实验室尺度下气水两相裂缝型介质弹性波速度的数值模拟分析

Numerical simulation of elastic wave velocity in gas-water two-phase rock from fractured model

岩心的非均质结构使得采用实验手段研究弹性波速度与岩石力学参数之间的关系时面临较大困难,且超声波测试工作量大,耗资耗时。基于弹性波动理论和Wood孔隙流体模量模型,采用交错网格有限差分方法对气水两相裂缝型介质的弹性波场进行了数值模拟。计算了岩样在不同裂缝分布位置、孔隙度、裂缝产状、裂缝密度和含水饱和度情况下的纵、横波速度及波速比,讨论了这些因素对波速的影响。模拟分析结果表明,该数值模拟计算方法简单、精度高,对利用岩石波速来反演岩石的孔隙结构有一定的指导作用。

Owing to the heterogeneous structure of the core, it is difficult to study the relationship between elastic wave velocity and rock mechanical parameters by means of experiments.And the work of ultrasonic testing is costly and time-consuming.Based on elastic wave theory and Wood pore fluid modulus model, we simulated the elastic wave field in gas-water two-phase rock from fractured model by using staggered grid finite difference method.We also calculated the P-wave velocity, S-wave velocity and wave velocity ratio of the core in the condition of different fracture distribution, porosity, fracture occurrence, fracture density and water saturation.And the effect of these factors on the wave velocity was discussed.The numerical calculation method is simple and its accuracy is high.It has a certain guiding significance in the inversion for rock pore structure by the elastic wave velocity.