多尺度随机孔隙介质中声波传播机理及声场特性研究

The acoustics theory for heterogeneous porous media is the physical foundation of acoustic wave exploration and elaborate description for reservoir acoustics with oil or gas, so it has predominant application background and important academic value. Up to now, it has not developed a completely satisfactory acoustic model because of the complexity of porous rocks. The porous media acoustics will connect the strictness of mechanics law with natural chaos of porous media; it needs to consider many uncertain parameters, therefore it will be treated easily when the random medium theory is introduced. This task aims to establish appropriate multi-scale random porous media physical model, consider the multi-scale effect and the inertial coupling between the fluids as well as the fluid and solid. We will design a high-precision technique, and improve upon the acquired PSM-BEM coupling program for heterogeneous media in order that the acoustic wave characteristic parameters of physical model in porous media can be directly connected with the physical property of the given rock or fluid. Then we will quantitatively study the spatial distribution, macroscopical shape character and the spatial change detail of physical property in porous media; investigate the effects on the elastic wave propagation characteristics due to the existence of pore space and the fluids in the pore space.

非均匀多孔隙介质声学理论是声波勘探和油气储层声学精细描述的物理基础，具有很强的应用背景和重要的学术价值。由于多孔隙岩石的复杂性，到目前还没有一个十分令人满意的声学模型。多孔隙介质声学将力学定律的严格性与多孔隙介质的自然无序性结合起来，需要考虑大量的不确定性参数，采用随机介质方法可以较容易的进行处理。本项目旨在建立适当的多尺度随机孔隙介质物理模型，考虑流体之间及流固体之间的惯性耦合以及多尺度方面的影响；发展高精度声场模拟算法，改进现有的非均匀介质中伪谱法-边界元法耦合计算程序，使其能将多孔隙介质物理模型的声波特性参数与其他岩石、流体的物理属性直接联系起来，定量的研究孔隙介质的空间分布、宏观形态特征与物理性质的空间变化细节，分析孔隙的存在以及孔隙中含流体的情况对弹性波传播特性的影响。

非均匀多孔隙介质声学理论是声波勘探和油气储层声学精细描述的物理基础，具有很强的应用背景和重要的学术价值。.我们建立了多尺度随机孔隙介质物理模型，该模型考虑了孔隙和裂缝之间的流体流动以及裂缝尺度的影响。数值结果显示，地震频带内发生了频率相关即频散现象，P波速度的频散和衰减至少在两个数量级的频率范围内都很重要。.我们对流体饱和球孔和椭球孔的等效压缩系数进行了计算。推导了流体饱和孔隙介质的宏观等效弹性模量，讨论了体积模量和杨氏模量随频率和孔隙度的变化规律。对流体饱和孔隙介质的纵横波速度进行了计算。纵横波速度随着频率的增加而增加，在低频和高频都趋于稳定。.我们发展了高精度声场模拟算法，改进了非均匀介质中伪谱法-边界元法耦合计算程序，使其能将裂缝介质模型的微观参数与裂缝岩石的宏观特性直接联系起来；用改进后的边界元程序模拟了裂缝岩石中地震波的传播特性，研究了含裂缝介质的微观参数（如取向、裂缝密度、纵横比、填充物等）在空间分布上的改变对波传播特性的影响。