Abstract: Residual-oil in-situ gasification is a forward-looking technology aiming at abandoned reservoir. Slow gas-producing rate is the main problem at the present stage, unable to satisfy the demand for developing large-scale oilfields. In this study, microbial electrolytic cell was introduced to supply energy for microbial growth and metabolism, realized the "microorganism-electrochemistry" combination effect and accelerated the material and energy supply in the process of microbial gasification, so as to speed up the microbial methane synthesis rate. Firstly, the "syntrophic metabolism-methane production" microflora with high gas-producing rate was obtained by acclimating from oil reservoir, and the microflora community structure was analyzed by high-throughput sequencing. The results show that Syntrophomonas, Syntrophus, Syntrophothermus and other microbes with syntrophic metabolism characteristics become the dominant bacterial genera. Methanoculleus, Methanobacillus and Methanobacterium can use H₂+CO₂ and formate as the substrate to synthesize methane, and then become the dominant archaea genera. Moreover, the gas-producing analysis shows that this microflora methane synthesis rate reaches 5.3×10^-3mL/(cm³·d), then under the same conditions, the microbial electrolytic cell additionally increased by 0.15 V is used to enhance the methane synthesis of such a microflora; the methane synthesis rate is improved to 14.7×10^-3mL/(cm³·d) by 177.4%, and the Faradic efficiency is increased from 64.7% to 123.2%. Finally, the influence factor for the microbial electrolytic cell enhancing methane synthesis rate was studied, and the methane synthesis rate can be impacted by carbon source, mineralization, electrode material and electric potential, of which electric potential can significantly affect the methane synthesis rate. Under the condition of adding 1.5 V electric potential, the methane synthesis rate of such a microflara can reach 33.16×10^-3mL/(cm³·d), increased by 526.4%.

Key words: residual oil gasification, microbial electrolytic cell, methanogen, synthesis rate, high-throughput sequencing

摘要： 残余油原位气化是一项针对废弃油藏的前瞻性技术，现阶段其主要问题是产气速率慢，无法满足大规模油田开发的需求。通过引入微生物电解池为微生物生长代谢提供能量，实现"微生物-电化学"联合作用，加快微生物气化过程中物质与能量供给，从而加快微生物的甲烷合成速率。首先，从油藏中富集驯化获得高产气速率的"互营代谢-产甲烷"菌群，高通量测序分析其菌群群落结构结果显示，Syntrophomonas、Syntrophus和Syntrophothermus等具有互营代谢特点的微生物成为细菌的优势种属；Methanoculleus、Methanobacillus和Methanobacterium等能够以H₂+CO₂和甲酸盐为底物合成甲烷的微生物成为古菌的优势种属。然后，产气分析表明，该菌群的甲烷合成速率达到了5.3×10^-3mL/（cm³·d），在同样条件下，用外加0.15 V的微生物电解池强化该菌群的甲烷合成，甲烷合成速率提高了177.4%，达到了14.7×10^-3mL/（cm³·d），法拉第效率由64.7%提高到123.2%。最后，研究了微生物电解池强化甲烷合成速率的影响因素。碳源、矿化度、电极材料和电势均能够影响甲烷的合成速率，其中电势能显著影响甲烷的合成速率。在外加1.5 V电势的条件下，该菌群的甲烷合成速率达到了33.16×10^-3mL/（cm³·d），甲烷合成速率提高了526.4%。

关键词: 残余油气化, 微生物电解池, 产甲烷菌, 合成速率, 高通量测序