CO_2干法压裂液体系的研究与试验

Research and test on CO_2 dry fracturing fluid system

为提高低压、低渗透、强水锁/水敏伤害致密砂岩储层压后产量，开展了CO2干法压裂液体系的研究。采用分子模拟技术，研究液态CO2与提黏剂分子间微观构型，评价不同CO2提黏剂对液态CO2的提黏效果，优选提黏剂，并建立CO2干法压裂液体系配方。通过研究发现，在62～63℃、15～20 MPa条件下，CO2干法压裂液体系黏度提高至5～10 mPa·s，较超临界CO2的黏度提高240～490倍；对气井岩心渗透率平均损害率为2.75%，对油井岩心渗透率平均损害率为0.98%。该压裂液体系在苏里格气田成功进行了国内第1口CO2干法加砂压裂现场试验，增产效果明显。

In order to increase the production of low pressure, low permeability, strong water locking or water sensitive damaged tight sandstone reservoir after fracturing, research was conducted on CO2dryfracturinglfuidsystem.Themolecularsimulationtech-nique was used to study the microscopic conifguration of molecules between liquid CO2 and viscosiifer, to evaluate the viscosifying effect of various CO2 viscosifer on liquid CO2,tooptimizetheviscosiifers,andtobuildtheformulaforCO2fracturinglfuid.Basedon the research, it was found that, under the conditions of 62–63℃ and 15–20 MPa, the viscosity of CO2dryfracturinglfuidsystemwas increased to 5–10 mPa·s, which is 240–490 times that of supercritical CO2. The average rate of damage to core permeability of gas wells was 2.75%, and the average rate of damage to core permeability of oil wells was 0.98%. This fracturing lfuid system was successfully testedontheifrstdomesticwellwithCO2 dry sand fracturing in Sulige Gas Field, and the production was increased remarkably.