rate of flow of a fluid in a system, based on the mass of the fluid. The measurement is expressed as mass per unit of time where mass is volume times density. This expression is then converted to volume per unit of time, such as gallons per minute, barrels per hour, or cubic metres per hour.

a device that measures the specific gravity or relative density of a gas by means of the separation of gaseous ions according to their differing mass and charge.

the depth of the solid desiccant bed, in a solid desiccant dehydration system, from saturation to initial adsorption.

a portable der­rick that is capable of being raised as a unit, as distinguished from a standard derrick, which 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. Oil workers and manufacturers often use the words “mast” and “derrick” interchangeably. Compare derrick.

normally considered to be the Person in Charge of a marine vessel.

a device that fits into the rotary table to accommodate the slips and drive the kelly bushing so that the rotating motion of the rotary table can be transmitted to the kelly. Also called rotary bushing. See kelly bushing, slips.

the valve on the choke line that is nearest to the preventer assembly. Its purpose is to control the flow through the choke line. See HRC valve.

the clutch that connects the compounding transmission on a mechanical-drive rig to the input shaft of the drawworks; disengages the prime mover from all motions of the crane.

on a drilling rig, the primary station that controls the operation of the blowout preventers and other well-control equipment. Also called primary control panel. Backup control panels are usually installed should the master panel fail, or should it become inaccessible. See driller’s BOP control panel.

a computer equipped with a modem to communicate with the surface control module.

see master valve.

a meter that is proved using a certified prover and then used to calibrate other provers or to prove other meters.

an oscillator that establishes the carrier frequency of the output of an amplifier or transmitter. See oscillator.

an electrical component, usually wired in parallel with other switches, that controls the flow of electricity in the circuit. When closed, the switch allows electricity to flow through the circuit. When open, no electricity can flow. When the master switch is open, other switches in the circuit do not operate.

a measuring tape that has been certified accurate at a specified temperature and tension by the NIST. It is used to calibrate a working tape. See strap, working tape.

1. a large valve located on the Christmas tree and used to control the flow of oil and gas from a well. Also called master gate. 2. the blind or blank rams of a blowout preventer (obsolete).

a heavy-bodied, paste-like coating often applied with a trowel to produce a thick film.

a type of bottom support for the legs of a jackup, generally used in areas where the sea-floor is very soft. Each leg of the jackup is connected to the mat, which is a steel frame that is relatively wide. The mat, since it is wide, prevents the jackup’s legs from penetrating the soft seafloor.

a calculation used to inventory the fluids produced from a reservoir and the fluids remaining in a reservoir. Using the equations of the calculation, the volume of original oil in gas in place, the amount of drive-water influx, forecasts of production rates for several years, and estimates of ultimate recovery can be made.

in oilfield equipment and tools, a measure of the equipment or tool’s strength—that is, its ability to be bent, stretched, compressed, or loaded without deformation or breaking.

a reference document prepared by the chemical manufacturer and required under HAZCOM to be kept with the material during shipment and distributed in the workplace for any employee who may work with that material. The information on the MSDS may take a variety of forms but it must include the identity of the chemical, chemicals, or mixtures as listed on the container label; the physical and chemical characteristics of the material; the physical hazards of the material; the health hazards of the material; the primary routes of entry into the human body; the permissible exposure limits, if available; whether the material has been found to be a carcinogen, a potential carcinogen, or is regulated by OSHA; any generally applicable precautions for safe handling; any generally applicable control measures; emergency first aid procedures; the date the MSDS was prepared; and the name, address, and telephone number of the material source or another responsible party who can provide additional information and emergency procedures for the material if necessary.

a person who oversees the acquisition of supplies, equipment, and other resources for a company or organization. This person’s duties may also include managing and controlling warehouse operations, ordering materials, and managing inventory. Also called materialsman, warehouse supervisor.

1. in rock, the fine-grained material between larger grains in which the larger grains are embedded. A rock matrix may be composed of fine sediments, crystals, clay, or other substances. The solid portions of a porous rock not including the pores themselves. 2. the material in which the diamonds on a diamond bit are set. 3. in mathematics, a rectangular array of numbers from vector space.

see matrix acidizing.

an acidizing treatment using low or no pressure to improve the permeability of a formation without fracturing it. See wellbore soak. Compare fracture acidizing.

anything that occupies space and can be perceived by one or more senses; a physical body, a physical substance, or the universe as a whole; something that has mass and exists as a solid, liquid, gas, or plasma.

air emission standards under CAA that require the best pollution prevention methods available in specific industry categories for major sources of hazardous airborne pollutants.

the total load that can be transported over a given distance, taking into account weight and volume.

the greatest pressure that may safely be applied to a structure, pipe, or vessel. Pressure in excess of this amount leads to failure or explosion.

the maximum amount of pressure that is allowed to appear on the casing pressure gauge during a well-killing operation. This pressure is often determined by a leak-off test and if exceeded can lead to formation fracture at the casing shoe and a subsequent underground blowout or broaching.

the maximum output of a system or unit (such as a refinery, gasoline plant, pumping unit, or producing well).

the producing rate of a well that brings about maximum volumetric recovery from a reservoir with a minimum of residual-oil saturation at the time of depletion. It is often used to mean the field production rate that will achieve maximum financial returns from operation of the reservoir. The two rate figures seldom coincide, however.

the provision in a gas sales contract that allows the price of gas to track the monthly increases allowed under the Natural Gas Policy Act of 1978.

the maximum permissible gauge measurement to which a railroad tank car may be loaded according to Interstate Commerce Commission regulations. Also called stop gauge.

the maximum voltage or current in a cycle of an AC circuit.

in oilwell cementing, the maximum ratio of water to cement that will not cause the water to separate from the slurry on standing.

the maximum height of waves observed over a given period.

the maximum pressure to which a pressure containment device can be exposed under operating conditions (usually the pressure setting of the pressure relief device).

in a capacitor, the largest amount of voltage that can be applied to the capacitor under normal operating conditions without damaging or destroying it.

thousands of barrels of oil per day.

