内源微生物驱油及其对油藏微生物活动的影响

Indigenous microbial flooding and its influence on microbial activities in reservoirs

摘要:

【目的】新疆油田六中区为典型水驱普通稠油油藏，水驱效果较差，油藏具有丰富的内源微生物，本研究通过分析内源微生物驱油对油藏微生物活动的影响，确定内源微生物驱油技术在该类油藏的应用潜力。【方法】采用高通量测序及分析化学技术，系统研究实施内源微生物驱油技术后油藏细菌群落结构组成、细菌总数和功能菌群的浓度以及采出液的流体性质，总结内源微生物驱油对油藏微生物活动的影响。【结果】现场试验注入激活剂和空气后，内源微生物被显著激活，细菌群落结构发生明显变化，细菌总数及功能菌群浓度普遍提高了2-3个数量级；各种内源微生物代谢活动显著增强，与地层流体相互作用后，原油明显被乳化，最终石油采收率提高5.2%。【结论】对于内源微生物较为丰富的水驱普通稠油油藏，内源微生物驱油技术对油藏微生物活动的影响显著，具有显著的技术优势和较大的应用潜力，微生物群落结构、功能菌群浓度及其相关代谢产物可以作为评价内源微生物驱油现场激活效果的重要指标，为其他内源微生物驱油现场试验提供技术参考。

关键词:内源微生物驱油;油藏微生物;激活;微生物活动;提高采收率

Abstract:

[Objective] The Liuzhong area of Xinjiang Oilfield is a typical ordinary heavy oil reservoir with poor water flooding effect and rich indigenous microorganisms. We studied the application potential of indigenous microbial flooding in this reservoir by analyzing the impact of indigenous microbial flooding on the microbial activities in the reservoir. [Methods] During the implementation of indigenous microbial flooding, we employed high-throughput sequencing and the techniques of analytical chemistry to systematically determine the microbial community structure, total bacterial count, number of functional microorganisms, and properties of the produced fluid. [Results] The injection of the activator and air into the reservoir in the field test significantly activated the indigenous microorganisms, changed the bacterial community structure, and increased the number of total bacteria and functional bacteria by 2-3 orders of magnitude. Moreover, it significantly enhanced the metabolic activities of indigenous microorganisms. After interaction with formation fluid, the crude oil was obviously emulsified, and the oil recovery was finally improved by 5.2%. [Conclusion] Indigenous microbial flooding significantly affects the microbial activities in the water drive ordinary heavy oil reservoirs with abundant indigenous microorganisms, demonstrating significant technical advantages and great application potential. The microbial community structure, number of functional microorganisms, and concentrations of related metabolites can be used as indicators to evaluate the on-site activation effect of indigenous microbial flooding. The findings of this study provide technical reference for other on-site experiments of indigenous microbial flooding.

Key words:indigenous microbial flooding;reservoir microorganism;activation;microbial activity;enhanced oil recovery