不同的地震弹性阻抗反演软件计算弹性阻抗的方法不尽相同，地震弹性阻抗反演中尚有一些应用条件在没有详细讨论的情况下被简单地加以应用，这给实际生产带来了困难。有鉴于此，以典型的4 种不同类型含气砂岩模型为基础，分析比较了弹性阻抗、反射阻抗和广义弹性阻抗在不同角度下的计算精度；并且基于Biot-Gassman 理论，对Ostrander 含气砂岩模型进行流体替代，探讨了含水饱和度由小变大时不同的弹性阻抗对流体的敏感性。通过4 种不同类型含气砂岩模型计算可知：在第Ⅰ类和第Ⅳ类含气砂岩中，入射角不超过40° 时，EI，RI 和GEI 均能替代Zoeppritz 方程；在第Ⅱ类含气砂岩中，入射角不超过30° 时，EI，RI，GEI 也能替代Zoeppritz 方程；这3 种弹性阻抗无法应用于第Ⅲ类含气砂岩。将偏导的思想应用到Ostrander 含气砂岩模型，计算结果表明，反射阻抗对流体的敏感性强于弹性阻抗和广义弹性阻抗，
且入射角越大，这种敏感性越强。

Presently, there are variously methods for calculating elastic impedance by different seismic elastic impedance inversion softwares, and seismic elas tic impedance inversion were often simply applied though some requirements hadn’t been discussed in detail, which causes yield difficulties for actual productions. Therefore, based on four typical types of gas-bearing sandstone models, calculation accuracy of elastic impedance（EI）, reflected impedance（RI） and generalized elastic impedance （GEI） are analyzed and compared. Moreover, based on Biot-Gassman theory, fluid replacement is applied for gas-bearing sandstones model advanced by Ostrander, and the sensitivity to fluid of different elastic impedance is discussed when water saturation changed. The following conclusions can be obtained through the calculation of four types of gas-bearing sandstone models: As for Class Ⅰ and Class Ⅳ, Zoeppritz equations can be substituted forthe EI, RI and GEI when the incident angle is less than 40 ;As forClass Ⅱ, Zoppritz equations can also be substituted when the incident angle is less than 30 ; However, these three kinds of elastic impedance can not be applied for Class Ⅲ; The idea of the partial derivative is applied for the gas-bearing sandstone models advanced by Ostrander, the result shows that, RI is more sensitive to fluid than EI and GEI as incident angle is bigger.