METHOD FOR RECOVERING HEAVY/VISCOUS OILS FROM A SUBTERRANEAN FORMATION

摘要

Disclosed are methods for improving the production of heavy/viscous crude oilfrom subterranean formations com-prisingsecondary production through use of a displacement fluid (typically awaterflood) wherein the subterranean formation issubjected to cyclic periods of overinjection of the displacement fluidfollowed by underinjection of the displacement fluid, butkeeping the overall cumulative voidage replacement ratio (VRR) within adefined range, typically targeted to be about 1. In someaspects, the initial production of such heavy/viscous crude oil is limited, ifpossible, followed this cyclic secondary productionmethodology. By keeping the initial production, VRR, and cumulative VRR indefined ranges, the expected ultimate recovery(EUR) can be optimized, and overall production increased for example by asmuch as 100% or more relative to conventional pro-ductionmethods.