低渗透高温气藏清洁压裂液研究与应用——以吐哈盆地K22气井为例

吐哈盆地K22气井储层埋藏深度3 720 m，地层温度110 ℃，压力系数1.01，具有低孔隙度、低渗透率特性。邻井岩心流动实验为强水敏、强-极强水锁；所在区域平均应力梯度为0.025 7 MPa/m。因此，基于新型表面活性剂研究了一种新型清洁压裂液，并做了有关的测试分析。RS600流变仪评价测试结果表明，该压裂液黏温性能稳定、黏度可达60 mPa·s；采用控制应力流变仪测试的该压裂液弹性模量远大于黏性模量，因而具有优良的黏弹性、流变性和携砂性能；Fann35黏度计测试结果表明，在辅剂作用下易于破胶，对储层伤害小；环路实验装置测试结果表明，该压裂液流动摩阻低。现场应用表明：摩阻仅为清水摩阻的1/3，成功加砂44.1 m³，平均砂比20.6%；施工过程液体性能稳定，压后破胶彻底、返排率达到79.26%；能够满足中等加砂规模的要求。该清洁压裂液成本相对较低且配制简单，有效地解决了在高温气井难以破胶的问题，对低渗透高温气藏压裂改造提供了技术支持。

A case study of clean fracturing fluid applied in the well K22,Turpan-Hami Basin

The pay zone in the K22 gas well, Turpan Hami Basin, is 3720 m deep with the temperature of 110℃ and the pressure coefficient of 1.01, and is of low porosity and low permeability. From the core experimental analysis, the pay zone is found to be strong water sensitive, strong to extremely strong water blocking, and the average pressure gradient there is about 0.0257 MPa/m. Therefore, based on a novel surfactant, a new clean fracturing fluid was developed and relevant tests were carried out. Specifically, its viscosity vs. temperature is stable according to the evaluation of the RS600 rheometer, and the viscosity is up to be 60 mPa·s; its elastic moduli is much larger than loss moduli according to the tests by the stress controlling rheometer, which means excellent visco elastic property, rheological property and proppant carrying capacity; it tends to gel breaking when processed by supplementary additives and does little harm to the formation according to the tests by the Fann35 viscometer; it also shows low flow resistance through tests of the loop equipment. A field application shows that its resistance is only one third of that of water friction and 44.1 m³ proppant has been injected into the formation with an average sand ratio of 20.6%. During fracturing treatment, the liquid shows stable performance and completely broken gel with a flow back rate as high as 79.26%. This satisfies the requirements of the moderate rate sand adding. This low cost, easily prepared clean fracturing fluid effectively solves the problem of difficult gelout in a high temperature gas well effectively. Moreover, it provides technical support for the fracturing in low permeability and high temperature gas reservoirs.