CO2干法压裂液工作效率是改善 CO2压裂流体的携砂性和造缝性的关键，本文以提高纯 CO2流体黏度和降低纯 CO2流体储层滤失系数为目标，采用乳化增黏降滤的技术路线，自主开发出了一种有机硅型 CO2压裂增稠剂（15%表面活性剂 SFA+85%氯代环烷烃与正辛醇的混合溶剂（体积比 1∶1）），建立了 CO2干法压裂液体系（2%~3%增稠剂+97%~ 98%液态 CO2），并研究了该体系的溶解分散性、黏度、滤失量及对岩心的伤害情况。研究结果表明，该体系的黏度比纯 CO2的提高 500~ 1000倍，储层条件下对岩心综合滤失系数比纯 CO2的降低了 87.8%，对储层岩心无伤害。新型 CO2干法压裂液体系在鄂尔多斯盆地成功开展 5口井的现场试验，施工参数和液体效率明显提升，并在国内首次实现了最高砂比 25%，最大单层加砂量 30 m3的施工规模。图 4表 5参 12
The working efficiency of CO2 dry fracturing fluid is the key to improving the sand-carrying and fracture-forming capacities of fracturing fluid. The present study intends to improve the viscosity of pure CO2 fluid and reduce the fluid-loss coefficient of pure CO2 fluid reservoir. A type of organic-silicon CO2 fracturing thickener，composed of 15% surfactant SFA + 85% mixed solvent of hexachlorocyclohexane and n-octanol in volume ratio of 1∶1，was developed based on the technical route of applying emulsification to increase viscosity and reduce filtration. The CO2 dry fracturing fluid system was established，and the optimal recipe was as follows，2% —3% thickener + 97% —98% liquid CO2. The dissolution dispersity，viscosity，fluid loss and damage of the system to the core was investigated. The results showed that the viscosity of the system was improved by 500—1，000 times compared with that of the pure CO2. In the reservoir condition，the comprehensive fluid loss coefficient of the core was reduced by 87.8% compared with that of pure CO2，and no damage was caused to the reservoir core. The proposed CO2 dry fracturing fluid system had been tested in the five wells of Ordos basin. The results indicated that the construction parameters and efficiency of liquid was significantly improved，moreover，it is also the first time in China that a construction project could achieve the highest sand ratio of 25% and the largest single-layer sand injection capacity of 30 m3.