Microbial Enhanced Oil Recovery (MEOR) is one of the technologies that can be potentially implemented with an exceptionally low operating cost: It has several advantages compared to conventional EOR processes as it does not consume large amounts of energy as do thermal processes, nor does it depend on the oil price as do many chemical processes. MEOR is simply the process of utilizing microorganisms and their bio-products to enhance the oil recovery. Bacteria are the only microorganisms used for MEOR by researchers due to their small size, their production of useful metabolic compounds such as gases, acids, solvents, bio-surfactants, biopolymers as well as their biomass. Also, their ability to tolerate harsh environments similar to those in the subsurface reservoirs in terms of pressure, temperature, pH and salinity increased their attraction to be used for EOR purposes.
MEOR MECHANISMS
Improving oil recovery through microbial actions can be performed through severl mechanisms such as reduction of oil water Interfacial Tension(ITF) and alteration of wettability by surfactant production and bacterial presence, selective plugging by microorganisms and their metabolites, oil viscosity reduction, degradation of long chain saturated hydrocarbons and production of acids which improves absolute permeability by dissolving minerals in the rock. The microorganism produces a variety of metabolites that are potentially useful for oil recovery.