利用分子生物学技术分析生物气藏中甲烷形成途径

Methane production pathway in biogas reservoirs via molecular biological technique

针对松辽盆地阿拉新气田杜6-3井、敖南气田敖-7井地层水样品,以基因组总DNA为模板,用细菌和古茵的引物对16S rDNA基因进行聚合酶切反应扩增、基因转化和测序;基于基因序列信息,构建气藏中微生物细菌、古菌克隆文库,绘制本源微生物细菌、古菌系统发育树,分析微生物群落结构,推测甲烷合成的可能途径。结果表明,杜6-3井和敖-7井样品中微生物种类较少,细菌文库中绝对优势微生物为假单胞菌属微生物,古菌文库中绝对优势微生物为甲烷杆菌属微生物。适宜的条件下,杜6-3井和敖-7井中的微生物菌群均具备利用CO2转化为甲烷的潜力。杜6-3井菌群产甲烷途径推测主要为CO2还原途径,不能完全排除有少量乙酸发酵产甲烷的可能性;敖-7井样品中,甲烷微生物合成途径明确为CO2还原途径。

To investigate the microbes in formation water samples from Well Du 6-3 and Ao-7 in the Alaxin and Aonan gas fields, Songliao Basin, 16S rDNA was amplified using the Polymerase Chain Reaction （PCR） technique with templates from the extracted DNA and primers of bacteria and archaea. The PCR products were also inserted into vectors and then ligated with competent cells for gene sequencing. Based on the obtained gene sequences, bacterial and archaeal libraries were constructed and microbiological phylogeny graphs were obtained for the samples to understand the structure of microbial community and deduce the possible pathways of methanogenesis. The result indicates that there are only a few types of microbes in the samples of the two wells. Pseudornonas and Methanobacterium are the dominant species in the microbial and archaeal libraries, respectively. Methane generation via indigenous microbial metabolism may be ultimately realized using the right method under favourable conditions in the two fields. It is concluded that the indigenous microbial community in Well Du 6-3 mainly generated methane by CO2 reduction, but methanogenesis of acetic acid could not be completely excluded. The methane from Well Ao-7 is shown to have been definitely converted from CO2.