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

An electrode device with small spacings from which the current flow, and hence the measurement, is focused a short distance into the formation. Introduced in 1953, the microlaterolog measures the resistivity of the… Read more →

An unfocused electrode device with small spacings, mounted on a pad and pressed against the borehole wall. The typical microlog has one current-emitting electrode and two measure electrodes in line above it, one at 1… Read more →

The study of microfossils too small to be seen without the use of a microscope. Marine microfossils such as foraminifera are important for stratigraphic correlation. Read more →

That part of the pore space that has a characteristic dimension less than 1 micron. In general, this includes not only very small pores but also the porosity associated with surface roughness. The water in this pore… Read more →

Related to a log of the resistivity of the flushed zone recorded by a wirelineelectrode device. The device is mounted on a pad and pressed against the borehole wall. Several designs exist, for example microlog,… Read more →

An electrode device with small spacings from which the current flow, and hence the measurement, is focused a short distance into the formation. The microspherical log measures the resistivity of the flushed zone with… Read more →

A common term for the infinite-acting radial flow regime. This portion of the pressure-transient response is between wellbore-dominated flow regimes in the early-time transient data and boundary-dominated flow regimes… Read more →

The mountainous, linear axis of ocean basins along which rifting occurs and new oceanic crust forms as magma wells up and solidifies. The most prominent midoceanic ridges are those of the Atlantic and Indian Oceans. The… Read more →

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

A mathematical method of finding a central value for a group of data. The midrange is defined as the sum of the lowest value in the data set and the highest value if the data set divided by two. Read more →

A step in seismic processing in which reflections in seismic data are moved to their correct locations in the x-y-time space of seismic data, including two-way traveltime and position relative to shotpoints. Migration… 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 tool that grinds metal downhole. A mill is usually used to remove junk in the hole or to grind away all or part of a casing string. In the case of junk, the metal must be broken into smaller pieces to facilitate… Read more →

A downhole tool routinely used in fishing operations to prepare the top and outside surface of a fish, generally to allow an overshot or similar fishing tool to engage cleanly on the fish. In some cases, the outer… Read more →

On the basis of weight, the equivalent of parts per million, usually applied to small amounts of one solid admixed with another solid, such as 100 mg/kg of siderite in barite, the same as 100 ppm. Read more →

On a weight per volume basis, the SI unit of concentration, abbreviated mg/L, usually applied to dissolved material in a solution. This unit is used in water analyses and in mud and mud-filtrate analyses. Increasingly,… Read more →

The use of a mill or similar downhole tool to cut and remove material from equipment or tools located in the wellbore. Successful milling operations require appropriate selection of milling tools, fluids and techniques.… 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 crystalline substance that is naturally occurring, inorganic, and has a unique or limited range of chemical compositions. Minerals are homogeneous, having a definite atomic structure. Rocks are composed of minerals,… Read more →

Ownership of the right to exploit, mine or produce all minerals lying beneath the surface of a property. In this case, minerals include all hydrocarbons. Mineral interests include: 1. the right to use as much of the… Read more →

A small fracturing treatment performed before the main hydraulic fracturing treatment to acquire critical job design and execution data and confirm the predicted response of the treatment interval. The minifrac… Read more →

At constant temperature and pressure, the minimum quantity of additional components, such as intermediate-chain gases or CO2, that must be added to an injection gas to reach first-contact miscibility with a reservoir… Read more →

At constant temperature and composition, the lowest pressure at which first- or multiple-contact miscibility (dynamic miscibility) can be achieved. At minimum miscibility pressure, the interfacial tension is zero and no… Read more →

The smallest diameter present in a wellbore through which a tool string must pass to enable access to the operating depth or zone of interest. The minimum restriction determines the maximum tool string outside diameter… Read more →

An annotation made on a log print once every minute. By reading the depth interval between each minute mark, it is possible to check the logging speed. Minute marks are typically made by blanking out the vertical grid… Read more →

A situation in interpretation of seismic data in which predicted and actual values differ, or when an interpreted reflection does not close, or tie, when interpreting intersecting lines; or when interpreted seismic data… 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 →

A general term for injection processes that introduce miscible gases into the reservoir. A miscible displacement process maintains reservoir pressure and improves oil displacement because the interfacial tension between… Read more →

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