Decanter centrifuge to Control Mud Viscosity in Weighted Water-based Drilling Mud

The purpose of the decanter centrifuge as applied to a weighted water-base drilling mud is to control viscosity. This is accomplished by concentrating the colloidal-size and clay-size solids fraction into the effluent (liquid) steam and disposing of this phase. The economic justification of using the centrifuge on this type of system is the simultaneous return of weight material. Using a centrifuge on weighted water-based muds eliminates the expense of throwing away (jetting) whole mud to control viscosity. Water dilution and excess waste volume are minimized.
* Add enough dilution water to reduce the effluent viscosity to 35-37 sec/qt marsh funnel viscosity. If the overflow is 37 sec/qt or less without dilution, none is needed.
* Operate the decanter centrifuge at a slower feed rate for longer periods to maximize efficiency and provide a more homogeneous mud system. It is better to run the centrifuge for eight hours processing 10 gpm than for four hours processing 20 gpm.
Weighted Oil-Base Muds

Single centrifuges have typically been run to control viscosity only on weighted water based muds. On an oil base mud solids control system, the cost of discarding the fluid phase and chemicals with the colloidal solids can be prohibitive.