一种新型超分子复合压裂液的性能研究

Performance Evaluation of a Novel Supramolecular Fracturing Fluid

开发出一种新型蠕虫状胶束与缔合聚丙烯酰胺共聚物的超分子结构压裂液体系,研究了耐温耐剪切性、剪切回复性、黏弹性、破胶性、悬砂性以及对支撑剂的导流性能。该复合压裂液(1%黏弹性表面活性剂VES-M+0.15%共聚物VES-G)在100 s-1、90℃下剪切120 min后的黏度为60 m Pa·s,流变性较好。剪切速率从40 s-1增至1000 s-1再恢复到40 s-1,压裂液黏度迅速降低并快速恢复,抗剪切性较好。60℃下的频率扫描结果表明,从0.1rad/s的低频到100 rad/s的高频,压裂液储能模量均大于损耗模量,黏弹性较好。80℃时单颗粒陶粒在不同水配制的压裂液中的沉降速率为0.038数0.054 mm/s,悬砂性较好。加入0.3%氧化类破胶剂30 min后的破胶液黏度为4m Pa·s,表面张力为27.6 m N/m,破胶后残渣为10 mg/L。其导流能力保持率为90%,导流性较好。

The properties of a novel supramolecular complex fracturing fluid consisting of worm-like micelle and associative polyacrylamide copolymer were investigated. The studied properties included rheology,temperature stability,shear recovery,viscoelasticity,gel breaking,sand suspension and fluid conductivity. The results showed that the optimum formula of fracturing fluid was 1% viscoelastic surfactant VES-M and 0.15% copolymer VES-G. The viscosity of fracturing fluid was 60 m Pa·s after shearing 120 min at a shear rate of 100 s-1and 90℃,indicating good rheology. The viscosity of fracturing fluid decreased rapidly with shear rate increasing from 40 s-1to 1000 s-1,and then recovered instantly with shear rate decreasing from 1000 s-1to 40 s-1.The dynamic properties of fluid showed that storage modulus was larger than loss modulus at 60℃ with frequency range 0.1 — 100rad/s,indicating highly viscoelasticity. Gel could be broken with 0.3% oxidative agent in 30 min,the viscosity of fluid after breaking was 4 m Pa·s and the surface tension was 27.6 m N/m,which contained 10 mg/L residue. The static sedimentation rate of proppant in fracturing fluid preparing with different field water was 0.038—0.054 mm/s at 80℃. The retained conductivity of this fluid was 90% which showed good fluid conductivity.