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地震波传播的物理模拟能够使我们深入了解有关复杂构造、地层和储层特性描述问题。在开发钻探方面,裂缝带的检测和圈定具有极其重要意义。确定一套储层内裂缝的方向在EOR中具有重要作用。AVO研究中的基本原理是提取反射振幅随震源一检波器距离变化的横波信息。本项研究的目标是确定是否可利用三维AVO勘测中的横波信息进行裂缝检测和圈定。 在休斯顿大学的联合地球物理实验室进行了有关模拟的裂缝体系的三维物理模拟实验。裂缝体系由三套各向同性均质层段构成,横向各向同性Phenolite盘嵌入中部层段的中央部位。三个层段是:上部层段为黑色树脂2741LV;中部层段为蓝色Stycast树脂2850MT(包含各向异性盘),及下部层段,Evercoat铸造树脂。在整个模型中进行两次三维地震勘测,第一次采集的测线的方向平行于裂缝方向,第二次采集线与之垂直。在模拟的裂缝系统内也进行了多偏移距和多方位角地震实验。在校正球面发散及震源一检波器方向之后分析了黑色/Stycast树脂界面的反射振幅。 结果表明裂缝化的盘在二次观测中都以较低的AVO梯度为特征。此外,与裂缝方向垂直的勘测获得的三维AVO梯度估计值比测线方向平行于裂缝方向的勘测获得的AVO梯度估计值低30％至40％。沿着不同测线方位的AVO的影响表明在近偏移距处,对于所有
Physical simulation of seismic wave propagation enables us to gain insight into complex structure, formation, and reservoir characterization issues. In the development of drilling, the crack detection and delineation is extremely important. Determining the direction of a set of fractures in a reservoir plays an important role in EOR. The basic principle in the AVO study is to extract the shear-wave information whose reflection amplitude varies with the distance from the source-detector. The goal of this study is to determine whether shear detection and delineation can be done using shear-wave information from 3D AVO surveys. A three-dimensional physical simulation experiment on a simulated fracture system was conducted at the Joint Geophysical Laboratory at the University of Houston. The fracture system consists of three sets of isotropic homogeneous layers, and a transversely isotropic Phenolite disk is embedded in the middle of the middle layer. The three intervals are: 2741LV for the upper layer of black resin; 2850MT for the blue layer of Stycast resin (including the anisotropic disc) for the middle section and Evercoat for the lower section. Three-dimensional seismic surveys are conducted throughout the model. The first acquisition line is oriented parallel to the fracture and the second acquisition line is perpendicular to it. Multi-offset and multi-azimuthal seismic experiments were also performed within the simulated fracture system. The reflection amplitude of the black / Stycast resin interface was analyzed after correcting spherical divergence and source-geophone orientation. The results show that the fractured disk is characterized by a lower AVO gradient in both observations. In addition, the 3D AVO gradient estimates obtained from surveys perpendicular to the fracture direction are 30% to 40% lower than the AVO gradient estimates obtained from surveys whose survey directions are parallel to the fracture direction. The effect of AVO along different alignment directions shows that at near offset, for all