地下固体介质弹性模量反演

Inversion of elastic modulus of underground solid medium

地下固体介质弹性模量是固体地球定量表征的重要参数,是探测地球内部结构、地下流体分布、设计合理工程方案的关键之一.本文首先简要分析常用的流体饱和孔隙介质岩石物理模型,在此基础上通过数值计算,详细讨论了流体饱和多孔介质等效弹性模量对固体基质、孔隙度、孔隙结构和孔隙流体的敏感性,探讨了利用等效介质弹性模量反演固体基质弹性模量的可行性,建立了固体基质弹性模量的非线性方程系统,提出了该方程系统的数值迭代求解方法,并通过对三类岩石样本实验室测量数据的反演和结果分析,验证了方法的有效性.文中同时通过不同条件下对实验数据的反演,探讨了孔隙结构、孔隙流体和等效介质弹性模量对反演效果的影响,为方法的合理有效应用提供依据.

Elastic modulus of underground solid medium is an important parameter for quantitative characterization of the solid earth. It is one of the keys to explore the internal structure of earth and the distribution of underground fluid and to design a reasonable project scheme. In this paper, we analyze the rock physics models commonly used for saturated porous media firstly, and then discuss the sensitivity of the equivalent elastic modulus to solid matrix, porosity, pore structure and pore fluid and feasibility of using the equivalent elastic modulus to inverse the elastic modulus of solid matrix in detail by numerical calculation. Based on these, we establish the nonlinear equation system of the matrix elastic modulus, and a numerical iterative method for solving the equations system is proposed. The inversions of the experimental data from three kinds of rock samples verify the effectiveness of the method. Through inversion of the experimental data under different conditions, we also discuss the influence of pore structure, pore fluid and the equivalent elastic modulus on the inversion, which provides the basis for the reasonable and effective application of the method.