Possible Mechanisms in MIOR Processes

Abstract: Microbial Improved Oil Recovery, MIOR, consists in increasing the population of bacteria with beneficial properties for mobilizing additional oil in the reservoir, and thereby generating improved oil recovery (IOR). Determining which mechanisms allow bacteria to increase oil recovery and how these mechanisms occur and interact is the key to understanding, predicting and planning MIOR projects successfully. The authors have carried out experimental works with Rhodococcus sp. 094 and the main objective of the works was to get a better insight into the complex mechanisms allowing this bacterium species to increase oil recovery. This includes investigations of interfacial tension reduction, wettability changes due to the bacteria solution, glass micromodel flow tests and core flood experiments. From the results, it is possible to propose a theory of how Rhodococcus sp. 094 improves the oil recovery. The theory suggests which type of bacteria is most active and thereby gives IFT reduction, wettability alteration to both oil- and water-wet systems and gives favorable changes in the flow pattern.