裂隙型单斜介质中多方位地面三分量记录模拟

Multi-azimuth three-component surface seismic modeling for cracked monoclinic media

针对裂隙型储集层中更具代表性的各向异性介质模型,即在各向同性背景介质中含有两组斜交的垂直裂隙所构成的单斜各向异性介质模型,利用时间和空间上可达任意阶的高阶交错网格有限差分技术,对具有不同裂隙填充物性质的单斜介质中波的传播快照进行了模拟.结果证实各向异性介质中波的传播速度随传播方向的不同而产生明显的差异;裂隙填充物的性质对于速度各向异性具有很大的影响.另外,利用坐标旋转法,对水平层状各向异性介质中多方位地面三分量记录进行了模拟,结果表明了方位各向异性介质中,波的传播速度不仅随入射角的变化而变化,同时也随观测方位的不同而产生差异.数值模拟结果为进一步利用地面多方位地震属性进行各向异性参数的反演及裂隙参数的描述提供理论基础.

The snapshots of seismic wave propagation in monoclinic media are modeled using high-order staggered-grid finite difference method. The monoclinic media is a typical anisotropic model in fractured reservoir containing two sets of non-orthogonal vertical cracks in isotropic background and with different fracture infill. The modeling results show that the velocities of wave propagation are significantly different in different directions, and the property of the fracture infill has a large effect on velocity anisotropy. Then the axis rotation method is used in the modeling of multi-azimuth three-component surface seismic survey for layered monoclinic media. The results illustrate that seismic velocities vary not only with the incidence angle, but also with the azimuthal angle. The numerical modeling results can provide theoretical basis for the inversion of anisotropic parameters and also the fracture parameters with the surface multi-azimuth seismic attributes.