Migratory Bird Treaty Act.

metal clad.

1,000 cubic feet of gas, commonly used to express the volume of gas produced, transmitted, or consumed in a given period.

1,000 cubic feet of gas per day.

an instrument that measures very low pressures by measuring the height of a column of mercury supported by the gas whose pressure is to be measured. It is capable of measuring pressures as low as 1 micrometre of height in the column of mercury. It is often used to check the accuracy of other instruments.

master control station.

millidarcy (pl, millidarcys).

see methyldiethanolamine.

see monoethanolamine.

the average of two or more observed values.

a measurement of draft resulting from the average of several draft readings taken between the bow and stern of a floating vessel. If the vessel has a straight keel, mean draft occurs at the midpoint of the waterline length. See draft.

mean force acting on a rig as a result of the effects of wind, waves, and current conditions.

a physical quantity, property, or condition that exists or is to be measured. This term is preferred to “input,” “parameter to be measured,” “physical phenomenon,” “stimulus,” and “variable.”

to obtain an accurate measurement of the depth reached in a well by measuring the drill pipe or tubing as it is run into the well.

to measure drill pipe or tubing as it is pulled out of the hole, usually to determine the depth of the well or the depth to which the pipe or tubing was run.

the total length of the wellbore, measured in feet along its actual course through the earth. Measured depth can differ from true vertical depth, especially in directionally drilled wellbores. Compare true vertical depth.

the quantity in gallons in a railroad tank car at ambient temperature.

the electrical, mechanical, pneumatic, or other variable applied to the input of a device. It is the analog of the measured variable produced by a transducer.

the physical quantity, property, or condition that is to be measured. Common measured variables are temperature, pressure, rate of flow, thickness, and velocity.

the discrepancy between the result of the measurement and the value of the quantity measured.

a person employed by an oil or gas transmission company whose primary responsibility is the maintenance and repair of metering equipment.

paper or readouts in a meter station that is automated, remotely controlled, and/or computerized. Also called delivery ticket, receipt ticket, run ticket.

1. directional and other surveying during routine drilling operations to determine the angle and direction by which the wellbore deviates from the vertical. 2. any system of measuring downhole conditions during routine drilling operations.

a system in which downhole conditions are monitored during the drilling of a well.

the portion of a displacement meter that contains the measuring element.

a special reel and power arrangement for single-stranded wireline to make depth measurements in a well. A calibrated wheel and roller assembly is used to measure the footage of wireline as it is lowered into the well.

1. the portion of a displacement meter that moves within the measuring chamber so as to divide the liquid into measured segments as the liquid passes through the meter. 2. the rotating member of a turbine meter, commonly referred to as the rotor.

in process control, the elements of a controller that sense, measure, and transmit to the controlling means either the value of the controlled variable or its deviation from the desired point.

the difference between the maximum and minimum values of a measuring instrument or of a quantity to be measured. This range is obtained under normal conditions and should not be affected by an error exceeding the maximum permissible error.

part of the pipeline system in which are found the orifice meter and recorder, volume controller, and temperature recorder.

a calibrated tank that, by means of weirs, float switches, pressure switches, or similar devices, automatically measures the volume of liquid run in and then released. Measuring tanks are sometimes used in LACT systems. Also called metering tanks or dump tanks.

an optional crew member who is an all-around repairer for the rig’s mechanical components.

in process control, a device that exerts a physical force to produce motion or movement to a different position. For example, a mechanical actuator in a process valve opens or closes the valve, or positions the valve’s opening by physically moving the valve’s stem.

a brake that is actuated by machinery (such as levers or rods) that is directly linked to it.

see makeup cathead, breakout cathead.

see pipe prover.

see mechanical rig.

a speed-control device on an engine. Mechanical governors consist of flyweights, springs, and mechanical connections to the engine’s speed control. Compare electrically-actuated governor, hydraulic governor. See governor.

a test required prior to initial injection and once every five years thereafter (at a minimum) for certain types of injection wells under SDWA. These tests evaluate the operational integrity of the well so that underground sources of drinking water will not be endangered. EPA defines mechanical integrity as no significant leak in the casing, tubing, and packer and no significant fluid movement into a USDW through vertical channels adjacent to the injection wellbore.

a percussion tool operated mechanically to give an upward thrust to a fish by the sudden release of a tripping device inside the tool. If the fish can be freed by an upward blow, the mechanical jar can be very effective. Also called a hydraulic jar.

a log of, for instance, rate of penetration or amount of gas in the mud, obtained at the surface by mechanical means. See driller’s log, mud log.

used in a foam system where the venturi device and the agitation device are in the same nozzle.

a procedure used to punch one hole at a time into the tubing string to circulate or to kill a well. Hydraulic jarring action fires a powder charge with enough force to drive a small button through the tubing, but not through the casing.

a drilling rig in which the source of power is one or more internal-combustion engines and in which the power is distributed to rig components through mechanical devices (such as chains, sprockets, clutches, and shafts). Also called a power rig. Compare electric rig.

a special device used to lower and pull riser joints on a floating offshore drilling rig using a subsea marine riser system. The tool duplicates a riser-joint connection, and is made up on the riser joint in the same way as another riser joint. The upper section of the handling tool is a standard drill pipe tool joint that is supported by the elevators during raising and lowering operations. See riser pipe.

equipment that uses the hoisting equipment on the rig to snub pipe in or out of the hole. Snubbing is putting pipe in the hole or taking it out of the hole when the pressure in the wellbore is so high that it can force the pipe out of the hole if it is not restrained (snubbed). Basic components of a mechanical snubbing unit are the control heads (special BOPs) and operating manifold, stationary and traveling snubbers, snub line, and balance weight.

a condition in which solid material such as sloughing shale, sand, or shale driven uphole by a blowout, or junk in the hole causes the drill stem to become stuck against the wall of the wellbore.

