Potential applications of microbial enhanced oil recovery to heavy oil.

Heavy oil accounts for around one-third of total global oil and gas resources. The progressive depletion of conventional energy reserves has led to an increased emphasis on the efficient exploitation of heavy oil and bitumen reserves in order to meet energy demand. Therefore, it is imperative to develop new technologies for heavy oil upgrading and recovery. Biologically-based technology that involves using microorganisms or their metabolites to mobilize heavy oil trapped in reservoir rocks can make a significant contribution to the recovery of heavy oils. Here, the results of laboratory experiments and field trials applying microbial enhanced oil recovery (MEOR) technologies are summarized. This review provides an overview of the basic concepts, mechanisms, advantages, problems, and trends in MEOR, and demonstrates the credibility of MEOR methods for applications in enhanced heavy oil recovery and the petroleum refining processes. This technology is cost-effective and environmentally-friendly. The feasibility of MEOR technologies for heavier oil has not yet been fully realized due to the perceived process complexity and a lack of sufficient laboratory research and field test data. However, novel developments such as enzyme-enhanced oil recovery continues to improve MEOR methods.HighlightsHeavy oil represents the largest known potentially-recoverable petroleum energy resource.Novel biotechnological processes are needed to recover or upgrade heavy oil.Microbial technologies have great potential for heavy oil recovery.Microorganisms can produce metabolic byproducts to mobilize oil trapped in reservoirs.More technological research is needed to develop microbial enhanced oil recovery.