Modification of reservoir chemical and physical factors in steamfloods to increase heavy oil recovery. [Quarterly report], January 1--March 31, 1997

Thermal methods, and particularly steam injection, are currently recognized as the most promising for the efficient recovery of heavy oil. Despite significant progress, however, important technical issues remain open. Specifically, still inadequate is our knowledge of the complex interaction between porous media and the various fluids of thermal recovery (steam, water, heavy oil, gases, and chemicals). While, the interplay of heat transfer and fluid flow with pore- and macro-scale heterogeneity is largely unexplored. The objectives of this contract are to continue previous work and to carry out new fundamental studies in the following areas of interest to thermal recovery: displacement and flow properties of fluids involving phase change (condensation-evaporation) in porous media; flow properties of mobility control fluids (such as foam); and the effect of reservoir heterogeneity on thermal recovery. The specific projects are motivated by and address the need to improve heavy oil recovery from typical reservoirs as well as less conventional fractured reservoirs producing from vertical or horizontal wells. During this quarter, work continued on the development of relative permeabilities during steam displacement. Most of the work concentrated on the representation of the three-phase flow in terms of a double-drainage process. Work continued on the optimization of recovery processes in heterogeneous reservoirs by using optimal control methods. The effort at present is concentrating in fine-tuning the optimization algorithm as well as in developing control methodologies with different constraints. In parallel, we continued experiments in a Hele-Shaw cell with two controlled injection wells and one production well. In the area of chemical additives work continued on the behavior of non-Newtonian fluid flow and on foam displacements in porous media