连续携砂型变黏滑溜水研制与应用

Development and application of variable viscosity slick water for continuous sand carrying

致密油储层大规模体积压裂施工中,针对存在常规滑溜水不能连续加砂、凝胶使用量大、压裂成本高、储层伤害大等问题,开展了连续携砂型变黏滑溜水体系的研制与应用。通过室内合成一种新型降阻剂,结合黏土防膨剂、助排剂的添加剂的优选,研制出一套适合致密油储层大规模体积压裂的低成本、高携砂的变黏滑溜水体系。室内实验结果显示,该体系具有低黏高弹特征,是明显的黏弹性流体, 90℃条件下剪切黏度为22.04mPa·s,弹性模量和黏性模量的比值为42.932,残渣含量低,储层孔喉伤害率为17.99%,具有良好的储层保护性能。体系的降阻率达到77.8%,防膨率为75.41%,界面张力为0.31mN/m,最高动态携砂砂比为40%,综合性能优良,能够满足致密储层大规模体积压裂对速溶、降阻、防膨、低伤害、高携砂的要求。该体系在致密油储层压裂现场进行成功应用,各项施工参数均能达到设计要求,极大地提高体积压裂的效率和改造效果,降低施工成本。

In the large-scale volume fracturing operation of tight oil reservoirs,there were some problems such as conventional slick water could not continuously carry sand,the use of gel was large,the fracturing cost was high and the reservoir damage was large,etc.In order to solve these problems,the development and application of slick water system with variable viscosity that can carry sand continuously were conducted.By synthesizing a new type of resistance reducing agent in laboratory and combined with the optimization of clay anti-swelling agent and drainage-aiding additive,a set of slick water fracturing fluid system with low-cost and high sand-carrying properties and variable viscosity has been developed,which is suitable for large-scale volume fracturing in tight oil reservoir.The results of laboratory experiments show that the system has the characteristics of low viscosity and high elasticity,belonging to an obvious visco-elastic fluid.Under the condition of 90℃,the shear viscosity is 22.04 mPa·s,the ratio of elastic modulus to viscosity modulus is 42.932.The residual content is low,the damage rate of reservoir pore throat is 17.99%,with good protection performance for reservoir.The system has the resistance reduction rate of 77.8%,the anti-swelling prevention rate of 75.41%,the interfacial tension of 0.31 mN/m,and the maximum dynamic sand carrying ratio of 40%.The system has excellent comprehensive performance,which could meet the requirements of large-scale volume fracturing of tight reservoirs for quick dissolution,resistance reduction,antiswelling prevention,low damage and high sand carrying.The system was successfully applied in tight oil reservoir fracturing operation,with all working parameters meeting the design requirements.It has improved the efficiency and stimulation effect of volume fracturing,and reduced the operation cost significantly.