Oil recovery process in subterranean formations

Abstract

Oil recovery from a subterranean, oil-containing formation having relatively highly permeable and/or fractured zones and relatively low permeability zones is improved by first injecting a predetermined amount of a plugging agent into the formation, preferably inorganic, non-polymeric solids suspended in a fluid such as drilling muds or bentonite or clay suspensions, that plugs the face of the highly permeable and/or fractured zones of the formation. Thereafter, injection of the plugging agent is continued or in the alternative a displacing fluid at a flow rate and pressure sufficient to initiate and propagate new fractures and/or extensions of existing fractures in the formation. Thereafter, a displacing fluid is injected into the formation at a pressure sufficient to maintain the new fractures and/or extensions of existing fractures open and displace oil from zones communicating with the new fractures and/or extensions of existing fractures toward a production well where it is recovered. Formation of the new fracture and/or extensions of existing fractures enables additional oil-containing zones in the formation to be swept by the displacing fluid thereby improving oil recovery.

Dependencies are inferred from the claim text.