Doctrines and realities in viscous and heavy-oil reservoir engineering

Abstract

Abstract Doctrines often develop with minimal empirical support. This observation is clear in reservoir engineering for heavy and viscous oils. Our objective is to develop a deeper appreciation of the empirical realities to permit improvement of recovery plans and thereby enable projects that are deemed uneconomic by the application of the misleading doctrines. Accordingly, this paper reviews the evidence for and against three doctrines in current use to develop recovery plans: (i) optimal recovery is obtained using a voidage replacement ratio (VRR\u202f=\u202finjected/produced volume) of 1, (ii) the Buckley-Leverett formulation applies uniformly to heavier oils, and (iii) viscous fingering dominates unstable multiphase flows. Of primary importance is the doctrine that optimal waterflood response is obtained for a VRR of 1 both on an instantaneous and cumulative basis. In the last decade, however, empirical, laboratory, and simulation investigations have demonstrated that, particularly for heavier oils, periods of VRR The appreciation of the empirical realities permits improvement of commercial recovery planning and enables a greater number of projects. These concepts are applicable in almost all viscous and heavy-oil reservoirs; they may also be applicable for lighter oils that possess oil chemistry that is typical of heavier oils, e.g., high acid content.