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How Do I Control the Density of Drilling Fluid?

Drilling fluid, commonly called "mud," serves several purposes in drilling wells with rotary rigs. Additives in the fluid help lubricate the bit and drill string, and constant circulation of the fluid within a well floats the cuttings--debris chipped loose by the bit--to the surface. A very important property of drilling mud is its density. The weight of the mud in the borehole prevents the escape of oil and gas that are under tremendous pressure at the bottom of the well. The density of drilling fluid is monitored constantly during drilling operations, especially in areas with known overpressured zones.

Things You'll Need

Drilling fluid
Fresh water
Mud balance
Density-control additives, including bentonite or barite

Instructions

- 1
  Capture a sample of clean drilling mud from the flow return line after cuttings have been removed by the shale shaker or conveyor system. Fill the receptacle of a mud balance with mud.
- 2
  Place the receptacle in the mud balance and adjust the scale until level. Read the mud density (pounds per gallon or kilograms per cubic meter) from the scale.
- 3
  Add fresh water as necessary to decrease mud density. Increase mud density by adding bentonite clay or dense material such as powdered barium sulfate (barite). Consult the charts and other references in a mud engineering handbook to calculate the mass of additive needed to change the overall density of the mud system.

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