Circulating fluid, one function of which is to force cuttings out of the wellbore and to the surface.
Other functions are to cool the bit and to counteract downhole formation pressure.
While a mixture of barite, clay, water, and chemical additives is the most common drilling fluid, wells can also be drilled by using air, gas, water, or oil-base mud as the drilling fluid.
2. any of a number of liquid and gaseous fluids and mixtures of fluids and solids (as solid suspensions, mixtures and emulsions of liquids, gases and solids) used in operations to drill boreholes into the earth.
Synonymous with “drilling mud” in general usage, although some prefer to reserve the term “drilling fluid” for more sophisticated and well-defined “muds.” classifications of drilling fluids has been attempted in many ways, often producing more confusion than insight.
One classification scheme, given here, is based only on the mud composition by singling out the component that clearly defines the function and performance of the fluid: (1) water-base, (2) non-water-base and (3) gaseous (pneumatic).
Each category has a variety of subcategories that overlap each other considerably.
synonyms: drilling mud, mud.