SG: 1.7 - 2.3
During drilling in Oil and Gas exploration, drilling mud or Bentonite is pumped into boreholes for multiple reasons. Pumping drill mud into boreholes cools the drill bit as well as bringing drill cuttings to the surface as the way in which mud is pumped into boreholes forms a closed loop system. The use of drilling mud also provides hydrostatic pressure to prevent liquids such as oil and gas rising to the surface, as drilling mud is thixotropic meaning when it is not agitated it stiffens forming a mud which is an effective liquid and gas barrier.
The consistency and application of drilling mud has a bearing on the mud pump specification. Centrifugal pumps may be used but progressing cavity pumps are the preferred option for high viscosity muds. Wear is also an important factor as positive displacement pumps will run slower resulting in less wear but lower flow rates.
Drilling muds can be water, oil or synthetically based. Water based muds and more environmentally friendly and used for the top section of any well, due to its proximity to the surface. Oil based muds are used for hard rock and utilize oils of low toxicity, and synthetic based muds are from non petroleum products with a pseudo plastic nature.