Oil & Gas Terms in Category M

Makeup cathead

A device that is attached to the shaft of the drawworks and used as a power source for screwing together joints of pipe.

It is usually located on the driller’s side of the drawworks.

Also called spinning cathead.

See cathead.

Macaroni rig

A workover rig, usually lightweight, that is specially built to run a string of 3/4 inch or 1-inch tubing.

See macaroni string.

Make up a joint

To screw a length of pipe into another length of pipe.



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.


A pipe fitting with several side outlets to connect it with other pipes.


A fitting on an internal combustion engine made to receive exhaust gases from several cylinders.


Abbreviation: 1,000 cubic feet of gas, commonly used to express the volume of gas produced, transmitted, or consumed in a given period.


A portable derrick that is capable of being erected as a unit, as distinguished from a standard derrick that 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.

Compare derrick.


A round cluster of hydrocarbon chains formed when the amount of surfactant in an aqueous solution reaches a critical point.

The micelles are able to surround and dissolve droplets of water or oil, forming an emulsion.

Mill out

To use a mill on the end of a workstring to remove a permanent tool or fish.

Mist drilling

A drilling technique that uses air or gas to which a foaming agent has been added.

Mud circulation

The process of pumping mud downward to the bit and back up tot he surface in a drilling or workover operation.

See normal circulation, reverse circulation.

Make hole

To run casing or pipe.

Managed pressure drilling

An adaptive drilling process used to precisely control the annular pressure profile throughout the wellbore (iadc definition).


A clay mineral often used as an additive to drilling mud.

It is a hydrous aluminum silicate capable of reacting with such substances of magnesium and calcium.

See bentonite.


Describing a type of acoustic transducer that emits or receives energy in all directions.

Monopole transducers are used in standard sonic logs, and also in array-sonic logs to record shear and stoneley waves.

Mosquito bill

A tube mounted at the bottom of a sucker rod pump and inside a gas anchor to provide a conduit into the pump for well fluids that contain little or no gas.