Abstract

Microbial Enhanced Oil Recovery has been known to the industry for decades and yet the research has only been applied to a selected few pilots where analysis of the in situ Microbes was made. The advent of Bio-Genetic Mapping of Microbes has introduced us to various strains of bacteria that can be genetically altered to produce alkali and surfactant needed in chemical floods in much higher concentration than previously thought. We conducted some initial experiments from which the enhancement of recovery factor is significant. The results and data generated were then used in STARSTM a compositional reservoir simulator to model the effect of various by-products (Polymer, Surfactants) generated by microbes on the recovery process. The surfactants generated lead to reduction of Interfacial tension from 30 to 0.1 dynes/cm2, the polymers were found to have properties as seen in natural polymers like Xantha and were resistive to salinity as well. The detailed report would be summarized in the paper. It is interesting to note that the different species of microbes used were anaerobic and was suited to survive at temperature of up to 600° F thus making it possible for them to survive harsh environments. Thus an overall promising outlook providing alternative to expensive chemical floods is being presented with special application to depleted reservoirs.

Introduction

Microbial Enhanced Oil Recovery is based on use of microbes for increasing recovery by reducing the interfacial tension by generation of in-situ surfactants, polymers to achieve favorable mobility ratio and other chemicals beneficial for the recovery process. Microbes have also been used in reservoirs known to have paraffin and asphaltene problems for well stimulation. The Microbes used are either developed in a culture in labs or microbes found in reservoirs are sampled and grown in labs and then injected into the reservoir with nutrients to further aid their growth in the reservoir. In certain cases microbes are known to give out gases like methane and CO2 which help in reduction of viscosity and mobilize oil which was earlier immobile. Recent studies into genome mapping of various species by researchers holds a promising future for the oil industry where the more than half of the oil is left in the reservoir and thus a potential target for MEOR.

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