由孔隙介质多相渗流力学和连续介质理论可知,当多孔介质的孔隙中同时存在两种不混溶流体时,可以通过3个运动方程、2个渗流连续方程以及相应的物性方程来描述其动力特性。基于此,推导并求解了两种不混溶流体饱和多孔介质中全频域波动方程。波动方程推导过程不仅考虑了固体骨架、固体颗粒、不同孔隙流体的压缩性及各相物质间的黏性、惯性耦合,还考虑毛管压力、束缚饱和度及残余饱和度的影响,所以该模型具有较广泛的适用性。研究结果表明,由两种不混溶流体饱和的多孔介质中,同时存在3种压缩波和1种剪切波,各种波的速度和衰减特性将随着频率和饱和度的改变而发生急剧变化。另外,还将此模型的计算结果与已有文献中的试验数据和理论结果进行对比。
Based on the mechanics of fluids in porous media and the continuum mechanics, a continuum theory of multiphase porous media is developed to analyze the propagation of elastic waves in a porous medium saturated by a mixture of two immiscible, viscous, compressible fluids. The behavior of porous media can be described by three equations of motion, two continuity equations of flow, and a supplementary equation that describes the constitutive relationships. A closed-form solution is derived for a fully coupled model considering the capillary pressure and irreducible/residual saturation, which demonstrates the existence of three types of compressional waves and one type of shear wave. The theoretical results are plotted and compared with the experimental data available in the previous studies. This solution is highly versatile in that it considers compression of the solid grain, compression of both pore fluids, deformation of the porous skeleton, and spatial damping. In addition, all the material parameters in this model are measurable.