Oil & Gas Terms in Category M


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).


A silicate mineral characterized by sheet cleavage; i.e., it separates in thin sheets.

Biotite is ferromagnesian black mica, and muscovite is potassic white mica.

Sometimes mica is used as a lost circulation material in drilling.

Make a connection

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 added (about 30 feet, or 9 meters).

Measure in

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.

Millidarcy (md)

One-thousandth of a darcy.

Modular-spaced workover rig

Workover 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 of 12,000 pounds.

Once lifted from the work boat, the rig can be erected and working within twenty-four to thirty-six hours.

Marginal well

An oil or gas well the production of which is so limited in relation to production costs that profit approaches the vanishing point.

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.

Make a hand

To become a good worker.

Measure out

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.

Multiple completion well

A well equipped to produce oil and/or gas separately from more than one reservoir.


A fishing tool used to recover a pared string of sucker rods from a well.

Mud acid

A mixture of hydrochloric and hydrofluoric acids and surfactants used to remove wall cake from the wellbore.

Metamorphic rock

A rock derived from preexisting rocks by mineralogical, chemical, and structural alterations caused by processes within the earth’s crust.

Marble is a metamorphic rock.

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 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.