流体黏度对岩石致裂影响的数值模拟分析

Numerical Simulation Analysis of Fluid Viscosity Influence on Rock Hydraulic Fracturing

为了探究流体黏度对岩石液压致裂过程的影响,在离散元软件中加入流-固耦合算法,对注入不同黏度液体的岩石试件的破裂失稳过程进行模拟并对比分析。结果表明,岩石在2种液体作用下都产生拉伸裂纹和剪切裂纹,而采用低黏度的液体致裂时,拉伸裂纹释放的能量较弱,不易与周围的噪音信号区分;采用高黏度的液体致裂时,拉伸裂纹与剪切裂纹释放的能量均较强,在声发射试验中都能被监测到。

A series of simulations for hydraulic fracturing was performed by using the flow-coupled DEM code to discuss the influence of the different fluid viscosity. The numerical results show although tensile cracks and shear cracks generated in both two simulations, the energy released from a tensile crack becomes small and such a small acoustic emission signal is easily buried in a noise and difficult to be measured in an experiment when using low viscosity fluid. However when using high viscosity fluid, the energy of tensile and shear cracks are strong enough to be monitored in the acoustic emission test.