Microbial community in petroleum reservoir and its pressure adaptation mechanisms

Abstract:

Nowadays, most of Chinese oil reservoirs are at the high-moisture later stage. In this case, microbial enhanced oil recovery (MEOR) technology attracts more and more attention in oil industry by its special advantages such as low cost and environmental friendliness. Until now, MEOR has been developed as one of the most affective techniques for petroleum exploitation. High pressure is an important abiotic feature of oil reservoirs which makes an influence on survival and activity of microorganisms in oil reservoirs. In this paper, we reviewed the main features of oil reservoir and its microbial community, the pressure adaptation mechanisms of microorganisms, and the metabolic characteristics of hydrocarbon-degrading microorganisms under high pressure. In details, we introduced the microorganisms resources in oil reservoirs, microbial community structure both in oil and water phases, how microorganisms emulsified petroleum, microbial cooperation patterns in anaerobic environment, microbial community structure was affected by temperature and pressure, as well as a successive of MEOR examples. Further on, detailed discussions were given about the pressure adaptation mechanisms of microorganisms in oil reservoirs, in which cells may modify cell membrane structure, storage lipid composition, and special intracellular enzymes expression to adapt well in the high-pressure environment. Finally, special attention was paid to hydrocarbon-degrading microorganisms grown at high pressure. Our review provides that the metabolic rates of microorganisms were lower at high pressure than that at atmospheric pressure, and piezotolerant and piezophilic microorganisms have significantly different hydrocarbon-degrading rates.