see nonconductive wireline.

see mechanical rig.

a packer that is actuated by raising, lowering, or rotating the work string on which it is run. Such packers are often deployed in multizone completions, during well tests, and for water shutoff. See packer.

a statistical measure of the midmost value, such that half the values in a set are greater and half are less than the median.

the process of obtaining baseline physicals for employees involved in emergency response or hazardous waste cleanup and monitoring their health at specified intervals. Under HAZWOPER, medical surveillance is applied to members of organized HAZMAT teams and hazardous materials specialists and any emergency response employee who exhibits signs or symptoms of exposure, or wears a respirator for thirty days or more a year, or is exposed to hazardous substances at or above the permissible exposure limits.

in meteorology, the front that separates cold air masses over Europe from warm air masses over North Africa. See front.

see high-pressure distribution system.

a weather forecast covering a week or less.

see methyl ethylene glycol.

the metric unit of service given by a hoisting line in moving 1,000 newtons of load over a distance of 1,000 metres.

one million pascals.

an instrument for measuring large amounts of resistance in a circuit or insulation. Its name comes from Mega Ohmmeter, a proprietary trade name.

1,000,000 ohms. Sometimes expressed as 106 ohms.

the temperature at which the solid and liquid states of a substance coexist in equilibrium. The melting point temperature of a substance is usually determined at normal atmospheric pressure.

nitrogen that is recovered from the atmosphere by sending air through several bundles of membranes that resemble straws. Oxygen and water vapor quickly penetrate the membrane and escape, which leaves only nitrogen to exit from the end of the membrane. Thousands of membranes are placed inside a stainless steel operating bundle, or canister.

a gas treatment process in which a polymeric film or membrane is used to separate the acid gas components.

a modular membrane separation unit mounted on a portable platform.

the curved upper surface of a liquid column, concave when the containing walls are wet by the liquid (negative meniscus) and convex when not (positive meniscus).

maximum efficiency rate.

a compound chemically similar to alcohol, but in which sulfur replaces oxygen in the chemical structure. Many mercaptans have an offensive odor; thus they are used as odorants in natural gas.

a crude oil in which the S&W content is not in excess of that allowed for purchase; therefore, it is salable.

a title free from material defects or grave doubts and reasonably free from litigation, which can be sold or successfully defended in court; a court of equity will compel the vendor to accept such a title as sufficient. Also called marketable title or good title.

a barometer that uses mercury to measure atmospheric pressure. Cistern barometers and siphon barometers are the two types of mercury barometer.

a device that directly measures differential pressure between two ports. In a sealed chamber, an inverted bell housing floats in a pool of mercury. Differential pressure moves the bell upward in the mercury to operate a pressure indicator.

a device used to measure bulk volume of core samples by measuring the amount of mercury displaced by a core sample.

equipment used to remove trace quantities of mercury present in the gas feed to the aluminum heat exchangers.

a high-intensity discharge lamp in which the gas is vaporized mercury. Starts with the arcing of argon gas between the main electrodes and gives off a blue-white light.

a north-south line from which longitudes and azimuths are reckoned.

along, belonging to, relating to, or like a meridian. See meridian.

a measure of the openings of a woven material, screen, or sieve; e.g., a 200-mesh sieve has 200 openings per linear inch. A 200-mesh screen with a wire diameter of 0.0021 inch (0.0533 millimetre) has an opening of 0.074 millimetre (74 microns), or will pass a particle of 74 microns. See micron.

a span from 230 to 65 million years ago, the era of the dinosaurs and the first mammals.

a prefix meaning after, along with, beyond, among, and behind. For example, metaphysics is beyond physics in that metaphysics studies phenomenon that is not in the purview of normal physics.

a point located somewhere on a line drawn vertically through the center of buoyancy of the hull of a floating vessel with the hull in one position (e.g., level) and then another (e.g., inclined). When the hull inclines to a new position, the center of buoyancy of the hull also moves to a new position. If a second line is drawn vertically through the new center of buoyancy, it intersects the first line at a point called the metacenter. Location of the metacenter is important because it affects the stability of floating vessels (such as mobile offshore drilling rigs).

the vertical distance between an offshore floating vessel’s center of gravity and its metacenter. See metacenter.

opaque crystalline material, usually of high strength, that has good thermal and electrical conductivity, ductility, and reflectivity.

a mercury removal system in which a reactive metal bonded to a support structure, such as carbon or alumina, forms a reactive metal sulfide.

in electricity, a bundle of several wire conductors, each of which is individually insulated, that is surrounded by a strong metal covering.

in an engine, a fuel filter that consists of several very thin metal discs stacked inside a housing. As fuel flows through the strainer, foreign matter in the fuel is trapped by the very small spaces between the discs.

see cementing basket.

the sum of the cross-sectional areas of all the wires in a wire rope or in a strand.

the path of electric current through the metallic portions of a corrosion cell.

a field-effect transistor whose gate is insulated from the semiconductor’s substrate by a thin layer of silicon dioxide.

a semiconductor with two electrodes whose resistance depends on the voltage flowing through it. Its resistance decreases as applied voltage increases. Also called a voltage-dependent resistor.

1. the science that deals with the methods employed to extract metals from their ores, to purify and alloy metals, and to create useful devices from metals. 2. The study of metals and their properties in bulk and at the atomic level.

a rock derived from preexisting rocks by mineralogical, chemical, and structural alterations caused by heat and pressure within the earth’s crust. Marble is a metamorphic rock.

the process in which rock may be changed by heat and pressure into different forms.

to change into a wholly different form or appearance; to transform. For exampl­e, lime­stone metamorphoses into marble.

a scientist who studies the Earth’s atmosphere and its patterns of climate and weather.

1. a device used to measure and often record volumes, quantities, or flow rates of gases, liquids, or electric currents. 2. in the metric system of measurement, the unit of length; it equals about 3.28 feet, 39.37 inches, or 100 centimetres. v: to measure quantities or properties of a substance.

see meter combinator.

see meter factor.

fluid meters coupled in parallel. The sum of the fluid measured by the meter bank represents the total fluid measured.

