可在线施工的反相微乳液聚合物压裂液

An Online Operable Fracturing Fluid Treated with Reverse Microemulsion Polymer

为了使微乳液/反相微乳液聚合物能够配制用于加砂压裂的凝胶压裂液,以丙烯酸、丙烯酰胺、强亲水单体、2-丙烯酰胺基-2-甲基丙磺酸、甲基丙烯酸甲酯、乙烯基磺酸钠等为主要聚合单体,以复合脂肪醇聚氧乙烯醚和环己烷为连续相,反应制备了反相微乳液聚合物——速溶乳液稠化剂BCG-2,其可采用清水和高矿化度盐水配液,配套研发了延缓型弱交联剂,优选了功能助剂,形成了滑溜水压裂液和弱凝胶压裂液配方。利用连续油管测试,该滑溜水压裂液在600 L/min排量下降阻率可达70.9%,并随排量的增大而增大;弱凝胶压裂液受高剪切速率的影响小,并且在150℃、170 s^(-1)下剪切120 min后黏度保持在80 mPa·s以上;压裂液彻底破胶后呈半透明,无沉淀,表面张力为23.87 mN/m,并且几乎无残渣(3 mg/L以下);破胶液与延长油田某井原油在4 h内破乳率可达100%。在延长油田某井利用地层返排液在线配制120℃的弱凝胶压裂液并进行了实验性压裂施工,解决了现场压裂存在的诸多难题,对促进压裂改造向简单、高效、重复利用等方向发展具有重大意义。

To use microemulsion/reverse microemulsion polymers in preparing gel fracturing fluids with sands,an instant emulsion thickening agent BCG-2has been developed through reverse microemulsion polymerization,with acrylic acid,acrylamide,s仕ong hydrophilic monomers,2-acrylamido-2-methylpropane sulfonic acid(AMPS),methyl methacrylate,ethylene,sodium salt of vinyl sulfonate etc.as the monomers,and aliphatic alcohol polyethoxylate and cyclohexane compound as the external phase.BCG-2 is soluble in both fresh water and high salinity saltwater.A slick water fracturing fluid and a weak gel fracturing fluid were formulated with a retarded weak crosslinking agent and selected functional agents.In well testing with coiled tubing,the rate of friction reduction of the slick water at a flowrate of 600L/min was 70.9%,and was increasing with the increase of the flowrate.The weak gel jfracturing fluid,after shearing for 120 min at 150℃,and 170s^-1,still had viscosity of at least 80mPa·s,indicating that the weak gel fracturing fluid is less affected by high shearing rate.The fracturing fluids,after thorough gel breaking,become semitransparent and have no precipitate and almost no residue(<3mg/L).The surface tension of the gel-breaking fracturing fluids is 23.87mN/m.The mixture of the gel-breaking fracturing fluids and a crude oil sample from a well in Yanchang oilfield can be completely demulsified in 4 hours.In a field experiment,a well in Yanchang oilfield was fractured with an online prepared fracturing fluid of 120℃.The experimental operation has solved many problems encountered in field fracturing operations in the past,and is of significance in promoting fracturing operations toward the direction of simplicity,high efficiency and recyclability.