Investigation on Behavior of Bacteria in Resrvoir for Microbial Enhanced Oil Recovery

摘要

Behavior of bacteria activated in reservoir through molasses-injection-tests, was investigated using the restrction fragment length polymorphism analysis with the polymerase chain reaction (PCR-RFLP) method, for elucidating potential bacteia to suppress in situ growth of microbes to be injected into the reservoir in the microbial enhanced oil recovery (MEOR) process. As a result, some bacteria belonging to Enterobacteriaceae species or their close relative species were grown predominantly in the reservoir, among bacteria inhabinting in the ground-water. The foregoing indicates that behavior of these bacteria in reservoir must be taken into consideration when giving a full account of behavior of microbes to be injected into the reservoir to put the MEOR process into operation.Potential proliferation using molasses to activate those bacteria was also estimated on the laboratory tests, to clarify the indispensable conditions for effective and competitive in situ growth of microbes to be injected into the reservoir to operate the MEOR process. In consequence, it became clear that these bacteria have a potential growth exceeding 10~8 CFU/ml, utilizing molasses. These facts indicated that microbes to be injected into the reservoir at the MEOR field tests are necessary to grow more excellently than bacteria inhabiting in the ground-water. In addition, as flow, the injection fluid is influenced by reservoir heterogeneity caused by injection of molasses, it was inferred that microbes to be injected into the reservoir at the MEOR field process are also necessary to grow more remarkably than bacteria inhabiting in the reservoir brine at high permeability zones and bacteria inhabiting in the reservoir rock.