1. the operation by which meter readings are compared with an accepted standard. 2. adjustment of a meter so that its readings conform to a standard.

a device to enable the adjusting of a meter register to indicate true volume within acceptable tolerance.

the maximum or minimum rate of flow recommended by the manufacturer to maintain a designated accuracy.

the outer portion of a meter, which encloses the measuring chamber and other working parts.

see meter factor.

in gas measurement, a circular chart of special paper that shows the range of differential pressure and static pressure and is marked by the recording pens of a flow recorder in an orifice metering system. Charts are rapidly being replaced by electronic flow recorders.

a device or system for accumulating the registration of two or more meters so that their total may be shown on a single readout device. Also called meter accumulator.

a counting device, electrical or mechanical, coupled to the measuring element to register the indicated volume that has passed through the meter.

difference in a volume determined from separate meters measuring the same gas stream, occasioned by the fact that gas volumes in field operations are not precisely determinable.

a number used to correct a meter’s inaccuracy. The factor is derived by dividing the actual volume of liquid passed through a meter during proving by the volume registered by the meter. For subsequent metering operations, the actual throughput, or gross measured volume, is determined by multiplying the indicated volume registered on the meter by the meter factor.

see orifice fitting.

the maximum rate of flow recommended by the meter manufacturer or authorized by a regulatory body. The maximum rate is determined by considerations of accuracy, durability, and pressure drop.

in gas measurement, the orifice plate, orifice fitting, manifold, and flow recorder. Also called a meter run, meter station, orifice meter installation.

pulses per barrel. See pulse generator.

a general expression for the relationship between the volume registered by a meter and the actual volume that has passed through it. May refer to meter error, meter factor, meter accuracy, and so on.

a device for converting meter rotor movement into an electrical output signal.

the multiple passes or round trips of the displacer in a prover for purposes of determining a meter factor. v: to establish the meter factor by comparing meter throughput to a prover of known volume.

a device used to determine the accuracy of a meter. Two popular types are pipe provers and open tank provers. A pipe prover has a calibrated pipe that contains a known volume. A sphere displaces oil or liquid product through the pipe while the meter being proved registers the amount of oil or liquid displaced. The meter’s reading is then compared to the known volume in the pipe. An open tank prover is a calibrated tank that contains a known volume. Oil or liquid product is put into the tank while the meter being proved registers the amount. The meter’s reading is then compared to the known volume in the tank.

the procedure required to determine the relationship between the true volume of liquid measured by a meter and the volume indicated by the meter.

a device in a pipe prover that, when actuated by the displacer sphere, registers pulses sent from a pulse generator on the meter being proved. By reading the number of pulses the counter registers, the amount of oil or liquid product the meter registered as having passed through the prover can be determined. The amount the meter registered is then compared to the known volume of the prover to determine the meter’s accuracy. See meter prover, pipe prover.

any single prover volume measurement in a set of prover volume measurements required to prove a meter.

the instantaneous display of the number of units of volume or equivalent thereof read directly from a meter register.

an instrument that receives signals from a transmitter.

a device that accumulates and displays the indicated volume passed through a meter.

see meter installation.

the point in a gas gathering system at which a field measuring meter and accessories are situated.

a small platform fabricated from pipe or bar stock and steel plate onto which a meter and a manifold are mounted.

the volume of liquid at a given flow rate that passes through a meter without being measured.

see meter installation.

an important part of the primary element of an orifice meter installation that must create a known flow pattern for the fluid as it reaches the plate. It is the straight upstream pipe of the same size between the orifice and nearest pipe fitting and the similar downstream pipe between the orifice and nearest pipe fitting.

a thermometer located in a pipeline either immediately upstream or immediately downstream of the meter; used to determine the temperature of the liquid flowing through the meter.

in countries using the metric system of measurement, the equivalent of a footage contract in countries using the English system of measurement. See footage contract.

in process control, the instruments or recorders that monitor the quantity of variables in a process such as temperature, flow, level, and pressure. v: to measure quantities or properties of a substance.

a collection of pipe and fittings, a manifold, in which is mounted a meter for measuring fluid flow through the manifold. Usually a meter is mounted in a manifold so fluid flow is diverted into it for measurement.

a complete separator and volume meter integrated into a single vessel. Two-phase units separate oil and gas and meter the oil; three-phase units separate oil, water, and gas and meter the oil and water. See meter, metering.

see measuring tank.

see measurement technician.

a method of describing a piece of land that measures the boundaries by beginning at a well-marked reference point and following the boundaries of the land all the way around to the beginning point again. The description relies heavily on reference to natural or artificial but permanent objects (such as roads and streams).

a light, gaseous, flammable paraffinic hydrocarbon, CH4, that has a boiling point of -25°F (and is the chief component of natural gas and an important basic hydrocarbon for petrochemical manufacture).

the paraffin series of hydrocarbons.

the lightest alcohol, having the chemical formula CH3OH. Also called wood alcohol.

a glycol used for water dew-point control and refrigeration.

see M1.

lead-free antiknock compound added to gasoline. Compare ethyl tertiary butyl ether.

an alkanolamine used in tail-gas treating and hydrogen sulfide enrichment units for selectively removing hydrogen sulfide from gas streams containing carbon dioxide.

a dye that colors the reactive clays (bentonite and/or drilled solids) in a drilling mud sample for determining the percentage of clay in the sample.

the fundamental unit of length in the international system of measurement (SI). It is equal to about 3.28 feet, 39.37 inches, or 100 centimetres.

a decimal system of weights and measures based on the meter as the unit of length, the gram as the unit of weight, the cubic meter as the unit of volume, the liter as the unit of capacity, and the square meter as the unit of area. The international system of measurement (SI) is based on the metric system.

