济阳坳陷罗家地区各向异性页岩储层全波场地震响应模拟及分析

济阳坳陷罗家地区页岩储层的固有各向异性及水平层理发育使得储层呈现VTI（vertical transversely isotropy）各向异性，而VTI各向异性背景下垂直裂缝的发育使得储层进一步呈现等效正交各向异性特征。本文以正交各向异性介质作为罗家页岩油储层模型，在岩石物理建模中应用Backus平均理论将测井尺度的VTI各向异性粗化至地震尺度，并利用Schoenberg理论在VTI各向异性背景中引入垂直裂缝，进而得到正交各向异性等效介质模型，同时考虑裂缝尺度和流体填充等因素。之后，应用各向异性反射率法进行全波场地震正演模拟，计算正交各向异性页岩油储层AVAZ（amplitude versus azimuth）响应，通过振幅的方位特征进行储层裂缝识别。计算结果表明，PP波、PSV波和PSH波方位振幅响应各不相同，且方位振幅分布图的拟合形状可反映裂缝的发育方向，为页岩油储层中裂缝的地震识别提供依据。

Full Wave Field Seismic Response Simulation and Analysis of Anisotropic Shale Reservoir in Luojia Area of Jiyang Depression

The intrinsic anisotropy and horizontal bedding in the shale reservoir in Luojia area of Jiyang depression results in the reservoir VTI(vertical transverse isotropy)anisotropy; while the existence of the vertical fractures in the VTI anisotropic background makes the reservoir orthorhombic. We took the orthorhombic medium as the model of the Luojia shale reservoir, and applied Backus averaging method to the VTI anisotropic well data in modeling in order to upscale the well data to the seismic scale. Further, by using Schoenberg's theory we introduced the vertical fractures in the orthorhombic medium with considering the factors of the fracture scale and fluid filling simultaneously,and used the reflectivity method to the full wave field seismic forward modeling for calculating and analyzing the AVAZ (amplitude versus azimuth) response of the orthorhombic shale reservoir, so that we could characterize the reservoir fractures with the azimuthal features of amplitude. The result shows that the azimuth-amplitude response of PP, PSV and PSH waves are significantly different from each other, and the fitting shape of the azimuth-amplitude polar diagrams reflect the development direction of fractures. These provide the evidence for seismic recognition of fractures in the shale reservoir.