工业氯化钙加重胍胶压裂液体系研究与现场试验

为了解决现有加重压裂液体系成本高及加重密度低等问题，采用工业氯化钙作为加重剂，研发了一种低成本加重压裂液技术。在分析硼交联剂在氯化钙胍胶基液中交联受阻机理的基础上，制备了耐高浓度氯化钙溶液的交联剂，可在低pH值环境下使高浓度氯化钙溶液和胍胶基液形成交联冻胶。工业氯化钙加重胍胶压裂液具有加重密度高、基液黏度低和耐温耐剪切性能良好等特点，在温度140 ℃、剪切速率100 s–1条件下剪切2 h后，冻胶黏度大于100 mPa·s。现场试验表明，超深井采用氯化钙加重胍胶压裂液进行压裂施工，施工压力可降低10～15 MPa。研究表明，氯化钙加重胍胶压裂液性能可靠，能够降低超深高应力储层改造施工压力，提高压裂效果，具有现场推广应用价值。 

Research and Field Tests of Weighted Fracturing Fluids with Industrial Calcium Chloride and Guar Gum

To solve the problem of high cost and low weighting density in existing weighted fracturing fluid systems, a low-cost technology for weighting the fracturing fluid with industrial calcium chloride was developed. After analyzing the blocking mechanism of boron crosslinking agent in calcium chloride and guar gum base solution, a high-concentration calcium chloride-resistant crosslinker solution was developed. It has the advantage of being able to form crosslinked gel at low pH with high-concentration calcium chloride solution and guar gum base fluid. The industrial calcium chloride weighted guar gum fracturing fluid is characterized by its high weighting density, low base fluid viscosity, strong temperature and shear resistance. After the shearing at 140 °C and with a shearing rate of 100 s–1 for two hours, the gel viscosity was greater than 100 mPa·s. Field tests indicated that the operating pressure can be reduced by 10–15 MPa in ultra-deep wells by using the weighted fracturing fluid with calcium chloride and guar gum. The results showed that fracturing fluid has reliable performance, and could reduce the operational pressure in ultra deep and high stress reservoir reconstructions, and thereby improve the fracturing effect, which has the value of field popularization and application.