Bokor field was selected as the first field in Malaysia for Microbial Enhanced Oil Recovery (MEOR) technology application which utilizes micro-organisms to facilitate, increase or extend oil production from reservoir through the production of biochemical such as biosurfactant, solvents, gases and weak acids. The field was selected due to its high viscosity crude (4 to 10 cp) and low oil specific gravity of 20° API which could resulted in low recovery factor in major reservoirs ranges from 19% to 25% of its original oil in place. This technology also seems to be attractive for the field as it was initially thought to be potential for for reducing the viscosity of the oil and thus improve oil recovery. In addition, reservoir properties for major reservoirs in Bokor field conform to the basic screening criteria of the MEOR application.
This paper mainly discusses the results of the pilot project on MEOR technology application in Bokor field1 . A feasibility study focusing on candidate selection and comprehensive laboratory analysis was conducted to investigate the feasibility of this technology for improving oil production/recovery. Generally, the feasibility study had indicated that there is a potential oil production improvement with no near wellbore impairment. Biodegradation study on the crude sample indicates complete removal of normal/branched alkanes and partial removal of aromatics due to in-reservoir alteration. Laboratory inoculation on the wellhead crude sample indicated that the microbes were able to slightly reduce the viscosity, break the emulsion and increase the solubility of high molecular weight component without damaging the reservoir. In order to prove the laboratory results and further assess the impact to oil production, a pilot test on three (3) selected wells were carried out. A comprehensive monitoring strategy was developed and the performances were monitored for 5 - 6 months.
Over 5 months period, results from the pilot were found to be encouraging. Significant increase in oil production rate and reduction of water cut were observed demonstrating the effectiveness of MEOR application. The average oil production rate for the period increases by 270 b/d which is equivalent to 47% oil incremental.