The accumulation of organic matter is the basis for gas generation and significantly affects the ultimate gas production in shale reservoirs. Estimation of organic enrichment using seismic data is essential for shale gas characterization. The commonly used correlations between elastic properties and organic matter content for a particular area are locally applicable but may not be workable for other zones. Herein, a general physics-based approach is proposed to predict organic enrichment in shales. An organic matter-matrix decoupling amplitude variation versus offset (AVO) formula is constructed to straightforwardly quantify seismic signatures of organic matter via an introduced organic matter-related factor (M_c). Then, the elastic impedance (EI) function is established from the decoupling AVO formula to compute M_c. The proposed EI inversion method is suitable for capturing organic enrichment, particularly in the case of inadequate petrophysics information for reliable evaluation of M_c using log data as a constraint in the inversion. The developed AVO formula and EI function regard the organic matter as solid pore-fillings, presenting a more reasonable model for organic shales. Numerical tests show that M_c exhibits enhanced sensitivity to organic matter content with respect to the regularly used elastic properties. The real data applications indicate that the estimated M_c agrees well with the gas production in horizontal development wells, suggesting that M_c is a good indicator of favorable gas areas. The proposed approach may have broader potential applications and can be extended to detect other fluids and solid-saturated hydrocarbon reservoirs such as shale oil, heavy oil, and gas hydrates.

有机质的聚集是页岩气生成的基础，显着影响页岩储层的最终产气量。使用地震数据估算有机质富集度对于页岩气表征至关重要。特定区域的弹性特性和有机质含量之间常用的相关性在当地适用，但可能不适用于其他区域。本文提出了一种基于物理的通用方法来预测页岩中的有机富集度。构建有机物基质解耦振幅变化与偏移量 (AVO) 公式，通过引入有机物相关因子 ( M _c ) 直接量化有机物的地震特征。然后，根据解耦AVO公式建立弹性阻抗(EI)函数来计算M _c。所提出的 EI 反演方法适用于捕获有机富集度，特别是在岩石物理信息不足的情况下，无法使用测井数据作为反演中的约束来可靠地评估M _c 。开发的AVO公式和EI函数将有机质视为固体孔隙充填物，为有机页岩提供了更为合理的模型。数值测试表明，相对于常用的弹性性能， M _c对有机物含量表现出更高的敏感性。实际数据应用表明，估算的M _c与水平开发井的产气量非常吻合，这表明M _c是有利天然气区域的良好指标。所提出的方法可能具有更广泛的潜在应用，并且可以扩展到检测其他流体和固体饱和碳氢化合物储层，例如页岩油、重油和天然气水合物。