Understanding the fluid dependence of the poroelastic stiffness constants of a layered porous package is of great importance in subsurface exploration and development. While the effects of the pore-fluid distribution caused by coarse-scale heterogeneities within an isotropic medium have been studied for several decades, the role of these heterogeneities on the poroelastic constants of a finely layered package is still largely unexplored. In this study, we apply the poroelastic upscaling methods to estimate the fluid-dependent poroelastic stiffness constants of a layered package at the coarse scale. The numerical results show that the refined Gassmann's fluid substitution formulae presented in this paper is applicable if a single fluid phase is uniformly saturated within a layered package. The stiffness constants (⁠|${c_{11}}$| and |${c_{33}}$|⁠) of the layered package with patchy saturations are always higher than or equal to those obtained for the medium with homogeneous saturations, the stiffness constants predicted by the refined fluid substitution formulae for the package simultaneously saturated with different fluids fall between them. Experimental results confirm the relationship between the undrained vertical stiffness constant and the effective pore-fluid bulk modulus for the patch saturated package, indicating that a reasonable result can be achieved by properly choosing an effective poroelastic model that accounts both for the fluid hydraulic communication and the anisotropy of the medium. The results improve the understanding of the coarse-scale fluid dependence of the poroelastic stiffness constants of a layered package, and therefore, it can be used to interpret the seismically inverted elastic parameter for the petrophysical properties in heterogeneous reservoirs.

中文翻译：

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流体饱和度对层状介质不排水孔隙弹性常数的影响

在地下勘探和开发中，了解层状多孔包装的孔隙弹性刚度常数的流体依赖性非常重要。尽管已经研究了各向同性介质中由粗糙尺度的异质性引起的孔隙流体分布的影响，但数十年来，这些异质性对精细层状包装的孔隙弹性常数的作用仍未得到充分研究。在这项研究中，我们应用孔隙弹性放大方法来估计分层包装在粗尺度下与流体有关的孔隙弹性刚度常数。数值结果表明，如果单个流体相在分层包装中均匀饱和，则本文中提出的精细的Gassmann流体替代公式适用。刚度常数（⁠| $ {c_ {11}} $ | 和| $ {c_ {33}} $ |⁠）（具有不饱和饱和度的分层包装）始终大于或等于具有均相饱和度的介质所获得的饱和度，由精化流体替代公式同时对不同流体饱和的包装所预测的刚度常数落在它们之间。实验结果证实了不排水垂直刚度常数和用于补丁饱和包的有效孔隙流体体积弹性模量之间的关系，这表明在合理的结果可以通过适当地选择该占既用于流体液压连通和有效的多孔弹性模型来实现介质的各向异性。结果提高了对分层包装的多孔弹性刚度常数对粗尺度流体依赖性的理解，因此，