Current Status of Nonthermal Heavy Oil Recovery

Abstract

ABSTRACT Heavy oils are an important resource worldwide, and yet two-thirds of the heavy oil deposits cannot be exploited by means of thermal recovery methods, because the effective energy production approaches energy input for reasons of formation thickness, depth, oil saturation and/or porosity. In such instances, especially if the heavy oil is not too viscous (below about 1000 centipoises), it may be economical to employ non-thermal recovery methods. These include polymer flooding, alkaline flooding, carbon dioxide (gaseous) floods, solvent floods, and other more specialized recovery methods, such as emulsion flooding, and combination techniques. This paper discusses non-thermal heavy oil recovery methods, based upon their application in the field. The processes and their mechanistic features are briefly discussed in the light of laboratory observations, which tend to be more optimistic than field results. The field tests, using non-thermal recovery are tabulated. This tabulation gives not only the reservoir rock and fluid characteristics, but also the reported test results, and any information on the economics of the respective tests. The salient injection-production data of each test are also considered. The data presented is designed to aid engineers in evaluating prospective field tests of the recovery methods considered. It is shown that at the present time carbon dioxide (gaseous) seems to hold considerable promise for the recovery of moderately viscous heavy oils. While laboratory results are encouraging, field experience using this technique is still limited. Several field tests in progress would provide more information in the next few years. The remaining methods have met with mixed success. One of the more widely favored methods - caustic flooding - has performed rather poorly in the field. It is concluded that given somewhat special conditions, nonthermal heavy oil recovery methods may be applicable to reservoirs considered to be marginal from the thermal recovery standpoint.