gas cut mud

1. n. [Drilling]
Drilling fluid whose bulk, unpressurized density is reduced as a small volume of gas displaces an equivalent volume of liquid. The derrickman periodically measures mud density and communicates the results to the rig team via an intercom. He usually reports something like "9.6 heavy," "10.4," or "13.2 light," indicating more than 9.6 pounds per gallon, 10.4 pounds per gallon, or less than 13.2 pounds per gallon, respectively. Each tenth of a pound per gallon is referred to as a "point" of mud weight. Note that for this low-accuracy measurement, no direct mention of gas cut is made. A gas cut is inferred only if the mud returning to the surface is significantly less dense than it should be. In the case of the mud logger's measurement, "units" of gas (having virtually no absolute meaning) are reported. For the mud logger's measurement, a direct indication of combustible gases is made, with no direct correlation to mud weight.
Alternate Form: gas-cut mud