基于SPH方法的组合射流破岩模拟研究

Numerical Simulation of Rock Breaking by Combined Jets Based on SPH Method

在利用组合射流开采页岩油气资源的过程中,射流参数的变化对组合射流破岩效果有着较大影响。为揭示参数变化对组合射流破岩能力的影响,利用光滑粒子流体动力学(SPH)方法构建组合射流冲蚀岩石的数值模型,通过模拟组合射流冲击岩体问题,并与已有结果进行对比,验证了所建模型的有效性。在此模型的基础上,研究了不同射流喷距、射流直径和射流轴向倾角下组合射流破岩的动态损伤过程。研究结果表明:随着射流喷距的增大,岩石破损坑纵截面面积先增大后减小,这说明喷距存在最佳值;射流直径的改变会直接影响岩石破损坑的形状,射流直径越大,岩石破损坑纵截面面积越大,破损坑底部的凸台越小;岩石表面破损坑径随着射流轴向倾角的增大而增大,但其纵截面面积变化较小。研究结果可为组合射流在喷射压裂作业中的应用提供理论支撑。

During the exploitation of shale oil/gas resources by combined jets,the change of jet parameters has a great influence on the rock breaking effect of combined jets.In order to reveal such influence,a numerical model of rock breaking by combined jets was established by the smoothed particle hydrodynamics(SPH)method.With this model,the rock breaking by combined jets was simulated,and the results were compared with the existing research results to verify the effectiveness of the established model.Furthermore,the dynamic damage process of rock breaking by combined jets was studied under different jet distances,jet diameters and jet axial inclinations.The results show that with the increase of jet distance,the longitudinal section area of rock damage pit increases and then decreases,suggesting that there is an optimal jet distance;the jet diameter can change the shape of rock damage pit-the larger the jet diameter,the larger the longitudinal section area of the rock damage pit,and the smaller the bump at the bottom of the rock damage pit;the diameter of the pit on the rock surface increases with the increase of the jet axial inclination.The research results can provide a theoretical support for the application of combined jets in jet fracturing.