a measurement equal to 1,000 kilograms or 2,204.6 avoirdupois. In some oil-producing countries, production is reported in metric tons. One metric ton is equivalent to about 7.4 barrels (42 U.S. gallons = 1 barrel) of crude oil with a specific gravity of .0184, or 36° API. In the SI system it is called a tonne.

devices used to take measurements from the end of the pipeline to the termination point.

microfarad.

manufacturer’s abbreviation for microfarad; often stamped on the body of the capacitor.

a trademark name for multiple formation evaluation. See drill stem test.

milligram.

millihenry.

unit of conductivity. Compare ohm.

a silicate mineral characterized by sheet cleavage; i.e., it separates into thin sheets. Biotite is ferromagnesian black mica, and muscovite is potassic white mica. Sometimes mica is used as a lost circulation material in drilling, and as a dielectric (insulator) in electrical components such as capacitors.

a capacitor whose dielectric (insulating material) is made from mica. See capacitor, mica.

capable of forming micelles.

a method of improved oil recovery in which chemicals dissolved in water are pumped into a reservoir through injection wells to mobilize oil left behind after primary or secondary recovery and to move it toward production wells. The chemical solution includes surfactants or surfactant-forming chemicals that reduce the interfacial and capillary forces between oil and water, releasing the oil and carrying it out of the pores where it has been trapped. The solution may also contain cosurfactants to match the viscosity of the solution to that of the oil to stabilize the solution and to prevent its adsorption by reservoir rock. An electrolyte is often added to aid in adjusting viscosity. Injection of the chemical solution is followed by a slug of water thickened with a polymer, which pushes the released oil through the reservoir, decreases the effective permeability of established channels so that new channels are opened, and serves as a mobility buffer between the chemical solution and the final injection of water.

a round cluster of hydrocarbon chains formed when the amount of surfactant in an aqueous solution reaches a critical point. The micelles are able to surround and dissolve droplets of water or oil, forming an emulsion.

a space that is left as casing contracts back to its normal size after pulling away from cement in the annulus.

a special caliper log combined with a Microlog™. See caliper log, Microlog™.

a stable, translucent micellar emulsion of oil, one or more surface-active agents, water, and sometimes an electrolyte. A microemulsion is classed as an emulsion because it is a mixture of immiscible substances (oil and water) and because it can have oil-in-water and water-in-oil phases. It can also have a phase in which neither oil nor water is dispersed, however, but are alternated in layers. A microemul­sion has certain properties that are like a solution rather than an emulsion: it is optically clear rather than clouded, and it is stable, i.e., the oil and water do not separate. Microemulsions are used for chemical flooding of reservoirs. See chemical flooding, emulsion, solution.

one-millionth (10–6) of a farad. See farad.

a remnant or trace of an organism of a past geologic age that is so small that it can only be seen with a microscope.

a guard-electrode log that measures the resistivity of the flushed zone.

trade name for a special electric survey method in which three closely-spaced electrodes are pressed against the wall of the borehole to obtain a measurement of formation characteristics next to the wall of the hole.

1. a caliper for making precise measurements; a spindle is moved by a screw thread so that it touches the object to be measured. 2. an instrument used with a telescope or microscope to measure minute distances. 3. in the metric system of measurement, one-millionth of a meter.

a unit of length equal to one millionth part of a metre, or one thousandth part of a millimetre, or 0.000039 inch. Also called a micrometre.

paleontology dealing with fossils of microscopic size.

heavy-duty paper perforated with several very small holes (pores). Folded in accordion pleats, micropore paper often serves as a secondary filter element in an engine’s fuel system. Fuel passes through the pores, while the unperforated part of the paper stops dirt.

a single silicon chip on which the arithmetic and logic functions of a computer are placed.

a resistivity logging tool consisting of a spring device and a pad. While the spring device holds the pad firmly against the borehole sidewall, electrodes in the pad measure resistivities in mud cake and nearby formation rock. See resistivity well logging.

one millionth of a second.

a proprietary name for a logging tool that measures resistivity of the flushed zone of the formation adjacent to the wellbore.

moving in cable tools; used in drilling reports.

hydrocarbons in the middle range of refinery distillation, e.g., kerosene, light and heavy diesel oil, heating oil.

in tank sampling, a spot sample obtained from the middle of the tank contents.

taken on tanks that have a capacity larger than 1,000 barrels (159,000 litres) and that contain 10 feet (3 metres) or less of crude oil. One middle spot sample should be taken as near the center of the vertical column of oil as possible.

a company whose main business concerns processing, storage and transportation of oil and gas.

the movement of oil from the area in which it was formed to a reservoir rock where it can accumulate.

a bird that moves (migrates) from one place to another, usually in connection with changing seasons. During times of migration, such birds, especially those attracted to bodies of water, may choose to rest in a drilling rig’s reserve pit. To prevent harm to the birds, rig owners place netting over the pit so that they cannot alight in the liquid in the pit.

a congressional act that established treaties with Great Britain, Mexico, Canada, Japan, and the former Soviet Union to protect migratory birds and their habitats. MBTA authorizes fines and even imprisonment for operators who allow migratory birds to become injured in pits or open-topped tanks that contain oil, oil products, caustic materials, or contaminants, such as arsenic or boron, that are poisonous or hazardous to migratory birds.

a distance equal to 0.001 (1/1,000, or 10–3) inches.

see circular mil.

a measurement of the length of a wire or conductor based on its cross-sectional diameter; a wire that is 1 foot long and has a diameter of 0.001 inches is 1 mil-foot.

specifications for equipment and procedures purchased by U.S. military forces.

see oil-emulsion water.

a downhole tool with rough, sharp, extremely hard cutting surfaces for removing metal, packers, cement, sand, or scale by grinding or cutting. Mills are run on drill pipe or tubing to grind up debris in the hole, remove stuck portions of drill stem or sections of casing for sidetracking, and ream out tight spots in the casing. They are also called junk mills, reaming mills, and so forth, depending on their use. v: to use a mill to cut or grind metal objects that must be removed from a well.

