分子模拟助溶剂在硅氧烷类SC-CO_(2)压裂液中的助溶行为研究  

Study on Solubilization Behavior of Molecular Simulation Cosolvent in Siloxane SC-CO_(2)Fracturing Fluid

作　　者：陈雨飞 吴通 张辉[1] 李军[1,3] 周英操 张更 CHEN Yufei;WU Tong;ZHANG Hui;LI Jun;ZHOU Yingcao;ZHANG Geng(China University of Petroleum-Beijing,Beijing 102249;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500;China University of Petroleum-Beijing at Karamay,Karamay,Xinjiang 834000;CNPC Drilling Engineering Technology Research Institute,Beijing 102249)

机构地区：[1]中国石油大学(北京)石油工程学院,北京102249 [2]西南石油大学油气藏地质与开发国家重点实验室,成都610500 [3]中国石油大学(北京)克拉玛依校区,新疆克拉玛依834000 [4]中石油钻井工程技术研究院,北京102249

出　　处：《钻井液与完井液》2023年第5期670-677,共8页Drilling Fluid & Completion Fluid

基　　金：国家自然基金科学基金资助项目“海相深层油气富集机理与关键工程技术基础研究”(19B6003)。

摘　　要：超临界二氧化碳压裂液体系由于黏度低,一般选用加入增稠剂的方法来克服携砂效率低的难题。硅氧烷类增稠剂具有低内聚能和良好的增黏性被广泛地选用,但是使用时需要添加助溶剂提高溶解效果。因此,选用被广泛使用的聚二甲基硅氧烷(PDMS)作为研究对象,利用分子模拟研究了甲醇、甲苯和环己烷等助溶剂的加入对聚二甲基硅氧烷在SC-CO_(2)体系中溶解行为的影响。基于溶剂-溶剂和溶剂-溶质的结合能、径向分布函数和内聚能密度等参数,对比分析了极性助溶剂和非极性助溶剂对聚二甲基硅氧烷在超临界二氧化碳压裂液体系中的助溶效果。分子模拟结果表明,在相同助溶剂含量下,甲醇与溶剂体系溶解度参数差值小于0.5,助溶效果优于甲苯和环己烷。结论分析认为,使用助溶剂提高PDMS在SC-CO_(2)中溶解度的实质是CO_(2)与PDMS聚合物分子间作用力、CO_(2)与助溶剂分子间作用力以及PDMS聚合物与助溶剂分子间作用力的平衡。因此,当硅氧烷类增稠剂本身为非极性材料时,推荐采用甲苯作为助溶剂。若硅氧烷类材料具有一定弱极性时,采用甲醇最为适合。Due to the low viscosity of supercritical carbon dioxide fracturing fluid system,the method of adding tackifier is generally used to overcome the problem of low sand carrying efficiency.Siloxane tackifiers are widely used due to their low cohesive energy and good tackifying effect,but it is necessary to add cosolvent to improve the dissolution effect.Therefore,in this paper,the widely used polydimethylsiloxane was selected as the research object,and the effect of the addition of cosolvents such as methanol,toluene and cyclohexane on the dissolution behavior of polydimethylsiloxane in SC-CO_(2)system was studied by molecular simulation.Based on the binding energy,cohesive energy density and radial distribution function of solvent-solvent and solvent-solute,the solubilization effect of polar cosolvent and non-polar cosolvent on polydimethylsiloxane in supercritical carbon dioxide fracturing fluid system was compared and analyzed.The molecular simulation results show that the solubility parameter difference between methanol and solvent system is less than 0.5 at the same cosolvent content,and the solubilization effect is better than that of toluene and cyclohexane.The conclusion is that the essence of using cosolvent to improve the solubility of PDMS in SC-CO_(2)is the balance of the intermolecular force between CO_(2)and PDMS polymer,the intermolecular force between CO_(2)and cosolvent,and the intermolecular force between PDMS polymer and cosolvent.Therefore,when the siloxane tackifier itself is a non-polar material,toluene is recommended as a cosolvent.When the siloxane material has a certain weak polarity,methanol is the most suitable.

关 键 词：超临界CO_(2)压裂液 PDMS 分子模拟 溶解性 黏度 

分 类 号：TE357.12[石油与天然气工程—油气田开发工程]