A porous medium is composed of a rock skeleton and pore fluids, and seismic wave propagation in it will produce complex and diverse variations influenced by pores and fluids filling. It is very important to carry out the study of closed-form expressions of the plane-wave reflection and transmission coefficients at a planar interface between porous media for analyzing the properties of pores and its fluids and eventually revealing underground oil-bearing reservoirs. In this paper, based on the relationships among seismic wave functions, displacements and stresses in porous media, an exact equation of plane-wave reflection and transmission coefficients with a normal incident fast P-wave is first derived. Considering the characteristics of the parameters in a coefficient matrix of an exact equation, the closed-form expressions with clear geophysical meaning are further derived, which include three parts, the rock skeleton term, the fluid–solid coupling term and the pore fluid term. Through the establishment of two porous media models, the influence of each term in the approximate expression on the reflection characteristics of a fast P-wave is analyzed. Different approximate expressions of the reflection coefficient of a fast P-wave can be selected for oil and gas prediction of different reservoirs, which lays a foundation for the identification of gas, oil and brine.

中文翻译：

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具有法向入射快速 P 波的多孔介质平面界面处平面波反射和透射系数的闭式表达式

多孔介质由岩石骨架和孔隙流体组成，地震波在其中的传播会受到孔隙和流体充填的影响，产生复杂多样的变化。开展多孔介质平面界面平面波反射和透射系数的闭式表达式研究，对于分析孔隙及其流体的性质，最终揭示地下含油储层具有重要意义。在本文中，基于地震波函数、位移和多孔介质中应力之间的关系，首次推导出平面波反射和透射系数与法向入射快速P波的精确方程。考虑一个精确方程的系数矩阵中参数的特性，进一步推导出具有明确地球物理意义的闭式表达式，包括岩石骨架项、流固耦合项和孔隙流体项三部分。通过建立两个多孔介质模型，分析了近似表达式中每一项对快纵波反射特性的影响。不同储层的油气预测可选择不同的快纵波反射系数近似表达式，为气、油、卤水的识别奠定基础。分析了近似表达式中各项对快速纵波反射特性的影响。不同储层的油气预测可选择不同的快纵波反射系数近似表达式，为气、油、卤水的识别奠定基础。分析了近似表达式中各项对快速纵波反射特性的影响。不同储层的油气预测可选择不同的快纵波反射系数近似表达式，为气、油、卤水的识别奠定基础。