【摘要】 对于高速屏蔽层下伏的低速层,采用广角地震勘探是一种有效的地震勘探方法。但在广角条件下,反射波与入射波存在相位差,反射系数变为复数,波动力学特征非常复杂,给实际地震资料的识别、处理、解释带来困难。在介质弹性参数λ,μ和σ确定、波速与密度相对变化的条件下,本文从Zoeppritz方程出发,运用数值模拟的方法模拟了超临界角地震波的传播规律。表明当P波入射角等于或大于临界角时,波的性质发生变化,反射系数成为复数,地面难以接收,而透射S波能量较强,可利用转换波探测高速屏蔽层下伏低速层界面的信息;采用带有各向异性参数的四阶动校正公式(Alkhalifah方法、Hake公式、Castle公式)对大炮检距的地震数据进行校正,验证了带有各向异性参数的高阶动校正在大炮检距处的校正效果明显优于常规动校正效果。更多还原

【Abstract】 For underlying lower-velocity layers shielded by high-velocity layers, the wide-angle seismic exploration is effective seismic exploration approach. But under the wide-angle condition, the phase difference exists between the reflected and incident waves,making the reflection coefficients complex and the feature of wave dynamics very complicated, bringing difficulty to identification, processing and interpretation of practical seismic data. In the conditions that the elastic parameters of medium λ,μ and σ are determined,wave velocity and dense of medium relatively change, the paper, coming from the Zoeppritz equation, uses the method of numeric simulation to simulate the propagation rule of supercritical seismic waves, which showed,when P-wave incident angles are equal to or great than critical angle, the properties of wave change, the reflection coefficients become complex, which made receiving of reflections on surface difficult,but the transmitted S-wave has strong energy that can be used for detection of information in underlying low-velocity layers shielded by high-velocity layers. It is proved, by using 4-order NMO formula with anisotropic parameters (Alkhalifah method, Hake formula and Castle formula) to carry out correction for seismic data with large offsets, the corrected effects of high-order NMO formula with anisotropic parameters are obviously superior to that of ordinary NMO formula at large offsets.更多还原