贝莱斯芽孢杆菌B6强化驱油机制分析及在高矿化度油藏中的应用

Bacillus velezensis B6: mechanism of enhanced oil recovery and application in highly mineralized oil reservoirs

摘要:

【目的】筛选油藏内源功能微生物并探究其驱油机理，现场试验以确定油藏内源微生物提高原油采收技术应用的工艺和技术可行性。【方法】采集英东油田样品，利用原油平板筛选驱油功能菌，评价其环境适应性并优化培养条件，通过乳化性能、降黏防蜡和烃转化能力等评估其驱油性能并探索其潜在机制，并在油田现场进行微生物强化驱油试验。【结果】从油水样品中分离到的贝莱斯芽孢杆菌(Bacillus velezensis) B6，其乳化活性指数(emulsifying activity index, EI24)值为100.00%，降黏率为97.20%，防蜡率为86.90%，表明菌株B6具有良好的乳化降黏性能，具有提高原油采收的潜力，并且能够减少原油中的重质组分而增加轻质烃类，改善原油物性，提升原油品质。进一步在英东油田、跃进油田和花土沟油田进行微生物单井吞吐和清防蜡作业，共进行62井次现场试验，累计增油1 460.36 t，平均延长洗井周期47 d，经济效益为342.50万元，投入产出比为1:4。【结论】通过室内研究和现场试验，证实内源微生物Bacillus velezensisB6具有显著提高原油采收和油井清防蜡的效果，应用潜力巨大。

关键词:微生物吞吐采油;乳化降黏;规模化发酵;微生物清防蜡

Abstract:

[Objective] To screen the indigenous functional microorganisms in reservoirs and explore their oil recovery mechanisms, we conducted field tests to determine the process and technical feasibility of enhancing crude oil recovery by indigenous microorganisms. [Methods] Wecollected samples from the Yingdong Oilfield and used oil plates to screen for the target bacteria. Next, we evaluated the environmental adaptability and optimized the culture conditions of the strain. Further, we measured the emulsifying, viscosity-reducing, paraffin-resistant, and hydrocarbon conversion abilities of the isolate to evaluate the oil recovery competence of the strain and explored its oil recovery mechanism. Finally, we carried out the microbial enhanced oil recovery tests in the oilfields. [Results] We isolated Bacillus velezensis B6 from the oil-water sample with an emulsifying activity index (EI24) of 100.00%, a viscosity reduction rate of 97.20%, and a paraffin resistance rate of 86.90%, which indicated that strain B6 had good emulsifying and viscosity-reducing abilities and improved oil recovery potential. Strain B6 could reduce heavy components in crude oil and increase light hydrocarbons to improve crude oil properties and quality. Moreover, we carried out single-well huff and puff and paraffin removal operations in Yingdong Oilfield, Yuejin Oilfield, and Huatugou Oilfield with a total of 62 well-times in the field test, which resulted in a cumulative oil increase of 1 460.36 tons and an average delay of 47 days in the well flushing cycle. The economic benefit was CNY 3.425 million, and the input-output ratio was 1:4. [Conclusion] The laboratory studies and field tests proved that indigenous B. velezensis B6 can significantly improve the oil recovery and well paraffin removal, with great application potential.

Key words:microbial huff and puff;emulsification and viscosity reduction;large-scale fermentation;microbial paraffin removal