Oil production increased in two test wells in a mature oil reservoir in Mann Field, Myanmar by successfully applying an enzyme-enhanced oil recovery (EEOR) process, a subset of microbial-enhanced oil recovery. A concentrated, water-soluble enzyme preparation made from DNA-modified proteins released from selected microbes was specifically prepared and injected in oil zones of one well and then recycled and applied in a second well.
Mann Field is a brownfield located in Salin sub-basin of the central basin of Myanmar in Southeast Asia and currently is operated by MOGE, with MPRL E&P Pte Ltd as the contractor for the field operations management. The field began producing in 1970, predominately from Oligocene reservoirs that consist of 26 stacked sandstone payzones. More than 667 wells have been drilled and completed, and 118 million stock tank barrels of oil have been produced. Average porosity of the field is 18% with an average permeability of 10-250 md. Oil gravity is typically 36.5°API, which is paraffinic in certain horizons, and the gas gravity is 0.65.
A test well was injected with 1 treatment of enzyme concentrate diluted to 2% in formation compatible, filtered brine. Pre treatment production was 14 bopd and 2 bwpd. Current production is 18 bopd, and some 530 incremental barrels have been produced in 13 months following treatment.
Pre treatment production from the second well was 10 bopd and 109 bwpd. Current production is 16 to 17 bopd, and approximately 1636 barrels of incremental oil has been produced during nine months since the treatment. Additional enzyme treatments are being designed for wells in Mann Field with higher current oil productivity.
There are unlimited targets for EEOR applications, not only in Myanmar, but throughout the world. These successful initial EEOR applications in Mann Field will allow for treatment design improvements in future wells.
Test Well Selection
The Mann field EEOR tests were conducted on Well 395, completed in September 1981, and Well 101, completed in March 1976. Both wells experienced periodic paraffin buildup and have produced 433,500 and 1,384,525 cumulative barrels of oil respectively. They both met the the criteria for a modified enzyme application.
The modified enzyme treatment in Well 395 was preceded by a wellbore clean-out procedure to prevent injecting any wellbore contaminants into the perforations. Then, 1 Treatment of modified enzyme concentrate, diluted to 2% in filtered 2% KCl water, were used to treat Well 395. Injection pressure was maintained below the formation frac pressure and the entire 155 ft interval was open during the treatment with no diversion of fluid. The well was shut-in for four days before returning the well to production.
Pre treatment production was 14 bopd and 2 bwpd. Current production is 18 bopd and some 530 incremental barrels have been produced in 13 months following treatment. Figure 6 shows the production history of the well before and after the modified enzyme treatment.
Conclusions
Application of a modified enzyme in Mann field improves oil production.
Modified enzyme solution can effectively be recycled into other wells to enhance production although this is not a recommended practice by manufacturer as it not accurate to measure remaining enzyme in solution.
Treating higher impact wells should result in greater profitability.
Diverting Modified enzyme treatments into more intervals should improve treatments results.
Arresting decline rate after treatment is significant result from this test.
Preliminary tests indicate it is more effective in high water cut well.
Ott, W. K., Nyo, T., Aung, W. N., & Khaing, A. T. (2011, January 1). EEOR Success in Mann Field, Myanmar. Society of Petroleum Engineers. doi:10.2118/144231-MS