Drilling Mud

Mixture of water and special additives circulating within the well for the purpose of cooling the drill-bit; removing rock cuttings and transporting them back up to the surface.
Also prevents the well wall from caving in and maintains sufficient pressure at the well bottom to avoid hydrocarbon blowout.
Further Reading

Manifold

A pipe spool in which a number of incoming pipes are combined to feed to a common output line.

Further Reading

MAWP

Maximum Allowable Working Pressure
The maximum pressure allowed in a piece of equipment e.g. vessel or pipe at its designated temperature.
Further Reading

MCC

Motor Control Centre / Switchboard

Further Reading

Mercaptan

Molecules containing sulphur with a low molecular weight and therefore very light.

Further Reading

MIPEG

An electronic load indicator and monitoring system fitted to cranes - can store data for future analysis and maintenance planning based on the actual crane usage.
Manufactured by Norwegian firm Datainstrument AS
Further Reading

MMI - Man Machine Interface

A dated term superseded by SCADA

Further Reading

MOB - Man Over Board

Some offshore platforms issue personnel with MOB detectors when performing over the side work.
These detectors automatically emit a signal when imersed in the sea thereby allowing possible faster rescue.
Further Reading

MOC

Management of Change

Further Reading

MODBUS

This Protocol is a messaging structure developed by Modicon in 1979.
It is used to establish master-slave/client-server communication between intelligent devices.
Further Reading

MOL - Main Oil Line

Name often given to the oil export line from a platform.
Often used as a prefix to the main export pumps e.g. MOL Pumps
Further Reading

Monel

A nickel-copper alloy which combines high strength with high ductility - these usually being a trade off in metals selection.
Also offers excellent general corrosion resistance. Commonly used in seawater applications.
Further Reading

MOU

Memorandum of Understanding

Further Reading

MOV

Motor Operated Valve

Further Reading

MPI

Magnetic Particle Examination. A form of NDE used to detect surface cracks on castings.

Further Reading

MTBF - Mean Time Between Failures

The time interval between 2 failures of a component. The reciprocal of the failure rate.

Further Reading

MTO - Material Take Off

A count of all materials needed to complete a task

Further Reading

MTTR - Mean Time To Repair

The average time taken from the failure of a system until it is successfully restarted.

Further Reading

Mux - Multiplexer

A switching device that sequentially connects multiple inputs or outputs in order to process several signal channels with a single A/D or D/A converter

Further Reading

MWD - Measurements While Drilling

The evaluation of physical properties (usually including pressure; temperature and wellbore trajectory in three-dimensional space) while extending a wellbore

Further Reading

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