超临界CO2压裂缝内支撑剂运移规律

为了优化超临界CO₂压裂工艺技术和施工参数，考虑超临界CO₂压裂液中支撑剂颗粒之间相互作用，采用欧拉-拉格朗日方法中的多相质点网格方法，建立超临界CO₂压裂缝内支撑剂运移数学模型，通过室内水力压裂支撑剂运移物模实验验证模型准确性，进行超临界CO₂压裂缝内支撑剂运移规律计算和分析。研究表明:未增黏CO₂由于黏度低，携砂效果极差，优化其他参数对携砂效果影响不大；CO₂黏度增加到2.5 mPa·s即可有效提高携砂效果，采用超轻支撑剂与细尺寸颗粒组合，携砂效果与增黏到10 mPa·s效果相差不大；优化支撑剂密度比尺寸对携砂效果提高更为明显；增大排量可以提高携砂效果，但排量继续增大，其携砂效果变化较小；流体滤失对CO₂携砂效果影响变化不大。该研究为解决CO₂携砂性能差的问题提供了技术支撑，对超临界CO₂压裂设计优化及现场施工具有重要指导意义。 

Proppant Migration in Fracture Fractured with Supercritical CO2 Fracturing Fluid

In order to optimize the supercritical CO₂ fracturing technology and construction parameters, considering the interaction between proppant particles in supercritical CO₂ Fracturing Fluid, the multiphase particle grid method in Euler Lagrange method is used to establish the mathematical model of CO₂ fracturing proppant migration. The accuracy of the model is verified by indoor hydraulic fracturing proppant migration model experiment, and the supercritical CO₂ fracturing proppant migration law is calculated and analyzed. Research shows: Due to the low viscosity of non tackifying CO₂, the sand carrying effect is very poor, and the optimization of other parameters has little effect on the sand carrying effect; When the viscosity of CO₂ increases to 2.5 mPa·s, the sand carrying effect can be effectively improved. The combination of ultra-light proppant and fine particles has little difference between the sand carrying effect and the viscosity increasing to 10 mPa·s; Optimizing the density ratio of proppant to size can improve the sand carrying effect more obviously; Increasing the displacement can improve the sand carrying effect, but if the displacement continues to increase, the sand carrying effect changes little; Fluid filtration has little effect on CO₂ sand-carrying effect. This study provides technical support for solving the problem of poor sand carrying performance of CO₂, and has important guiding significance for supercritical CO₂ fracturing design optimization and field construction.