STEAM-ASSISTED GRAVITY DRAINAGE HEAVY OIL RECOVERY PROCESS

摘要

A pair of vertically spaced, parallel, co-extensive, horizontal injecti on and production wells and a laterally spaced, horizontal offset well are provided in a subterranean reservoir containing heavy oil. Fluid communication is established across the span of formation extending between the pair of wells . Steam-assisted gravity drainage ("SAGD") is then practised by injecting ste am through the injection well and producing heated oil and steam condensate through the production well, which is operated under steam trap control. Cyclic steam stimulation is practised at the offset well. The steam chamb er developed at the offset well tends to grow toward the steam chamber of the SAGD pair, thereby accelerating development of communication between th e SAGD pair and the offset well. This process is continued until fluid communication is established between the injection well and the offset well. The offset well is then converted to producing heated oil and steam condensate under steam trap control as steam continues to be injected through the injection well. The process yields improved oil recovery rates with improved steam consumption.