Microbial enhanced oil recovery, a critical review on worldwide implemented field trials in different countries

In recent years that reaching oil price to its minimum amount has become a critical issue in petroleum industry, microbial enhanced oil recovery (MEOR) is a main topic of interest in energy researches as an environment friendly and low operating cost treatment technology. Accordingly, it could be considered as an adequate alternative for conventional EOR techniques. The significant positive impact of MEOR technology in enhancement of oil recovery is established in both sandstone and carbonate reservoirs with different flow characteristics implemented all over the world. Unfortunately, in spite of its enormous benefits, MEOR is still not widely under investment due to lack of sufficient data. This paper presents the fully detailed update of MEOR field trials which exclusively investigates the field history performance of MEOR in different countries. This investigation includes 47 field trial cases in 21 countries in which the corresponded technologies, reservoir/formation names, microorganisms, nutrients and specific effects of each case are totally illustrated. Furthermore, microbial bioproducts and screening criteria parameters are widely demonstrated. A unique categorization of MEOR biosurfactants is also presented. In addition, different set of carried out experiments on biosurfactants along with their effects on IFT and residual oil recovery are examined. In fact, this review confirms the creditability of MEOR which creates strong perspectives to move toward more investment on this method.