a special mill made up on the bottom of an overshot to grind away the top of a damaged fish so that the overshot can engage the fish. See overshot.

to use a mill on the end of a workstring to remove a permanent tool or fish.

thin, dense oxide scale that forms on the surface of newly manufactured steel as it cools. Mill scale can become cathodic to its own steel base, forming galvanic corrosion cells.

pipe coated at the mill as opposed to pipe coated over the ditch in pipeline construction.

a pinned-end pup joint used to provide additional length and inside diameter necessary to accommodate a standard milling tool.

also called a milled-tooth bit or a steel-tooth bit. See steel-tooth bit.

also called milled bit or steel-tooth bit. See steel-tooth bit.

a measure of the diameter of an electrical wire or cable expressed in thousandths of an inch. For example, if a wire’s diameter is 0.1 inch, it is also 0.1 ×  1,000 or 100 milli-inches.

a unit of atmospheric pressure equal to one thousandth of a bar. See bar.

one-thousandth of a darcy.

one-thousandth of a henry, or 10–3 henrys.

in the SI system of measurement, one-thousandth of a litre. In analyzing drilling mud, this term is used interchangeably with cubic centimetre. A quart equals 964 millilitres.

a measurement unit in the SI system equal to 10-3 metre (0.001 metre). It is used to measure pipe and bit diameter, nozzle size, liner length and diameter, and cake thickness.

one-thousandth of an mho.

see burn shoe, rotary shoe.

the tool used in the operation of milling. See mill.

a standard measurement in the gas industry based on 60°F and 14.7 psia.

a measure of gas volume at 60°F and 14.7 psia per day.

an almost universal measurement of the production of oil from a reservoir. One barrel (bbl) is equal to 42 U.S. gallons; thus, 1 million bbl equals 42 million gallons.

millisecond.

one-thousandth of a volt.

minute.

a U.S. government agency that evaluates research in the causes of occupational diseases and accidents. It is responsible for administration of the certification of respiratory safety equipment. Address: 1100 Wilson Blvd.; Arlington, VA 22209-3939;(202) 693-9414 .

naturally occurring special lignite, e.g., leonardite, that is produced by strip mining from special lignite deposits. The active ingredient is the humic acids. Mined lignins are used primarily as thinners, which may or may not be chemically modified; however, they are also widely used as emulsifiers.

1. a naturally occurring inorganic crystalline element or compound with a definite chemical composition and characteristic physical properties such as crystal shape, melting point, color, and hardness. Most minerals found in rocks are not pure. 2. broadly, a naturally occurring homogeneous substance that is obtained from the ground for human use (e.g., stone, coal, salt, sulfur, sand, petroleum, water, natural gas).

the full mineral interest and rights in one acre of land.

the legal instrument that conveys minerals in place together with the rights to search for and produce them.

rights and interests in the minerals found on or beneath the surface of land, created when the owner severs or separates his or her interests in the property.

owner of the rights and interests in a mineral estate (where interests in a landed estate have been severed). Compare surface owner.

the rights of ownership, conveyed by deed, of gas, oil, and other minerals beneath the surface of the earth. In the United States, mineral rights are the property of the surface owner unless disposed of separately.

an agency of the U.S. Department of the Interior that establishes requirements through the Code of Federal Regulations (CFR) for drilling while operating on the Outer Continental Shelf of the United States. The agency regulates rig design and construction, drilling procedures, equipment, qualification of personnel, and pollution prevention. Address: 1849 C Street NW, Mail Stop 4230; Washington, DC 20240; 202-208-3935.

a well completion in which the production casing is less than 4.5 inches (11.43 centimetres) in diameter. Compare conventional completion.

on floating offshore rigs using a marine riser system and a subsea blowout preventer stack, a device used to connect the choke and kill lines from the blowout preventer to the lower marine riser package’s connector. A miniconnector has a pressure rating of 15,000 psi (105,000 kPa) and an inside diameter of 3 inches (76.2 millimetres). See lower marine riser package.

see pad resistivity device.

a measure of the strength of a wire rope. Minimum acceptance strength is 2 percent lower than the catalog or nominal strength. See nominal strength.

the lowest internal pressure at which permanent distortion of pipe occurs.

the velocity that exists at the lowest operating flow rate, excluding those rates that occur infrequently or for periods of less than five minutes.

the lowest load imposed on the polished rod throughout a complete sucker rod pump cycle.

a royalty payment amount to be made regardless of the rate of production. The excess of such payments over regular royalty is chargeable against future production, if any, accruing to the royalty interest.

the stress level of tubular drill pipe above which permanent deformation will occur.

a form of joint venture very similar to an oil and gas joint operating agreement. Profits, losses, operations, and ownership are all shared, and the partners are jointly as well as severally (separately) liable.

in mathematics, the quantity from which another quantity is to be subtracted. For example, in the expression 38 – 23 = 15, 38 is the minuend.

see inverting input.

in process control, the frequency, in minutes, with which a proportional-plus-reset control system changes the final control element to correct for differences in the desired result. The proportional-plus-reset control system constantly monitors the process for deviation from the set point and performs corrections in discrete time intervals to maintain the set point.

moving in rig; used in drilling reports.

the capability of mixing together to form a single homogeneous phase. For example, alcohol and oil are miscible, but water and oil are immiscible (not miscible). Certain fluids, such as carbon dioxide and reservoir hydrocarbons, are immiscible on first contact but can become miscible after multiple contacts under suitable reservoir conditions of temperature and pressure. This situation is termed conditional, dynamic, or multiple-contact miscibility.

the pressure at which a gas injected into a reservoir vaporizes hydrocarbons from crude oil to form a miscible transition zone between the gas and the crude oil. This liquid transition zone moves reservoir oil toward production wells. Miscibility pressure depends on the characteristics of the gas and the temperature and gravity of the reservoir crude oil. For carbon dioxide, hydrocarbon vaporization begins at pressures between 1,000 pounds per square inch (6,895 kilopascals) and 2,000 pounds per square inch (13,790 kilopascals) at temperatures below 200°F (93.3°C) with oils above 30°API. Several hundred additional points per square inch are required to reach the optimum miscibility pressure, at which sufficient hydrocarbons are vaporized to produce a profitable amount of oil.

