Abstract
In MEOR field operations, injection of microorganism (s) may cause the competition between the injected microorganism and natural microorganisms in the reservoir, which may lead to unexpected results. Therefore, utilization of natural microorganisms in the reservoir for MEOR may be one of the best solution.
In the present study, first of all, natural microorganisms were collected from the reservoir brine of six production wells in the target oil field, and 32 bacteria were isolated. Then, their function for MEOR were tested, and it was found that No. 12 strain produced a large amount of CO2 gas and metabolites of ethanol and acetic acid, and addition of a small amount of (NH4)2HPO4 increased the production of CO2.
Huff and Puff field trials with No. 12 strain Jilin oil field, China were carried out for four wells in 1997. As a result, it was found that the oil production rate increased by 46.4% on the average of four wells for 70 day production, due to the increase of rate of production fluid, not the increase of oil cut.
