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Investigation of Microbially Enhanced Oil Recovery for Alaska North Slope Heavy Oils

A. Ghotekar, K. Gerdes, S. L. Patil, A. Y. Dandekar, and M. B. Leigh
University of Alaska Fairbanks, AK, [email protected], [email protected], [email protected], [email protected], [email protected]

A large proportion of Alaska North Slope (ANS) heavy oil exists in the form of viscous deposits which cannot be entirely produced by conventional techniques. Microbially enhanced oil recovery (MEOR) is a promising approach for improving oil recovery for viscous deposits. MEOR can be achieved either ex situ such as flooding with microbial biosurfactants or injection of exogenous surfactant-producing microbes into the reservoir; or by in situ approaches such as biostimulation of indigenous surfactant-producing microbes in the oil. In this study, experimental work was performed to analyze potential application of MEOR to the ANS oil fields through both the ex situ and in situ approaches.

A microbial formulation containing a known biosurfactant-producing strain of Bacillus licheniformis was developed in order to simulate MEOR. Coreflooding experiments were performed to simulate MEOR for ANS heavy oils and quantify incremental oil recovery. Properties such as density, viscosity, and chemical composition were monitored before and after the treatment. Results indicate a post treatment reduction in the oil density and viscosity and there is degradation of heavier hydrocarbon components as evidenced by compositional analysis. The microbial formulation was found to significantly increase oil recovery, and the molecular and biological analyses indicated that the strain survived during the microbial treatment.

AAPG Search and Discovery Article #90088©2009 Pacific Section Meeting, Ventura, California, May 3-5, 2009