Microbial Enhanced Oil Recovery-Laboratory Experiments with a Strain of Clostridium tyrobutyricum

It is well known that each microbial enhanced oil recovery (MEOR) method has its own selection criteria in order to match different reservoir conditions. Therefore successful application of MEOR method depends on the ability of microbes to adapt to extreme reservoir conditions and to produce the desired metabolic products needed for enhanced oil recovery. In this study, experiments have been performed with a strain of Clostridium tyrobutyricum. The experiments focused on salinity adaptation, gas production and the ability of microbes to modify rock properties. The result of the experiments showed that the strain of Clostridium tyrobutyricum adapted to 10, 30, 50, and 90 g/l before the start of the experiments produce more gas with an increase factor of between 0.39-6.9 for the same salinity condition than the pure culture. The adaptation process also led to the production of a strain 90F which can grow and produce metabolites at salinity range of over 90g/l. Strain 90F which is the adapted strain, frozen over a long period of time when activated were also able to attach to the oil water interface when grown inside test tubes at high salinity range. This can change the interfacial or wetting properties of the tubes. The mean porosity of carbonate rock samples increase from 42% to 48% when treated in microbial media leading to increase void ratio and the release of calcium ions; conditions that are favorable for biofilms formation in porous rock. These experimental results suggested that adaptation of microbes to high salinity conditions is possible and that pre-adaptation to reservoir conditions can ensure desired microbial activity needed to improve oil recovery.