基于双平方根方程的双域保幅地震偏移方法

从全声波方程出发，基于严格的解耦理论进行单程波保幅分解，得到保幅的单程波动方程；然后按照叠前深度偏移中的波场双重向下延拓理论实现共炮域公式到CMP域公式的转换，推导出由双平方根方程定义的保幅单程波动方程；基于反问题求解中常用的摄动理论，把速度场分裂为层内常速背景和变速扰动，分别在频率波数域和频率空间域求得波场深度延拓的偏移时移量及振幅校正系数，得到最终的双域保幅波场延拓算子。理论模型试算和实际资料处理表明，该方法不但具有较高成像精度，而且可以为后续的地震属性分析提供更真实的振幅信息。

Method of dual-domain preserved-amplitude based on double-square-root equation for seismic migration

Based on strict decoupling theory, we firstly derive the one-way wave equation started from full a- coustic wave equation using one-way wave/s preserved-amplitude decomposition in this paper. According to the theory of double downward continuation of wavefield in prestack depth migration, we achieve the formula transformation from common-shot domain to common-middle-point domain, and then derive one-way wave equation of preserved- amplitude defined by DSR equation. According to the perturbation theory of seismic wave, we split the velocity field into intraformational constant velocity background and variable velocity disturbance, and then calculate time-shift quantity of migration and amplitude correction coefficients for wavefield continuation in frequency-wave number domain and frequency-spatial domain, respectively, to obtain the final DSR preserved amplitude field continuation operation. Theoretical model testing and real data processing indicate that this method can not only has high accuracy of imaging ,but also provide correct amplitude information for the following attribute analysis.