1. capable of being mixed. 2. capable of mixing in any ratio without separation of the two phases.

see miscible drive.

a method of enhanced recovery in which various hydrocarbon solvents or gases (such as propane, LPG, natural gas, carbon dioxide, or a mixture thereof) are injected into the reservoir to reduce interfacial forces between oil and water in the pore channels and thus displace oil from the reservoir rock. See chemical flooding, gas injection, micellar-polymer flooding.

see miscible drive.

an enhanced recovery method in which a gas is injected into reservoir that mixes with (is miscible with) the hydrocarbons in the reservoir. See enhanced oil recovery.

a method used in secondary recovery of fluids from a reservoir by injecting fluids that are miscible with reservoir fluids.

an air or gas drilling fluid that consists of 97 to 99 percent air or gas and 1 to 3 percent liquid (usually water). The liquid is not emulsified in the air or gas.

a drilling technique that uses air or gas to which a foaming agent has been added. Also called foam drilling. Underbalanced drilling in which mist is used as the drilling fluid. See mist, underbalanced drilling.

a metal device used to remove small droplets of moisture or condensable hydrocarbons from a gas stream in an oil and gas separator. The small droplets of moisture collect on the metal surface to form larger drops, which are removed from the separator along with other separated liquids.

mechanical integrity test.

to prepare drilling fluids from a mixture of water or other liquids and any one or more of the various dry mud-making materials (such as clay, weighting materials, and chemicals).

see field-grade butane.

1. a geological formation that contains gas entrained in (mixed with) liquids, such as oil and water, in the formation. 2. on an accumulator (blowout preventer operating unit), one of two containers (reservoirs). One reservoir stores the fluid concentrate and the other stores the mixed fluid. Using two reservoirs doubles the storage capacity of the accumulator.

in diving, oxygen and one or more inert gases.

a combination of straight-run and cracked naphtha.

a combination string. See graded string.

a tide that has characteristics of both semidiurnal and diurnal tides.

the heavier fractions of some crude oils that contain considerable amounts of both paraffins and asphalt.

diving in which a diver uses a breathing medium of oxygen and one or more inert gases synthetically mixed.

preparation of drilling fluids from a mixture of water and other fluids and one or more of the various dry mud-making materials such as clay and chemicals.

any tank or vessel used to mix components of a substance (as in the mixing of additives with drilling mud).

a valve to which fluids with different characteristics are routed to obtain a fluid that combines the characteristics of the original fluids. For example, a cold fluid and a hot fluid may flow through a mixing valve to achieve a median temperature between the two extremes.

1. a physical combination of two or more elements or components that maintain their chemical identity; no chemical reaction is involved. 2. under OSHA, any combination of two or more chemicals if the combination is not, in whole or in part, the result of a chemical reaction.

megajoule.

millilitre.

multilateral well.

millimetre.

millions of barrels of oil per day.

square millimetre.

cubic millimetre.

millions of barrels per day.

one million Btus.

million cubic feet; a common unit of measurement for large quantities of gas.

magnetomotive force.

man-machine interface.

Minerals Management Service.

million standard cubic feet. The standard referred to is usually 60°F and 1 atmosphere (14.7 pounds per square inch) of pressure, but it varies from state to state.

million standard cubic feet per day.

moving out; used in drilling reports.

a submersible offshore drilling rig designed to drill in the ice-choked waters of the arctic. It consists of a caisson base, which is a large concrete or steel tube, that rests on the seafloor. The drilling equipment is installed on top of the caisson above the water (ice) line. The caisson is built to withstand the enormous force of moving pack ice.

a formation that squeezes into the wellbore because overburden forces compress it. When a hole is drilled through such a formation, overburden pressure can cause the formation to reduce the size of the wellbore if the hydrostatic pressure of the drilling fluid is not sufficient to prevent it.

a drilling rig that drills offshore exploration and development wells. It floats on the surface of the water when being moved from one well site to another, but 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 off­shore drilling rigs and floating drilling rigs. Bottom-supported units include jackups, and floating rigs include semisubmersibles and drill ships.

a movable, reusable structure, such as a converted jackup drilling rig, from which offshore wells are produced. The main advantage over a conventional fixed or compliant platform is that MOPUs are less expensive.

a measure of the ease with which a fluid moves through a reservoir. Mobility is measured by dividing a formation’s permeability to a fluid by the fluid’s viscosity.

a polymer-water solution used in micellar-polymer flooding as a zone of viscosity transition between the initial injection of surfactant-water solution and the final injection of drive water. The lead edge of the polymer solution has a mobility equal to or less than that of the surfactant solution, and the trailing edge has a mobility close to that of water. This buffer zone prevents the drive water from fingering past the surfactant solution and thus reducing sweep efficiency. See micellar-polymer flooding.

the ratio of the mobility of a driving fluid (water or a chemical solution) at residual oil saturation to the mobility of the driven fluid (oil) at connate water saturation. The mobility ratio affects the sweep efficiency of an improved recovery project.

in process control, a given condition of functioning; a status. For example, a process system may be operating in the dump mode, wherein the system is removing liquid from a vessel to achieve a desired lower level.

a description or analogy used to help visualize something that cannot be observed directly, such as the structures, porosities, and permeabilities of a geological formation.

a brand of a hydraulic connector used in subsea blowout preventer stacks that uses individual hydraulic cylinders located in the connector’s lower body to operate an actuator ring. The connector has nine cylinders, six of which are primary, and three of which are secondary.

in the Beaufort wind scale, a wind whose speed is from 28 to 33 knots (32 to 38 miles per hour or 52 to 61 kilometres per hour). See Beaufort scale.

