深层油藏堵水用新型可膨胀改性石墨

Novel expandable modified graphite for water plugging in deep oil reservoirs

关键词:  深层油藏  可膨胀改性石墨  水驱窜流  堵水体系  合成配方优化

Key words:  deep oil reservoir  expandable modified graphite  water flooding channeling  water plugging system  optimization of synthetic formula

摘要:

目的 为了解决深层油藏在注水采油过程中因地质条件复杂、油藏条件苛刻而容易出现的水窜现象，进而导致的采收率下降问题，特别是考虑到现有调堵剂无法适应深层油藏的高温和高盐等苛刻条件，研制了一种可膨胀改性石墨深层油藏堵水体系。方法 以天然鳞片石墨为基材，通过超声协调氧化多元复合插层的方法制备了一种新型的可膨胀改性石墨用于深层油藏封窜堵水；通过正交实验确定了最佳合成配方及最佳合成条件，合成配方为m（天然鳞片石墨）∶m（高锰酸钾）∶m（浓硝酸）∶m（高氯酸）∶m（冰乙酸）∶m（膨胀剂）合成配比=1.0∶0.2∶2.0∶4.0∶2.0∶0.2；优化合成条件为氧化反应时间60 min，反应温度30 ℃；强化插层反应时间30 min，反应温度30 ℃。通过红外光谱、X射线衍射等方法对所合成的可膨胀石墨进行了结构表征。结果 红外光谱、X射线衍射及扫描电镜结果表明所合成的可膨胀改性石墨为预期结构，所用插层剂均成功插入石墨层间，并且膨胀后的石墨颗粒仍保留片状结构。天然鳞片石墨的初始粒径为300 μm，在200 ℃的湿相环境下可膨胀6.0倍，具备良好的膨胀性能。结论 所合成的可膨胀石墨在裂缝中可以充分膨胀，并与粗糙的壁面牢固结合，对窜流通道进行有效封堵，封堵率达到96%，研究成果可为深层油藏储层调控提供新思路。

Abstract:

Objective The aim is to solve the problem of water channeling which is easy to occur due to complex geological conditions and harsh reservoir conditions in the process of water injection and oil recovery in deep reservoirs, and then lead to the decline of recovery rate. In particular, considering that the existing plugging agents cannot adapt to the harsh conditions such as high temperature and high salt in deep oil reservoirs, a water plugging system for deep reservoirs with expandable modified graphite was developed. Method Using natural flake graphite as the base material, a new type of expandable modified graphite was prepared by ultrasonic coordinated oxidation multi-component composite intercalation method for channeling and water plugging in deep reservoirs; the optimal synthetic formula and conditions were determined by an orthogonal experiment. The synthetic formula was that the mass ratio of natural flake graphite, potassium permanganate, concentrated nitric acid, perchloric acid, glacial acetic acid and expander in turn, was 1.0∶0.2∶2.0∶4.0∶2.0∶0.2; the optimal synthesis conditions were oxidation reaction time of 60 min, reaction temperature of 30 ℃; enhanced intercalation reaction time of 30 min, reaction temperature of 30 ℃. The structure of the synthesized expandable graphite was characterized by IR and X-ray diffraction. Result The results of IR, X-ray diffraction and scanning electron microscopy showed that the synthesized expandable modified graphite was the expected structure, and the intercalation agent was successfully inserted between the graphite layers, and the expanded graphite particles still retained the sheet structure. The initial particle size of natural flake graphite used in this study is 300 μm. It can expand 6.0 times in the wet phase environment at 200 ℃, and has good expansion performance. Conclusion The synthesized expandable graphite can be fully expanded in fractures and firmly combined with the rough wall, which can effectively plug the channeling channel, and the plugging rate reaches 96%. The research results can provide new ideas for the regulation of deep oil reservoirs.