In Microbial Enhanced Oil Recovery (MEOR) oil mobility and oil recovery is increased by growing and reproducing microbes (bacteria) in oil reservoirs. The oil reservoir is either innoculated with a proprietry bacteria and then fed to grow or indigeneous microbes present are fed by the injection of a suitable nutrient identified from labotatory experiments. The metabolic by-products produced by these microorganisms causes a reduction in oil viscosity and interfacial tension and an increase in oil mobility. Although MEOR is not popular, the open literature has shown this to be a low cost mechanism that can be implemented with waterflood projects to increase the recovery of residual oil by another 1-5 %.

In this study an oil sample from an oil reservoir in the South of Trinidad was selected and the indigenous bacteria present was identified to be mainly of the Bacillus species. A quantification of this indigenous bacteria by plate counts showed that the aerobic colony forming units (CFU) was about 1.5×106 CFU/ml whereas the observed anaerobic plate counts was about 9.0×102 CFU/ml. Growth of the indigenous bacteria was stimulated by innoculating the oil sample with five different nutrient formulations for a period of three weeks so as to select the most suitable nutrient. However, the growth in bacteria was too numerous to count even after one week.

Experimental measurements showed that the sample innoculated with the nutrient broth formulation had the greatest change in oil properties. The reduction in oil viscosity was 49 % and the reduction in interficial tension was 17 %. The results from this study can be included in waterfloood simulation studies for suitable oil reservoirs in Trinidad to determine the added increase in oil mobility and oil recovery from a combination of waterflood and MEOR.

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