Most frequency-dependent AVO inversions are currently based on an approximate equation derived using an isotropic medium. However, actual reservoirs usually show anisotropy, such as shale reservoirs, tight sandstone reservoirs and fractured reservoirs. We propose a joint frequency-dependent AVO (JFAVO) inversion in an anisotropic medium based on a periodic layered double-porosity medium. This JFAVO will allow us to quantitatively study the influence of fluids on the dispersion of PP- and PS-wave velocities and anisotropic parameters. First, we used a double-porosity medium to analyse the frequency-dependent characteristics of velocities and anisotropy parameters. We found that the anisotropic parameters show obvious dispersions, similar to those of velocities. Then, we derived the JFAVO inversion based on Rüger's equation to extract the dispersion of velocities and anisotropic parameters. Finally, we analysed the stability and applicability of the inversion algorithm, and used three sets of models to analyse the sensitivity of dispersion properties to fluids. The numerical analysis results show that PP-wave velocity dispersion and anisotropic parameter δ dispersion are sensitive to fluids, whereas, the velocity dispersion of the PS-wave is not. When saturation exceeds 80%, the velocity dispersion and anisotropic parameter dispersion properties are not sensitive to fluids.

中文翻译：

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部分饱和双孔隙岩石中PP波和PS波的各向异性频率相关特征

大多数频率相关的 AVO 反演目前基于使用各向同性介质导出的近似方程。然而，实际油藏通常表现出各向异性，如页岩油藏、致密砂岩油藏和裂缝性油藏。我们提出了一种基于周期性层状双孔隙度介质的各向异性介质中的联合频率相关 AVO (JFAVO) 反演。该 JFAVO 将使我们能够定量研究流体对 PP 和 PS 波速度和各向异性参数的分散的影响。首先，我们使用双孔隙度介质来分析速度和各向异性参数的频率相关特性。我们发现各向异性参数显示出明显的分散，类似于速度。然后，我们推导出了基于 Rüger' 的 JFAVO 反演 s 方程来提取速度和各向异性参数的分散。最后，我们分析了反演算法的稳定性和适用性，并使用三组模型分析了色散特性对流体的敏感性。数值分析结果表明，PP波速度色散和各向异性参数δ色散对流体敏感，而PS波的速度色散则不敏感。当饱和度超过 80% 时，速度色散和各向异性参数色散特性对流体不敏感。数值分析结果表明，PP波速度色散和各向异性参数δ色散对流体敏感，而PS波的速度色散则不敏感。当饱和度超过 80% 时，速度色散和各向异性参数色散特性对流体不敏感。数值分析结果表明，PP波速度色散和各向异性参数δ色散对流体敏感，而PS波的速度色散则不敏感。当饱和度超过 80% 时，速度色散和各向异性参数色散特性对流体不敏感。