Oil and Gas Terms Beginning with “M” — Page 3

A mast unit is a self-contained well-servicing truck or trailer equipped with a hydraulic mast (a folding tower-like structure) used for slickline, electric wireline, and coiled tubing operations. The mast extends… Read more →

A master valve is the primary isolation valve positioned at the base of a wellhead's production tree (Christmas tree), directly above the tubing hanger, that provides the first and most critical shutoff point between… Read more →

What Is Material Balance in Reservoir Engineering? Material balance is a fundamental reservoir engineering method based on the conservation of mass: the volume of fluids produced from a reservoir must equal the… Read more →

What Is the Material Balance Equation? The material balance equation (MBE) is the fundamental reservoir engineering tool that quantifies the relationship between cumulative production, fluid expansion, water influx, and… Read more →

What Is the Material Balance Equation in Drilling Fluids? The material balance equation for drilling fluids is a set of mathematical relationships based on the principles that masses and volumes of mixture components… Read more →

The finer grained, interstitial particles that lie between larger particles or in which larger particles are embedded in sedimentary rocks such as sandstones and conglomerates. Read more →

What Is Matrix Acidizing? Matrix acidizing (also called matrix acid stimulation or acid matrix treatment) is a well stimulation technique in which acid is pumped into the formation at pressures deliberately kept below… Read more →

Matrix stimulation is a well treatment designed to restore or improve near-wellbore permeability by injecting treating fluid (usually acid) at pressures below the formation fracture pressure, so the fluid enters the… Read more →

What Is Maturation? Maturation (also called thermal maturation or source rock maturation) is the progressive thermal process by which organic matter preserved in fine-grained sedimentary source rocks is converted to… Read more →

Maturity in petroleum geochemistry refers to the thermal state of a source rock with respect to its progress through the kerogen-to-hydrocarbon transformation process — quantifying how far the source rock has progressed… Read more →

What Is a Maximum Flooding Surface? Maximum flooding surface (MFS, also called the surface of maximum transgression or simply the flooding surface) is the stratigraphic surface that marks the point of greatest landward… Read more →

The maximum recorded temperature (MRT) is the highest temperature value registered by a maximum-reading thermometer (a mercury-in-glass or bimetallic thermometer designed to retain the peak temperature reading after the… Read more →

Maximum treating pressure (MTP) is the highest wellhead or surface pump pressure allowed during a hydraulic fracturing, matrix acidizing, cementing, or other well stimulation or intervention operation that involves… Read more →

(noun) A statistical measure of central tendency, calculated as the arithmetic average of a set of values. In petroleum engineering, the mean is widely used in reservoir characterisation to summarise distributions of… Read more →

The measure point (MP) in directional drilling and well surveying is the specific location along the drill string or completion string where the survey instrument's sensor package physically resides when a directional… Read more →

Measured depth is the total distance along the actual wellbore path from the surface reference point, commonly the rotary table (RT) or kelly bushing (KB), to any downhole location, serving as the primary depth… Read more →

Measurement after drilling (MAD) refers to the process of retrieving and downloading formation evaluation data from downhole memory tools after the drill string has been tripped out of the wellbore, as opposed to… Read more →

The difference between the true value and that which is reported from a measurement. Read more →

Measurement range in oilfield instrumentation and sensor engineering is the span between the minimum and maximum values of a physical quantity that a measurement device is designed and calibrated to measure accurately,… Read more →

What Is Measurement While Drilling (MWD)? Measurement while drilling (MWD) describes the downhole instrumentation and surface telemetry system that transmits real-time wellbore survey data, including inclination,… Read more →

What Is MWD? Measurements while drilling (MWD) describes the acquisition of physical wellbore parameters — primarily trajectory (inclination, azimuth), pressure, and temperature — during active drilling using downhole… Read more →

A calibrated tank that automatically measures the liquid volume passing through it. Measuring tanks are also called metering tanks or dump tanks. Read more →

What Is Mechanical Diversion? Mechanical diversion is the use of physical isolation tools including bridge plugs, inflatable and compression-set packers, ball sealers, and straddle packer systems to hydraulically… Read more →

A mechanical jar is a downhole fishing and drilling tool that stores mechanical energy by stretching or compressing a spring-loaded or hydraulically damped telescoping mandrel within the drill string, and releases that… Read more →

Mechanical skin is the dimensionless pressure drop factor that quantifies the reduction in near-wellbore flow capacity caused by physical, non-chemical damage mechanisms in the formation around the wellbore, including… Read more →

Mechanical sticking is the limitation or complete prevention of axial motion (up-down) and rotational motion of the drillstring caused by a physical interaction between the drillstring and the wellbore wall or wellbore… Read more →

The median in petroleum engineering and geoscience is the middle value in a ranked dataset — the value at which exactly half of the observations fall below and half fall above — and serves as a robust measure of central… Read more →

Referring to any particle in the size range 74 to 250 microns. Read more →

Medium induction in wireline logging refers to the resistivity measurement from an induction tool that investigates the formation at an intermediate depth — approximately 40 to 80 centimeters from the borehole wall —… Read more →

What Is Membrane Potential? Membrane potential generates an electromagnetic force across ion-selective shale and clay boundaries when drilling mud and formation water have different salinities, producing the dominant… Read more →