Wave-induced fluid flow, an important mechanism in seismic wave attenuation, is considered in the amplitude variation with the offset technique. In a fractured marine carbonate reservoir, fractures and pores develop simultaneously, such that wave-induced flow is an important mechanism in attenuation caused by the fluid flow between pores as well as between pores and fractures. However, these two types of attenuation are typically investigated separately or studies assume that the pores and fractures are dry or saturated by the same fluid. Rock pores are usually saturated by a mixture of two or more fluids, such that the fracture and pore filling fluids may be different. During variation with offset reservoir prediction and fluid identification, the influence that the porosity, fracture, and fluid have on the P-wave reflection coefficient should be considered. The patchy saturation model can describe the seismic wave dissipation caused by the wave-induced flow between pore fluids, whereas the Norris model can describe seismic wave dissipation caused by the fluid flow between fractures and pores. This study considers both the patchy saturation model and Norris model to calculate the amplitude variation with the offset P-wave reflection coefficient under different conditions. Combining the saturation and Norris models forms a new model, which is regarded as a transversely isotropic medium with a vertical symmetric axis, and can be extended to any incident angle through the relaxation function and the high- and low-frequency elastic limits of the stiffness tensor, where the complete effective stiffness tensor of the new model can be obtained. Finally, the amplitude variation with offset reservoir technology is used to determine the influence of model parameters on the reflection coefficient of P-waves under different angles and frequencies, including fracture weakness, fluid saturation and pore fluid saturation.

中文翻译：

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部分饱和裂隙介质中纵波的反射系数

波致流体流动是地震波衰减的一个重要机制，在偏移技术的幅度变化中被考虑。在裂缝性海相碳酸盐岩储层中，裂缝和孔隙同时发育，波激流是孔隙间和孔缝间流体流动引起衰减的重要机制。然而，这两种类型的衰减通常是单独研究的，或者研究假设孔隙和裂缝是干燥的或被同一流体饱和。岩石孔隙通常被两种或多种流体的混合物所饱和，因此裂缝和孔隙填充流体可能不同。在与偏移储层预测和流体识别的变化过程中，孔隙度、裂缝、应考虑流体对纵波反射系数的影响。片状饱和度模型可以描述孔隙流体之间由波浪引起的流动引起的地震波耗散，而Norris模型可以描述裂缝和孔隙之间的流体流动引起的地震波耗散。本研究同时考虑斑片饱和模型和Norris模型来计算不同条件下随偏移纵波反射系数的幅度变化。结合饱和度和诺里斯模型形成一个新的模型，该模型被视为具有垂直对称轴的横向各向同性介质，可以通过松弛函数和刚度的高频和低频弹性极限扩展到任何入射角张量，其中可以得到新模型的完整有效刚度张量。最后，利用偏移储层技术的幅度变化来确定模型参数对不同角度和频率下P波反射系数的影响，包括裂缝弱化、流体饱和度和孔隙流体饱和度。