一种解耦的起伏地表弹性波高斯束偏移方法

随着勘探开发逐步深入, 成像已逐步从单纯利用纵波数据发展为弹性波数据。针对双重复杂构造探区, 在弹性波高斯束偏移的基本原理中, 引入高程及地表倾角信息, 推导了由高斯束位移矢量表示的解耦弹性波场反向延拓公式, 利用互相关成像条件且通过转换波极性校正得到起伏地表条件下的P-P波和P-S波高斯束偏移算子, 发展了一种解耦的起伏地表弹性波高斯束偏移方法, 此方法无须对地震数据进行纵横波分离。在实现方法的基础上, 通过典型起伏地表模型的弹性波现象分析、成像结果分析及成像角道集提取, 证实了解耦的起伏地表弹性波高斯束偏移成像方法的正确性、适用性及良好的成像效果。

Decoupled elastic Gaussian beam migration for rugged topography

As the development of the seismic exploration, not only acoustic P wave gathers but also elastic wave gathers are inputs for data imaging. Based on surface elevation, surface dip angle, and unseparated multi-component data, we derive decoupled backward-continued vector wavefiled extrapolation formula in terms of elastic-dynamic Gaussian beams by directly decomposing local plane-wave components from complex topography. According to the cross-correlation imaging condition and polarization features of vector wavefield, we obtain PP and polarity-corrected PS migration formulas. We test the proposed method by analyzing elastic wave phenomenon and migrated images, and extracting the ADCIGs from different CDPs for a characteristic rugged topography model data. Numerical results demonstrate the accuracy and flexibility of the method.