Drilling fluid processing

Abstract

A method of processing a return oil-based drilling fluid includes centrifuging a primarily fluids phase at a first speed and separating the primarily fluids phase into a first effluent and a first residual, centrifuging the first effluent at a second speed and separating the first effluent into a second effluent and a second residual, and centrifuging the second effluent at a third speed and separating the second effluent into a third effluent and a third residual. A surfactant, a polymer, combinations of surfactant(s) and polymer(s) and/or a wash water may be added to one or more of the return oil-based drilling fluid, the primarily fluids phase, the primarily solids phase, the first effluent, the second effluent, and the third effluent.

Dependencies are inferred from the claim text.