Methanogenic Properties And Community Succession Of Petroleum Hydrocarbon Degradation By Indigenous Bacteria

At present, in the oilfield of our country, the prominent issue is crude oilremaining, and this can not be solved by existing technologies. The oil in thedepleted reservoir, with high water reservoirs and low permeability reservoirconvert to methane has attracted increasing attentions. Methane wasmore-accessible fuels than crude oil, which was produced by microbial growthand metabolism, and oil recovery would be raised obviously.In this study, bacteria resource was oil well produced water at differentblocks of Daqing Oilfield, the sole microbial carbon source was crude oil.Methane was detected after2months of culture at a closed medium under45℃.By microbial metabolism,3～15mL cumulative gas was obtained which wasconverted by5g oil in6months.The results showed that, the viscosity crude oil samples decreasedsignificantly compared with before, which has better emulsification effects. Theoil sample of bacteria source of mixture bacteria and bacterial strain N2-D2-139,the viscosity of crude oil has decreased to30mPa.s from50mPa.s at begin. Thiscould prove that the fluid properties of crude oil have been changed, liquiditywas better than before. The emulsification effects that produced bymicroorganism metabolizing hydrocarbons has good values of economic andscientific research. By fermented liquid surface tension analysis, the resultsshowed that surface tension of each samples has about10mNm^-1 decreased, themost obvious one decreased to41mNm^-1from63mNm^-1. And this ability has alasting effect, the surface tension has a good decreasing trend with theincubation time growth. In this experiment, fatty acids in fermentation liquidhave been extracted and separated, it can be seen that fatty acids have two formsin fermentation liquid, the first major includes acetate and propionate, thesecond were low carbon chain fatty acid which between C₂～C₉.Through the method of constructing16S rRNA gene clone library ofbacteria,45C reservoir fluid production strains and the composition anddynamic changes in the process of training are analyzed. After culture capableof degrading crude oil components of bacteria become the dominant bacteria, alot of polar oxygen compounds. Provide substrate for methanogenesis finaloxidation of crude oil. The flora from the initial amount of Hydrogenotrophicmethanogens main into to Hydrogenotrophic methanogens and acetic acidnutrition methanogens the common flora. Archaea detected mainly methanemicro fungi, Methanobacterium classes and a small amount of Crenarchaeota i n archaea. The methane micro fungi methane eight stacks of coccus, methanecapsule bacteria and methane rope sp. group. Can use H₂/CO₂, formic acid andacetic acid producing methane.The flora can be divided into three categories according to the metabolicfunction, which include hydrocarbon degradation bacteria, acetic acid bacteriaand methane-producing bacteria, and these three categories completed theprocess of methane-producing by crude oil. And the screened MethanogenicArchaea were identified as Methanoculleus and Methanosaeta thermophila. Thisgroup of Archaea has good application value because them came from anaerobicmethanogenic culture of crude oil.