We investigated the decrease in oil viscosity caused by the biodegradation of crude oil by a bacterium (AR80) isolated from an oil reservoir, and estimated the potential for this bacterium for use in microbial enhanced oil recovery (MEOR). AR80 degraded long-chain n-alkanes preferentially, and anaerobically increased the ratio between the short-chain and long-chain n-alkane concentrations in the crude oil. The long-chain n-alkane metabolism by AR80 decreased the oil viscosity. AR80 grew well in a reservoir of brine supplemented with yeast extract, and decreased the oil viscosity to approximately 60 % of its original value. Adding a small amount of yeast extract (0.05 g/L) was necessary to stimulate the AR80 activity. MEOR can, therefore, be achieved using AR80 without incurring excessive costs. AR80 can grow at temperatures up to 80 °C and grows well at between 50 and 70 °C. AR80 can grow at a salinity of up to 90 g/L and grows well at a salinity of <30 g/L. The AR80 activity was not affected very much by high pressures (such as 6.0 MPa). Core flooding experiments were performed by injecting AR80 (in brine supplemented with yeast extract) into Berea sandstone cores. Gas chromatography analysis of the effluent oil suggested that long-chain n-alkanes in the residual oil were preferentially degraded by the AR80 in the porous rocks. The core flooding experiments showed that the AR80 activity in the porous rocks caused the oil recovery to be enhanced, so AR80 could be a suitable candidate for MEOR.
|Number of pages
|Journal of Petroleum Exploration and Production Technology
|Published - Jun 1 2014
All Science Journal Classification (ASJC) codes
- Fuel Technology
- Geotechnical Engineering and Engineering Geology