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Oil recovery experiments using Bacillus licheniformis JF-2 (ATCC 39307) and a sucrose-based nutrient were performed with Berea sandstone cores (permeability 0.084 to 0.503 "m [85 to 510 md]). Oil recovery efficiencies for four different crude oils (0.9396 to 0.8343 g/cm3 [19.1 to 38.1 ° API]) varied from 2.8% to 42.6% of the waterflood residual oil. Microbial systems reduced interfacial tension (IFT) ... 20 rnN/m [ ... 20 dyne/cm] for all oils tested. After the microbial flood experimentation, organisms were distributed throughout the core, with most cells near the outlet.

To study mechanisms by which microorganisms oxidize thiophenic sulfur in coal, we tested bacterial cultures for the ability to degrade dibenzothiophene (DBT), DBT-5-oxide, and DBT-sulfone and to modify water-soluble coal products derived from Illinois no. 6 and Ugljevik coals. In yeast extract medium, the majority of selected isolates degraded DBT and accumulated DBT-5-oxide in culture fluids; all but one of the cultures degraded DBT-5-oxide, and none of them degraded DBT-sulfone. Elemental analysis data indicated that the microbial cultures were able to decrease the amount of sulfur in soluble coal products derived from Illinois no. 6 and Ugijevik coals. However, these data suggested that microbially mediated sulfur removal from soluble Ugljevik coal occurred by nonspecific mechanisms. That is, extensive degradation of the carbon structure was concurrent with the loss of sulfur. This conclusion was supported by X-ray photoelectron spectroscopic data which indicated that the reduced sulfur forms in the soluble Ugljevik coal product was not oxidized by microbial treatment.

This report covers fiscal year 1991 research results for the Microbial Enhanced Oil Recovery (MEOR) and Wettability Research Program conducted by EG&G Idaho, Inc. at the Idaho National Engineering Laboratory (INEL) for the U.S. Department of Energy Idaho Field Office (DOE-lD). The program is funded by the Assistant Secretary of Fossil Energy, and managed by the DOE-lD and the Bartlesville Project Office (BPO). The objectives of this multi-year program are to develop MEOR systems for application to reservoirs containing medium to heavy crude oils and to design and implement an industry cost-shared field demonstration project of the developed technology. The program is inclusive of collaborative research efforts (established as subcontract agreements) in wettability with the New

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