Microbial Enhanced Oil Recovery: A Pore-Scale Investigation of Interfacial Interactions

Current oil production technologies recover only about one-third to one-half of the oil originally present in an oil reservoir. Given current oil prices, even a modest increase in oil recovery efficiency is fiscally attractive. One novel approach to increase oil recovery efficiency is a process called microbial enhanced oil recovery (MEOR), where microorganisms are either used as a clogging agent to redirect flow or to produce biosurfactant that reduces interfacial tension. This dissertation aims to understand the MEOR pore-scale mechanisms relevant to oil recovery by taking a two-fold approach where transparent 2-dimensional micromodel experiments imaged with stereo microscopy and 3-dimensional column experiments imaged with x-ray computed microtomography (CMT) are utilized. Micromodel experiments allow for direct visualization of the biological phase (i.e. biofilm), however, only 2-dimensional information is provided. Conversely, CMT experiments provide 3-dimensional pore-scale information, but lack the ability to image the biological phase. With this two-fold approach, it is possible to distinguish multiple fluid interfaces, quantify fluid phase saturations, measure oil blob size distributions, and visualize the biological phase. Furthermore, a method to measure interfacial curvature from 3-dimensional images is developed, providing researchers a new perspective from which to study multiphase flow experiments. Overall, the presented research utilizes pore-scale imaging techniques to study the interfacial interactions occurring during MEOR in an effort to better explain the physics, and thus, increase the efficacy of MEOR.