a cement whose properties, chemical or physical, have been altered by additives.

mobile offshore drilling unit.

work-over equipment designed in equipment packages or modules that are light enough to be lifted onto an offshore platform by a platform crane. In most cases, the maximum weight of a module is 12,000 pounds (5,443 kilograms). Once lifted from the work boat, the rig can be erected and working within twenty-four to thirty-six hours.

in electronics, to vary the amplitude, frequency, or phase of a signal’s wave. Modulating a wave with electronic information enables the wave to carry the information over a distance. A receiver, when tuned to the correct frequency, can demodulate the wave to make the information available for interpretation and understanding.

the ratio of the increment of some specified form of stress to the increment of some specified form of strain, such as bulk modulus, shear modulus, or Young’s modulus. Also called coefficient of elasticity, elasticity modulus, elastic modulus.

megohm, or 1,000,000 ohms.

a type of connector used at wire/chain interfaces used in a combination wire/chain system.

mole.

the volume occupied by one mole of a substance.

a thick sequence of soft, ungraded, cross-bedded, fossiliferous marine and terrestrial conglomerates, sandstones, and shales derived from the erosion of growing mountain ranges.

the vertical distance from the baseline of a ship or offshore vessel to the underside of the deck plating at the side, measured at the mid-length of the vessel.

the dimensions of a vessel to the molded lines.

the depth of the vessel below the waterline, measured vertically from the baseline to the waterline.

the lines defining the geometry of a hull as a surface without thickness.

the volume of a compartment without deduction for internal structure or fittings.

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, H2O, has a molecular weight of approximately 18. Therefore, a gram-mole of water is 18 grams of water; a pound-mole of water is 18 pounds of water. See molecular weight.

the ratio of the number of moles of one substance to the total number of moles in a mixture of substances, multiplied by 100 (to put the number on a percentage basis).

a more accurate term for molecular weight. See molecular weight.

synthetic zeolites packaged in bead or pellet form for (1) use in recovering contaminants or impurities from liquid and vapor product streams by selective adsorption and (2) use as a catalyst. Also called mol sieve.

the sum of the atomic weights in a molecule. For example, the molecular weight of water, H2O, is 18, because the atomic weight of each of the hydrogen molecules is 1 and the atomic weight of oxygen is 16. See mole.

the smallest particle of a substance that retains the properties of the substance. It is composed of one or more atoms.

a hard, silvery-white metallic element used to toughen steel and soften tungsten alloy. Its atomic number is 42; its atomic weight is 95.94. Molybdenum has a melting point of 2,617°C; a boiling point of 4,612°C; and a specific gravity of 10.22 at 20°C.

1. a turning effect created by a force, F, acting at a perpendicular distance, S, from the center of rotation. 2. the product of a force and a distance to a particular axis or point. 3. torque.

in relation to offshore floating rigs, a measure of the effectiveness of a force that consists of the product of the force and the perpendicular distance from the line of action of the force to the axis of rotation.

the sum of the products formed by multiplying the mass (or sometimes, the area) of each element of a figure by the square of its distance from a specified line. Also called rotational inertia.

see Monel steel.

a nickel-base alloy containing copper, iron, manganese, silicon, and carbon. Corrosion-resistant parts are often made of this material.

an instrument that reports the performance of a control device or signals if unusual conditions appear in a system. For example, an S&W monitor provides a mechanical means of preventing contaminated oil from entering the pipeline by detecting the presence of excessive water and actuating valves to divert the flow back to dehydration facilities.

the derrickhand’s working platform. As pipe or tubing is run into or out of the hole, the derrickhand must handle the top end of the pipe, which may be as high as 90 feet (27 metres) or higher in the derrick or mast. The monkeyboard provides a small platform to raise the derrickhand to the proper height for handling the top of the pipe.

rock strata that dip in one direction only. Compare anticline, syncline.

a colorless liquid, NH2(CH2)2OH, used in the purification of petroleum, sweetening natural gas, and the production of ethylene amines. Also called ethanolamine.

a chemical (an antifreeze) that is injected into lines and vessels to prevent hydrates from forming in the lines and vessels where hydrocarbon gases and water vapor are present at low temperatures. See hydrate.

a simple molecule capable of linking together as a repeating structural unit to form a polymer.

a seasonal wind caused primarily by differences in temperature between a land mass and an adjacent oceanic region. The wind blows from land to sea in the winter months and from sea to land in the summer months.

fog that may occur in summer monsoons where high humidity and large differences in temperature between land and surrounding oceans are present.

a clay mineral often used as an additive to drilling mud. It is a hydrous aluminum silicate capable of reacting with such substances as magnesium and calcium. See bentonite.

a walled hole or well in the hull of a drill ship, ship-shape barge, or semisubmersible drilling rig (usually in the center) through which the drilling assembly and other assemblies pass while a well is being drilled, completed, or abandoned.

of equipment installed through the moon pool of an offshore floating vessel. Using the rig to install subsea equipment eliminates the need for an additional lift vessel.

to fix a boat, ship, floating offshore rig, or other vessel to one place in the water with cables, chains, and anchors.

calculation performed as part of the design of a mooring system to establish mooring loads, tensions, and safety factors.

a place equipped with the necessary devices to allow a floating vessel, such as a ship, to tie up, or dock. In the oil industry, mooring facilities usually also have equipment to unload and temporarily store oil from tanker ships.

a cable, chain, or a combination of cable and chain that links a floating offshore rig or a ship to an anchor that grips the seafloor while the vessel is stationary. Offshore rigs usually employ several mooring lines and anchors.

force imposed on a mooring line in the direction of a mooring line as it enters a vessel’s fairlead.

margin of overpull.

mobile offshore production unit.

a mathematical formula that is of particular importance in evaluating hydrodynamic forces on structures in fluid media, such as water. Among other factors, the equation considers inertia, drag, the density of acceleration, and speed of water particles.

see daily drilling report.