A measure of the density of a drilling fluid expressed as pounds per gallon, pounds per cubic foot, or kilograms per cubic meter.

Mud weight is directly related to the amount of pressure the column of drilling mud exerts at the bottom of the hole.

The liquid circulated through the wellbore during rotary drilling and workover operations.

In addition to its function of bringing cuttings to the surface, drilling mud cools and lubricates the bit and drill stem, protects against blowouts by holding back subsurface pressures, and deposits a mud cake on the wall of the borehole to prevent loss of fluids to the formation.

See drilling fluid.

See shale shaker

See mud balance.

An employee of a drilling fluid supply company whose duty it is to test and maintain the drilling mud properties that are specified by the operator.

A record of information derived from examination of drilling fluid and drill bit cuttings.

See mud logging.

The recording of information derived from examination and analysis of formation cuttings made by the bit and of mud circulated out of the hole.

A portion of the mud is diverted through a gas-detecting device.

Cuttings brought up by the mud are examined under ultraviolet light to detect the presence of oil or gas.

Mud logging is often carried out in a portable laboratory set up at the well.

Any material added to drilling fluid to change some of its characteristics or properties.

1.

To seal the hole against formation fluids by allowing the buildup of wall cake.

2.

Block off the flow of oil into the wellbore.

Structure at the rig to store and shelter sacked materials used in drilling fluids.

Also called kelly hose or rotary hose.

See rotary hose.

To add solid materials (such as bentonite or other clay) to a drilling fluid composed mainly of clear water to obtain certain desirable properties.

Weight per unit volume of drilling fluid usually expressed in pounds per gallon or pounds per cubic foot.

See hydrostatic pressure.

A beam balance consisting of a cup and a graduated arm carrying a sliding weight and resting on a fulcrum.

It is used to determine the density or weight of drilling mud.

Instrument used to distill oil, water, and other volatile materials in a mud to determine oil, water, and total solids contents in volume-percent.