Oil and Gas Terms Beginning with “M” — Page 5

The microlaterolog (MLL) is a focused resistivity wireline logging tool designed to measure the resistivity of the flushed zone — the reservoir rock immediately adjacent to the borehole that has been invaded by drilling… Read more →

What Is a Microlog? A microlog is a shallow-investigation resistivity logging tool that uses two closely spaced microelectrodes pressed against the borehole wall to measure near-borehole resistivity at two different… Read more →

Micropaleontology is the study of microfossils, the remains of organisms too small to be examined without a microscope, and it is one of the oldest and most cost-effective tools in petroleum exploration for dating and… Read more →

Microporosity refers to pore spaces in reservoir rock with diameters smaller than approximately 1-2 micrometers (microns) — pores so small that the fluids they contain are immobilized by capillary forces and cannot be… Read more →

A microresistivity log is a short-spacing resistivity measurement made by small electrode arrays or induction coils pressed directly against the borehole wall via a rigid pad, designed to measure the electrical… Read more →

The microspherical log (MSFL) is a focused pad-contact resistivity measurement device that reads the electrical resistivity of the flushed zone (Rxo) immediately adjacent to the borehole wall — typically within the… Read more →

Middle-time transient data (MTR) in pressure transient analysis refers to the time period during a pressure buildup or drawdown test when the wellbore pressure response reflects the undistorted radial flow of reservoir… Read more →

A mid-oceanic ridge is a continuous submarine mountain system extending approximately 65,000 km through every ocean basin along divergent plate boundaries, where magma upwells from the mantle to form new oceanic crust… Read more →

The halfway point between a seismic source and a receiver at the Earth's surface. Read more →

The midrange is a simple measure of central tendency defined as the arithmetic mean of the lowest and highest values in a data set: midrange equals the minimum plus the maximum, all divided by two. It is the midpoint of… Read more →

What Is Migration? Migration (also called hydrocarbon migration or petroleum migration) is the process by which oil and gas generated within a source rock move through permeable pathways in the subsurface toward zones… Read more →

A term used to describe an emulsion in a water-base mud in which the oil phase is internal (as in milk), and water is external. Read more →

A mill in oil and gas well operations is a downhole cutting tool — dressed with hard abrasive material (tungsten carbide, cubic boron nitride, or natural diamond inserts) on its working face — that is run on a… Read more →

A mill shoe (also called a junk mill shoe, reamer shoe, or guide shoe mill) is a downhole milling tool run on the bottom of a drill string or workover string to grind, cut, or dress metal objects and obstructions… Read more →

Milligrams per kilogram, abbreviated mg/kg, is a mass-based concentration unit expressing how much of one substance is present within a much larger mass of another, and on a weight basis it is numerically identical to… Read more →

Milligrams per liter (mg/L) is a unit of concentration expressing the mass of a dissolved or suspended substance in one liter of liquid solution — numerically equivalent to parts per million (ppm) for aqueous solutions… Read more →

Milling in petroleum well engineering is the use of a downhole rotary cutting tool (a mill) to grind, cut, and remove metallic or composite material from equipment or fish lodged in the wellbore — including sections of… Read more →

A common measure for gas volume. Standard conditions are normally set at 60oF and 14.7 psia, abbreviated MMscf. Read more →

A unit of measurement for the corrosion rate of a coupon, abbreviated as mpy. A mil is one thousandth of an inch. Read more →

A mineral in geology and petroleum engineering is a naturally occurring inorganic solid with a definite chemical composition and a crystalline atomic structure — with the rock-forming minerals quartz, calcite, dolomite,… Read more →

A mineral interest is the ownership of the right to exploit, mine, or produce all minerals lying beneath the surface of a property — including all hydrocarbons (oil, natural gas, condensate, natural gas liquids) as well… Read more →

A minifrac (also called a micro-frac, calibration fracture, or data frac) is a small-volume hydraulic fracture test performed before the main hydraulic fracturing treatment in a well — using a limited fluid injection… Read more →

Minimum miscibility concentration (MMC) is the lowest concentration of a miscible injectant component (typically an enriching gas component such as propane, ethane, or LPG intermediate hydrocarbons, or a first-contact… Read more →

What Is Minimum Miscibility Pressure? Minimum miscibility pressure (also called MMP) is the lowest reservoir pressure at which an injected gas achieves complete miscibility with reservoir crude oil, eliminating… Read more →

The minimum restriction in well intervention operations is the smallest internal diameter present in the wellbore through which an intervention tool string must pass to enable access to the operating depth or zone of… Read more →

A minute mark in wireline logging is a depth annotation made automatically on a continuous log print at one-minute intervals during the logging run, visible as a brief interruption, notch, or distinctive mark on one or… Read more →

A mis-tie in seismic processing and interpretation is an inconsistency in amplitude, phase, or timing between seismic reflection events recorded at the same subsurface point from two different seismic lines or surveys… Read more →

Pertaining to a condition in which two or more fluids can mix in all proportions and form a single homogeneous phase. Read more →

What Is Miscible Displacement? Miscible displacement (also called miscible flooding or miscible enhanced oil recovery) is an EOR process in which an injected fluid is fully miscible with reservoir oil at reservoir… Read more →

Small liquid droplets (moisture or liquid hydrocarbons) in a gas stream. In separators, mist extractors are used to collect mist. Read more →