顺北典型油气藏上方土壤甲烷氧化菌菌群特征及其勘探意义

Characteristics and exploration significance of soil methane oxidation bacteria above typical oil and gas reservoirs in Shunbei

摘要:

[目的] 甲烷氧化细菌（MOB）长期以来一直被用作石油和天然气勘探的重要油气指示菌，其仅能利用甲烷作为唯一碳源。根据甲烷氧化菌菌群特征结合地质剖面可以较好地预测深部油气藏，为石油勘探提供良好的数据支撑。由于传统平板培养法只能针对可培养甲烷氧化菌，方法具有一定局限性。[方法] 本文采用分子生物学技术结合地球化学烃类指标研究了顺北典型油气藏上方土壤中甲烷氧化菌的分布。[结果] 研究结果显示，油气田上方pmoA基因拷贝数与酸解烃含量具有一定的正相关性，且油气区比背景区高0.5-2个数量级。16S rRNA基因高通量测序和pmoA基因的克隆文库结果显示顺北油藏上方土壤中甲烷氧化菌主要以I型为主，水平剖面中甲烷氧化菌随着离油田距离增加存在I型向II型演变的现象，且Methylomonas sp.在背景区与油气区的丰度有较大差异，具有良好的油气指示潜力。[结论] 综上所述，长期微渗透过程中甲烷氧化菌（MOB）的菌群特征对预测深层油藏具有一定的指示作用，结合地质剖面和地表烃类可以有效预测有利油藏区域。

Abstract:

[Objective] Methane oxidizing bacteria are important indicators for oil and gas exploration. For example, characteristics of methane-oxidizing bacteria can be used to predict deep oil and gas reservoir. [Methods] We studied the distribution of methane-oxidizing bacteria above typical reservoirs in Shunbei by using molecular biology techniques combined with geochemical hydrocarbon indices. [Results] The copy number of pmoA gene above the oil and gas field was positively correlated with the content of acid-hydrolyzed hydrocarbon, and the oil and gas region was 0.5-2 orders of magnitude higher than the background region. The results of high-throughput sequencing of 16S rRNA gene and cloning library of pmoA gene showed that the oil reservoir was mainly type I methane oxidizing bacteria in Shunbei, as the distance from the oil field increases, the type I to type II phenomenon of methane oxidizing bacteria exists. The abundance of Methylomonas sp. was quite different in the background area and the oil and gas area. [Conclusion] The characteristics of methane oxidizing bacteria during long-term micro-osmosis of hydrocarbons have certain indications for predicting deep reservoirs, Combining geological profiles and surface hydrocarbons can effectively predict favorable reservoir areas.