油气微生物勘探机理及应用

【目的】微生物油气勘探技术是基于油气藏的轻烃微渗漏原理衍生的地表勘探技术。油气藏中的轻烃部分(C1-C5)以微渗漏的方式通过上覆的沉积层,在近地表土壤中诱导专门利用轻烃的微生物繁殖与生长,油气区的微生物种类与浓度有别于下伏没有油气藏的地区。通过分析微生物的浓度异常特征,对油气富集区及油气藏进行研究和预测。【方法】在人工模拟条件下研究油气微生物数量和群落异常特征,在此基础上,以海相碳酸盐岩气田普光气田为研究对象,进一步开展微生物勘探研究,鉴定油气藏上方气态烃氧化过程的微生物驱动者,提取土壤中的微生物异常信息。【结果】人工模拟条件下发现Lacibacter cauensis、Methylococcaceae、Methylophilaceae与甲烷气体培养正相关(气指示菌),而未培养的硫氧化微生物等则与丁烷培养正相关(油指示菌)。【结论】进一步在普光气田原位研究中进行验证,发现地表油气微生物数量和群落异常与油气藏有较好的关联性;与油气化探指标对比后发现,油气藏上方微生物正异常和轻烃负异常具有较为明显的互补关系。本研究深化了对典型油气藏上方气态烃氧化微生物转化机制的认识,为油气微生物勘探技术提供理论与实践依据。

Research and application of microbial exploration for oil and gas

Objective] Microbial prospecting for hydrocarbons is based on the hydrocarbon microseepage, the natural phenomenon that hydrocarbon gases of subsurface petroleum accumulations migrate upward by reservoir pressure. The detection of the activity and distribution of these highly specialized populations can be used to forecast the existence of oil and gas deposits. However, the hydrocarbon-oxidizing bacterial population is usually not predominant in soil samples above the typical onshore oil and gas reservoirs. It is hard to assess the abundance, distribution, and community composition of the hydrocarbon-oxidizing bacteria, neither to assess the functional activity and distribution of different groups. Methods] In this study, the hydrocarbon-oxidizing bacteria will be studied under simulated environment. Furthermore, hydrocarbon-oxidizing bacteria above the typical onshore oil and gas reservoirs in Puguang gas field, were studied. Results] A coincidence existed between elevated CH4 oxidation activity and the methanotrophic community structure with Lacibacter cauensis, Methylococcaceae, and Methylophilaceae, whereas unculture sulfur oxidizing bacteria had a coincidence with butane oxidation activity. Analysis of the biotechnology profile data for hydrocarbon-oxidizing bacteria was used to extend genetic information for the bacteria and to contribute to a comprehensive understanding of the molecular mechanisms involved in specific biological processes above the typical onshore oil and gas reservoirs. Conclusion] The profiling data of hydrocarbon-oxidizing bacteria will provide a comprehensive insight at different areas of onshore oil and gas reservoirs and lay the foundation for the study of optimizing the technology of microbial prospecting at the biotechnology level.