Frequency-dependent anisotropy can be used for detection and evaluation of fractured reservoirs. In this study, three numerical models of fractured reservoirs are designed to study the frequency dependence of amplitude variation with azimuth (AVAZ). Here, two factors, which can make the AVAZ responses frequency dependent, are taken into consideration, the fluid flow and the tuning effect. Model I is used for the analysis of frequency-dependent AVAZ induced only by the fluid flow. Model II is used to study frequency-dependent AVAZ induced only by the tuning effect. For Model III, these two factors are in the presence at the same time. In this study, the fluid flow is simulated by Chapman’s multi-scale rock physics model, and the azimuthal seismic gathers are generated by propagating matrix method. Spectral decomposition is implemented based on the smoothed pseudo Wigner-Ville distribution, so that the frequency dependence for the AVAZ gathers can be discussed. It is demonstrated that both the fluid flow and the tuning effect can cause significant frequency-dependent AVAZ, and the frequency-dependent AVAZ is helpful for fluid identification and anisotropic thin bed detection. Besides, for both factors, the incident angle can influence the frequency-dependent AVAZ responses, accordingly azimuthal seismic gathers with large incident angles are necessary for field data application.

频率相关的各向异性可用于裂缝性储层的检测和评估。在本研究中，设计了三个裂缝性储层数值模型来研究振幅随方位角变化的频率依赖性 (AVAZ)。在这里，考虑了两个可以使 AVAZ 响应频率相关的因素，流体流量和调谐效果。模型 I 用于分析仅由流体流动引起的频率相关 AVAZ。模型 II 用于研究仅由调谐效应引起的频率相关 AVAZ。对于模型 III，这两个因素同时存在。本研究采用Chapman多尺度岩石物理模型模拟流体流动，采用传播矩阵法生成方位地震道集。频谱分解是基于平滑伪 Wigner-Ville 分布实现的，因此可以讨论 AVAZ 道集的频率依赖性。结果表明，流体流动和调谐效应都会引起显着的频率相关 AVAZ，频率相关的 AVAZ 有助于流体识别和各向异性薄层检测。此外，对于这两个因素，入射角都会影响频率相关的 AVAZ 响应，因此现场数据应用需要大入射角的方位地震道集。频率相关的 AVAZ 有助于流体识别和各向异性薄层检测。此外，对于这两个因素，入射角都会影响频率相关的 AVAZ 响应，因此现场数据应用需要大入射角的方位地震道集。频率相关的 AVAZ 有助于流体识别和各向异性薄层检测。此外，对于这两个因素，入射角都会影响频率相关的 AVAZ 响应，因此现场数据应用需要大入射角的方位地震道集。