Air-Foam-Injection Process: An Improved-Oil-Recovery Technique for Waterflooded Light-Oil Reservoirs

Abstract

Summary With the intent of solving problems that emerge at the later stage of waterflooded reservoirs, we study the feasibility of air-foam flooding of waterflooded light-oil reservoirs using the method of physical simulation. Through isothermal combustion experiments, the influence of clay mineral and foam on low-temperature-oxidation (LTO) reactions is investigated qualitatively. Then, the quantitative investigation of water saturation on oxidation rate and O2 consumption rate is discussed. After that, some dynamic foam displacement experiments are also performed, including the singletube displacement experiments of air foam at different water saturations and enhanced-oil-recovery (EOR) experiments of air-foam flooding in parallel tubes. In addition, in order to verify the O2 consumption capacity of the sample oil, a slimtube experiment is conducted. The results show that the presence of clay minerals could speed the process of the LTO reaction, while the presence of foam will slow this process. The LTO reaction is not significantly associated with oil viscosity. The concentration of O2 was near zero when the gas breakthrough occurred. Once the oxidation region reached the outlet, the concentration of O2 suddenly increased, and the effect of O2 consumption became worse. G64-38 crude oil performs better in the process of O2 consumption. The injection of air foam could effectively plug the high-permeability tube and restart the low-permeability tube. This paper could be used as a tool for the successful design of air-foam flooding at a later waterflood stage to enhance crude-oil recovery in light-oil reservoirs.