High vertical conformance steam injection petroleum recovery method

Abstract

Viscous oil recovery methods employing well-to-well throughput steam injection are frequently less successful than anticipated because the process experiences poor vertical conformance, meaning that only a portion of the full vertical thickness of the oil saturated reservoir is contacted by the injected steam. Because the specific gravity of the vapor phase portion of saturated steam is substantially less than the specific gravity of formation petroleum fluids, the vapor phase steam channels across the upper portion of the formation and only contacts and displaces petroleum present in said upper portion of the formation, bypassing substantial amounts of petroleum in the lower portion of the formation. By separating saturated steam into two components, one predominantly liquid phase and one predominantly gaseous phase, and injecting the hot liquid into the upper portion of the formation and the vapor into the lower portion of the formation, substantially greater amounts of formation petroleum are contacted and recovered by steam. Steam may be separated into liquid and vapor phase components on the surface and injected by a separate flow path into separately completed intervals, or the separation may be accomplished in a downhole separator. The process may be applied using steam alone, or other gaseous and/or liquid phase additives to steam may be injected in the same manner.