| Summary: | A substantial amount of the world’s recoverable oil reserves comprise unconventional resources. However great difficulty has been encountered in recovering oil lower than 22° API. Therefore, advanced methods of Enhanced oil recovery (EOR) such as microbial enhanced oil recovery (MEOR) have been employed to increase the amount of recovered residual oil. MEOR involves the use of bacteria and their metabolic products to alter the oil properties or rock permeability within a reservoir in order to promote the flow of oil. Although MEOR has been trialled in the past with mixed outcomes, its feasibility on heavier oils has not been fully demonstrated. The aim of this study was to show that MEOR can be successfully applied to unconventional oil fields to increase oil production. Using both genomic and microbiologically applied petroleum engineering techniques, it was possible to target and isolate key indigenous microorganisms with MEOR potential from the reservoir of interest. In this study we have identified an indigenous microorganism (Bacillus licheniformis Bi10) that was capable of enhancing heavy oil recovery. This strain was applied to field specific microcosms and the effect of this microorganism was compared to variant inoculate, showing improved recovery beyond levels shown by previous MEOR related bacteria (Additional Oil Recovery- 11.8%). Furthermore, we also confirmed that the use of biosurfactant lichenysin alone was not as effective in MEOR compared to viable cell treatment, and hypothesized that a dual mechanism of action approach may be taking place within the microcosm, of both bio-plugging and wettability alteration. The interfacial tension of biosurfactant produced by the Bi10 isolate also showed a substantial decrease in wettability calculations, to < 5 mNm-1, lower than any other bacterial surfactants have been shown in heavy oil environments Comparative genomics also revealed key genetic variations between this and similar MEOR strains that could hold the key to its increased potential for future MEOR strategies. The results presented in this thesis were part of an ERDF project, involving academic and industrial partner, BiSN Laboratory Services, on fundamental and applied aspects of microbial enhanced oil recovery in heavy oilfield environments, which was funded to improve the understanding of MEOR and its processes in these unconventional oil environments.
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