Drilling fluid Definition
1. 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.
Related Oil & Gas Terms
Centrifuge
1. a shake-out or grind-out machine. samples of oil are placed in the machine and whirled at high speed to settle out sediment. 2. an item of solids-removal equipment that removes fine and ultrafine solids. it consists of a conical drum that rotates at 2000 to 4000 rpm. drilling fluid is fed into one end and...
Plastic fluid
A complex, non-newtonian fluid in which the shear force is not proportional to the shear rate. most drilling muds are plastic fluids....
Desilter
A centrifugal device for removing very fine particles, or silt, from drilling fluids to keep the amount of solids in the fluid at the lowest possible point. usually, the lower the solids content of mud, the faster is the rate of penetration. the desilter work on the same principle as a desander. compare desander....
Mud
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...
Hydrostatic pressure
The force exerted by a body of fluid at rest. it increases directly with the density and the depth of the fluid and is expressed in pounds per square inch or kilopascals. the hydrostatic pressure of fresh water is 0.433 pounds per square inch per foot of depth (9.792 kilopascals per meter). in drilling, the...
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