Research On Environmental Microorganisms For Indicating Oil And Gas

MPOG (Microbial Prospection for Oil and Gas) technology was a newtechnology for prospecting oil and gas, which combining the principle ofmicro penetration by the light hydrocarbon and soil microbiogy. It had beenattracted widespread attention in recent years, because it was low cost, shortperiod, high efficiency, good stability and so on.In this paper, the soil samples from three different regions of non-oil andgas reservoir, oil reservoir, and gas reservoir in Haian oilfield of Jiangsu andShengli oilfield of Shandong were taken as research objects. The study,including the methods of detecting soil microorganism number, the methodsof preservating soil sample, the conditions optimizing for microcosm tracerexperiments, methanotrophs for indicating oil and gas based on stableisotope probing, were used some molecular ecology technologies of soilmicrobial DNA extraction, quantitative PCR, DNA-based stable isotopeprobing, molecular cloning and sequece analysis. Main results of this paperwere as follows.(1) Research on the methods of detecting soil microorganism number.The results were indicating that the amount of soil microorganism haddecreased of3%~40%by air-drying; soil DNA yield would be reduced30%~77%by purifying, but the copy number of soil microorganism couldbecome more by quantitative PCR, when the GF-P method was best; it couldbe reduced the impact of DNA analysis by humic acid and other impurities,and improved the amplification efficiency of target microorganisms whichhas reached a higher level in10to100fold dilution that diluting DNAsolution; and it was one of the best ways to maximize the soil microbialbiomass by combining the two methods of purification and dilution.(2) Research on the methods for preserving soil samples of MPOG. Theresults were indicating that the microbial abundance would be reduced byincreasing depth of soil profile; compared with fresh soil, air-drying andlyophilizing would reduce significantly the microbial abundance of different soil profiles, including the copy number of pmoA gene of methane-oxidizingbacteria for indicating oil and gas microbial had decreased90.7%and77.5%,respectively; air-drying could be one of methods of conserving soil samplesfor MPOG, because it had reduced distinctly the microbial abundance, butdidn’t change the trend.(3) Research on the conditions optimizing for microcosm tracerexperiments for indicating oil and gas. The results were indicating that themethane-oxidation of soil was better under10000ppm initial cultureconcentration of methane; the soil profile of30~60cm was used for researchon methanotrophs for indicating oil and gas based on stable isotope probing,because it was not only affected weaker by interference from ground, butmethane-oxidized stronger.(4) Research on methanotrophs for indicating oil and gas based on stableisotope probing. The results were indicating that the clone library ofmethanotrophs for indicating gas and oil had been builted initially. Type Imethanotrophs were the dominant species, accounting for about81%,including approximately67%methanotrophs were similar withMethylobacter and about14%were similar with Methylomicrobium andMethylocaldum; the other methanotrophs were type II, accounting for about19%, all which were similar with Methylocystis. Moreover, naturalgeographical environment may have a certain impact on the research onmicroorganisms for indicating oil and gas.