大规模体积压裂过程中压裂液性能表征方法研究

针对SY/T 5107-2016《水基压裂液性能评价方法》压裂液性能评价标准未能模拟大规模体积压裂过程中压裂液剪切历史，尤其缺少过炮眼高速剪切对压裂液性能影响的重要环节，项目开展模拟体积压裂施工全过程压裂液体系性能测试方法探索性研究。参照现场实际施工排量，模拟压裂液流经管柱、炮眼和裂缝不同阶段的剪切历史，同时，以压裂液破胶低伤害为前提进行破胶剂量优化，在此基础上进行压裂液流变性能测试，保证压裂液满足施工过程具备携砂性能和施工结束后一段时间内完全破胶的双重要求；采用透明平行板模型，考察使用条件下压裂液动态携砂性能，测试结果为大规模体积压裂“全裂缝支撑”提供设计依据。新方法测试结果表明，复合交联瓜胶压裂液体系和交联聚合物压裂液体系通过高速炮眼后黏度损失较大；乳液缔合型压裂液体系对破胶剂敏感，在满足破胶低伤害的前提下，动态携砂性能难以满足裂缝远端支撑剂铺置要求；低浓度瓜胶压裂液体系添加优化用量破胶剂，体系在施工排量下动态携砂性能良好，满足裂缝远端支撑剂铺置的技术目标。 

Study on Characterization of the Performance of Fracturing Fluids in Large Scale Volumetric Fracturing

In the national standard “The evaluation measurement for properties of water based fracturing fluid” (SY/T 5107-2016), the shearing history of a fracturing fluid in large scale volumetric fracturing and the high shear rate of the fracturing fluid when it passes through a perforation cannot be simulated. A study has been performed on the investigation of how to measure the performance of a fracturing fluid in the whole process of volumetric fracturing job. Based on the actual flow rates in field fracturing operation, the shear history of a fracturing fluid flowing through pipes, perforation and formation fractures was simulated. Meanwhile, the dosage of gel breaker was optimized in an effort to find the concentration of the gel breaker when the lowest damaging to the reservoir is required. Thus, the evaluation of a fracturing fluid should be able to quantify two parameters; sand carrying capacity of the fracturing fluid which satisfy the needs of fracturing job and thorough breaking of the gel some time after the fracturing job is completed. Using the transparent parallel board model, the dynamic sand carrying capacity of a fracturing fluid was investigated, and the test results will provide a design basis for the “full fracture propping” in large scale volumetric fracturing. The results of the new evaluation method show that the compound crosslinked guar gum fracturing fluid and the crosslinked polymer fracturing fluid have the highest viscosity losses when passing through perforations at high flow velocity. The emulsion association fracturing fluid is sensitive to gel breaker, if the formation damage caused by gel breaking process is low, the dynamic sand carrying performance will not be able to satisfy the needs of placing proppant particles into the distal end in a fracture. A low concentration guar gum fracturing fluid treated with optimized amount of gel breaker will have good dynamic sand carrying capacity at flow rates prevailing in field operations, and thus satisfy the technical goals of placing proppants into the distal end of a fracture.