Using a liquefied gas as a centrifuge aid

Abstract

Extracting and separating solid particulates from a drilling fluid includes combining a stream of drilling fluid containing solid particulates with a liquefied gas to form a mixture having a reduced viscosity and/or density. The mixture enters a centrifugal separator at a pressure sufficient to keep the liquefied gas in a liquid phase where rotational forces promote the separation of at least a portion of the solid particulates from the mixture. At least a portion of the solid particulates are removed to form a fluid stream having reduced solids content. In embodiments the liquefied gas can be selected from the group consisting of an inert gas, an alkane gas, an alkene gas, an alkyne gas, a noble gas, and combinations thereof. The liquefied gas can be removed from the fluid stream after the centrifugal separator and recycled back to be mixed with the stream of drilling fluid containing solid particulates.