Prospects of microbial enhanced oil recovery: Mechanisms and environmental sustainability

The rise in petroleum demand may have aggravated recently as every industry heavily depends on petroleum as the primary energy source. Traditional oil recovery methods leave a large fraction of oil unrecovered in the inaccessible parts of reservoir. Hence, recovering the trapped oil using enhanced oil recovery (EOR) methods could be a solution to the rise in energy demand as well to maximize usage of an oil reservoir. EOR strategies include chemical, thermal, microbial, and miscible/solvent methods. Among these strategies, microbial enhanced oil recovery (MEOR) is a promising technique that is not widely discussed. This review paper presents overview of MEOR technology, types of microbial products (biosurfactants, biopolymers, biogases, bioacids, and solvents.) as well the mechanism involved in oil recovery. The focus of this paper is to analyze the different functions of the MEOR product, strategies, and their contribution to the recovery of residual oils. Other aspects such as developments on the applications, field operation parameters, reservoir screening criteria and high-yield recovery of oil from microbial are also studied. Lastly, challenges and future perspective of MEOR field are reviewed.