MARGINAL PROBABILITY OF HYDROCARBONS (MPHC) - The probability that oil and gas occur in commercial quantities, using existing recovery technology under current economic conditions.
MINIMUM ROYALTY - The lowest payment a lessee can pay on an OCS lease after production begins. It is equivalent to the yearly rental, typically $3 per acre or $8 per hectare. Rentals are paid annually before a discovery; royalties are paid on production after a discovery. If the total royalty payments amount to less than the yearly rental, the minimum royalty payments make up the difference.
MACARONI STRING - a string of tubing or pipe, usually 3/4 or 1 inch (1.9 or 2.54 centimeters) in diameter.
MAKE A CONNECTION - to attach a joint or stand of drill pipe onto the drill stem suspended in the wellbore to permit deepening the wellbore by the length of the pipe.
MAKE UP - 1. to assemble and join parts to form a complete unit (for example, to make up a string of drill pipe). 2. to screw together two threaded pieces. Compare break out. 3. to mix or prepare (for example, to make up a tank of mud). 4. to compensate for (for example, to make up for lost time).
MAKE UP A JOINT - to screw a length of pipe into another length of pipe.
MAKEUP CATHEAD - a device that is attached to the shaft of the drawworks and used as a power source for making up joints of pipe. It is usually located on the driller’s side of the drawworks. Also called spinning cathead.
MAKEUP TONGS - tongs used for screwing one length of pipe into another for making up a joint. Compare breakout tongs. See also tongs.
MALE CONNECTION - a pipe, coupling, or tool that has threads on the outside so that it can be joined to a female connection.
MANDREL - a cylindrical bar, spindle, or shaft around which other parts are arranged or attached or that fits inside a cylinder or tube.
MANIFOLD - 1. an accessory system of piping to a main piping system (or another conductor) 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.
MAST - 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.
MASTER BUSHING - 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.
MASTER VALVE - 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.
MECHANICAL JAR - 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.
MECHANICAL LOG - a log of, for instance, rate of penetration or amount of gas in the mud, obtained at the surface by mechanical means. See mud logging.
MECHANICAL RIG - 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.
MILL - a downhole tool with rough, sharp, extremely hard cutting surfaces for removing metal, packers, cement, sand, or scale by grinding or cutting.
MISCIBLE DRIVE - 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.
MIXING TANK - any tank or vessel used to mix components of a substance (as in the mixing of additives with drilling mud).
MIX MUD - to prepare drilling fluids.
MONITOR - an instrument that reports the performance of a control device or signals if unusual conditions appear in a system.
MONKEYBOARD - 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 meters) or higher in the derrick or mast.
MORNING TOUR - a work shift that generally begins at or near midnight. See graveyard tour.
MOTORHAND - the crew member on a rotary drilling rig, who is responsible for the care and operation of drilling engines. Also called motorman.
MOTOR - any of various power units, such as a hydraulic, internal combustion, air, or electric device, that develops energy or imparts motion. Compare engine.
MOUSEHOLE - shallow bores under the rig floor, usually lined with pipe, in which joints of drill pipe are temporarily suspended for later connection to the drill string.
MOUSEHOLE CONNECTION - the procedure of adding a length of drill pipe or tubing to the active string.
MUD - the liquid circulated through the wellbore during rotary drilling and workover operations.
MUD ACID - a mixture of hydrochloric and/or hydrofluoric acids and surfactants used to remove wall cake from the wellbore.
MUD CAKE - the sheath of mud solids that forms on the wall of the hole when liquid from mud filters into the formation. Also called filter cake or wall cake.
MUD CENTRIFUGE - a device that uses centrifugal force to separate small solid components from liquid drilling fluid.
MUD CLEANER - a cone-shaped device, a hydrocyclone, designed to remove very fine solid particles from the drilling mud.
MUD ENGINEER - an employee of a drilling fluid supply company whose duty it is to test and maintain the drilling mud properties that are specified by the operator.
MUD GAS-SEPARATOR - a device that removes gas from the mud coming out of a well when a kick is being circulated out.
MUD HOSE - also called kelly hose or rotary hose. See rotary hose.
MUD LINE - a mud return line.
MUD LOGGING - the recording of information derived from examination and analysis of formation cuttings made by the bit and of mud circulated out of the hole. A portion of the mud is diverted through a gas-detecting device. Cuttings brought up by the mud are examined under ultraviolet light to detect the presence of oil or gas. Mud logging is often carried out in a portable laboratory set up at the well site.
MUD PIT - originally, an open pit dug in the ground to hold drilling fluid or waste materials discarded after the treatment of drilling mud. For some drilling operations, mud pits are used for suction to the mud pumps, settling of mud sediments, and storage of reserve mud. Steel tanks are much more commonly used for these purposes now, but they are still usually referred to as pits.
