A Study of Foam Generation across Vertical Heterogeneity

Generation of foam has proved to be very effective as a conformance material when it is used in gas injection processes to improve recovery of oil. Many various studies have been performed and valuable conclusions have been drawn to augment understanding about foam generation process and its impact on ultimate recovery. However, a heterogeneous nature in vertical direction imposes a “threat” or an “opportunity” for generation process. This challenge indeed creates a need to investigate comprehensively, which essentially is the problem statement of this study. Therefore, the objectives of this study are to investigate the effect of vertical heterogeneity on foam generation during gas injection processes, analyze and discuss the influence of foam generation on gas mobility, and most importantly on ultimate oil recovery efficiency. The groundwork of this paper covers fundamental knowledge on foam generation in a porous medium, and effect of vertical heterogeneity upon it. This study seeks to accomplish its goal by using computer simulations, whereby simulation cases are prepared with respect to the paper objectives. The results suggest that foam generation was not beneficial when it was applied in the reservoir with low – permeability layer on top of the high – permeable one. It failed to challenge the conventional gas injection process with respect to case studies developed in the project, as very little or no strong foam was generated. By contrast, as the foam was generated in the reservoir with high – permeability on top, and low – permeable layer in the bottom, it succeeded to control the gas oil – ratio and mobility of injected gases quite effectively. Nevertheless, the most important benefit of foam was when it was generated at permeability contrast ratio of four, and foam proved to be even more beneficial to recover more oil at very abrupt contrast ratio of permeability between layers.