滑溜水–胶液一体化压裂液研究与应用

Research and Application of Slick Water and Gel-Liquid Integrated Fracturing Fluids

滑溜水黏度较低,不能满足造缝、携带大粒径支撑剂和高砂比施工要求,限制了非常规储层大型压裂效率的提高。为此,以丙烯酸、丙烯酰胺、2-丙烯酰胺基-2-甲基丙磺酸和单体A为原料,采用反相乳液聚合法合成了一种耐高温、速溶型聚合物降阻剂SFFRE-1。通过研发与降阻剂SFFRE-1配伍性好的高效助排剂和优选黏土稳定剂,形成了滑溜水–胶液一体化压裂液。该压裂液耐温160℃,通过调整降阻剂SFFRE-1的加量,其黏度在1~120 mPa·s可调,在压裂施工过程中能够实现滑溜水和胶液在线混配及即时切换的要求。该压裂液在四川盆地的页岩气井和胜利油田的致密油井进行了应用,压裂过程中压裂液表现出良好的降阻和携砂性能,降阻率最高达到86%,砂比最高达到43%。研究和现场应用表明,滑溜水–胶液一体化压裂液能够满足非常规储层大型压裂施工需求。

Due to its low viscosity, slick water has limited efficacy in inducing fractures, low carrying capacity for large particles, and a low sand concentration that fails to meet the needs for operation, which limits the efficiency of large-scale fracturing in unconventional reservoirs. Therefore, SFFRE-1, a heat resistant friction reducer dissolves instantly with acrylic acid(AA), acrylamide(AM), 2-acrylamide-2-methylpropyl sulfonic acid(AMPS) and Monomer A as raw materials, was developed by inverse emulsion polymerization. A slick water and gel-liquid integrated fracturing fluid was produced by researching and developing an optimal clay stabilizer and an efficient cleanup agent highly compatible with SFFRE-1. The resulting fracturing fluid can resist temperature as high as 160 °C, and its viscosity can be adjusted from 1 to 120 mPa·s by adjusting added amount of SFFRE-1. In this way, on site mixing and real-time transition between the slick water and gel-liquid in fracturing treatments can be achieved. The fracturing fluid has been applied in shale gas wells in Sichuan Basin and tight oil wells in Shengli Oilfield. It has shown excellent performance in friction reduction and sand carrying: the friction reduction rate reached 86% and the sand concentration was boosted to43%. The research and field application show that the slick water and gel-liquid integrated fracturing fluid can meet the requirements of large-scale fracturing in unconventional reservoirs.