MUD PUMP - a large, high-pressure reciprocating pump used to circulate the mud on a drilling rig. A typical mud pump is a two or three-cylinder piston pump whose replaceable pistons travel in replaceable liners and are driven by a crankshaft actuated by an engine or a motor.
MUD RETURN LINE - a trough or pipe that is placed between the surface connections at the wellbore and the shale shaker.
MUD TANK - one of a series of open tanks, usually made of steel plate, through which the drilling mud is cycled to remove sand and fine sediments.
MUD WEIGHT - a measure of the density of a drilling fluid expressed as pounds per gallon, pounds per cubic foot, or kilograms per cubic metre. Mud weight is directly related to the amount of pressure the column of drilling mud exerts at the bottom of the hole.
MULTIPLE COMPLETION - an arrangement for producing a well in which one wellbore penetrates two or more petroleum-bearing formations. In one type, multiple tubing strings are suspended side by side in the production casing string, each a different length and each packed to prevent the commingling of different reservoir fluids. Each reservoir is then produced through its own tubing string. Alternatively, a small diameter production casing string may be provided for each reservoir, as in multiple miniaturized or multiple tubingless completions. See dual completion.
LAND RIG - any drilling rig that is located on dry land.
LATCH - a device, usually with segmented threads, run with seal subs on the bottom of a tubing string and latched into a permanent packer to prevent tubing movement.
LAY - 1. the spiral of strands in a wire rope either to the right or to the left, as viewed from above. 2. a term used to measure wire rope, signifying the linear distance a wire strand covers in one complete rotation around the rope.
LAY DOWN PIPE - to pull drill pipe or tubing from the hole and place it in a horizontal position on a pipe rack. Compare set back.
LEAD-TONG HAND - the crew member who operates the lead tongs when drill pipe and drill collars are being handled. Also called lead-tong man.
LEAD TONGS - the pipe tongs suspended in the derrick or mast and operated by a chain or a wire rope connected to the makeup cathead or the breakout cathead.
LEASE - A legal document executed between a landowner, as lessor, and a company or individual (as lessee) that conveys the right to exploit the premises for minerals or other products for a specified period of time over a given area.
LIFTING - a threaded device placed in the end of tubulars, such as drill collars to aid in lifting; also called hoisting plug.
LIGHT ENDS - The more volatile products of petroleum refining, e.g., butane, propane, and gasoline.
LINER - 1. a string of pipe used to case open hole below existing casing. A liner extends from the setting depth up into another string of casing, usually overlapping about 100 feet (30.5 meters) above the lower end of the intermediate or the oil string. Liners are nearly always suspended from the upper string by a hanger device. 2. a relatively short length of pipe with holes or slots that is placed opposite a producing formation. Usually, such liners are wrapped with specially shaped wire that is designed to prevent the entry of loose sand into the well as it is produced. They are also often used with a gravel pack. 3. in jet perforation guns, a conically shaped metallic piece that is part of a shaped charge. It increases the efficiency of the charge by increasing the penetrating ability of the jet. 4. a replaceable tube that fits inside the cylinder of an engine or a pump.
LINER COMPLETION - a well completion in which a liner is used to obtain communication between the reservoir and the wellbore.
LINER HANGER - a slip device that attaches the liner to the casing. See liner.
LOCATION - the place where a well is drilled. Also called well site.
LOG - a systematic recording of data, such as a driller’s log, mud log, electrical well log, or radioactivity log. Many different logs are run in wells to discern various characteristics of downhole formation. v: to record data.
LOG A WELL - to run any of the various logs used to ascertain downhole information about a well.
LOGGING DEVICES - any of several electrical, acoustical, mechanical, or radioactivity devices that are used to measure and record certain characteristics or events that occur in a well that has been or is being drilled.
LONG STRING - 1. the last string of casing set in a well. 2. the string of casing that is set at the top of or through the producing zone, often called the oil string or production casing.
LOST CIRCULATION - the quantities of whole mud lost to a formation, usually in cavernous, pressured, or coarsely permeable beds. Evidenced by the complete or partial failure of the mud to return to the surface as it is being circulated in the hole.
LOST PIPE - drill pipe, drill collars, tubing, or casing that has become separated in the hole from the part of the pipe reaching the surface, necessitating its removal before normal operations can proceed; for example, a fish.
LOST TIME INCIDENT - an incident in the workplace that results in an injury serious enough that causes the person injured to be unable to work for a day or more.
LUBRICATOR - a specially fabricated length of casing or tubing usually placed temporarily above a valve on top of the casinghead or tubing head. It is used to run swabbing or perforating tools into a producing well and provides a method for sealing off pressure and thus should be rated for highest anticipated pressure.
