油气藏上方土壤中甲烷氧化菌群落结构分析——以沾化凹陷某油气田为例

Analysis of Methane-oxidizing Bacteria Community Structure in the Soil above Oil and Gas Reservoirs——An Oil and Gas Field of Zhanhua Depression as an Example

以胜利油田沾化凹陷某油气田内油区、气区和背景区上方近地表的土壤为例,构建了甲烷氧化菌功能基因(甲烷单加氧酶基因)pmoA的克隆文库,以探讨甲烷氧化菌群落结构与地下油气藏之间的关系.对3个文库155个克隆子测序后进行比较分析,发现Ⅰa型甲烷氧化菌Methylobacter、Methylomonas、Methylomicrobium在油区土壤中所占比例分别为23%、21%和17%,在气区分别为31%、15%和16%,在背景区分别为26%、21%和8%;Ⅰb型甲烷氧化菌Methylococcus和Methylocaldum在3个区的比例分别为29%、31%和19%;Ⅱ型甲烷氧化菌Methylocystis和Methylosinus在油区所占比例为10%,在气区为7%,在背景区为27%.Ⅰa型甲烷氧化菌在各区域分布差别不明显,Ⅰb型甲烷氧化菌Methylococcus和Methylocaldum在油气区的丰度较高,而Ⅱ型甲烷氧化菌Methylocystis和Methylosinus在背景区的丰度远远高于油气区.由此可知,在地质历史时期的持续轻烃供应下,长期的油气微渗漏环境可能会促使微生物群落结构产生差异,Ⅱ型到Ⅰ型甲烷氧化菌缓慢地演替.

In order to explore the relationship between the methane oxidizing bacterial community and the oil and gas reservoir beneath the soil, samples collected from near-surface soil in oil, gas, and reference areas around Zhanhua oil and gas field were investigated by constructing three clone libraries ofpmoA, a functional gene for methane monooxygenase in methane oxidizing bacteria. All together 155 picked clones from the three libraries were phylogenetically analyzed, and the result showed that Methylobacter, Methylomonas, Methylomicrobium associated with the type I a methanotroph represented 23%, 21% and 17% in the oil area, 31%, 15%, 16% in the gas area, and 26%, 21%, 8% in the reference area respectively; Methylococcus and Methylocaldum associated with the type I b methanotroph represented 29%, 31%, 19% in the oil, gas and reference area respectively; Methylocystis and Methylosinus accounted for 10%, 7%, 27% in the oil, gas and reference area respectively. Therefore, the distribution difference of type I a methanotroph in different areas was not significant, but the distribution of type b and type was different in the three different areas. The oil and gas area showed a higher abundance of type [ b methanotroph Methylococcus and Methylocaldum than the reference area, while a lower abundance of type Ⅱ methanotrophs Methylocvstis and Methylosinus. It was thus concluded that the geological history of sustained light hydrocarbon supply and the long-term oil, gas micro-seepage might cause different microbial community structures and gradual succession from type Ⅱto type I in the methanotroph community. Fig 3, Tab 1, Ref31