基于起伏地表的合成炮叠前深度偏移

Relief surface-based prestack depth migration of synthetic shot records

大量实践表明,基于起伏地表的叠前深度偏移方法要比常规波动方程叠前深度偏移方法的精度高。为了进一步提高叠前深度算法的精度和效率,本文介绍一种基于起伏地表的合成炮叠前深度偏移方法,其基本思路是采用相位编码方法产生合成炮,实现多炮叠前深度偏移,提高了计算效率;用波动方程波场延拓取代浅地表的高程静校正,提高了偏移成像精度。文中给出了基于起伏地表合成炮叠前深度偏移的统一算法和实现步骤。对Marmous模型和山峰形模型的试算及对四川山地实际地震资料处理的结果均表明:本文所述方法运算速度快、成像精度高;只是在合成炮叠前深度偏移剖面上还残留少量由波场合成产生的互相关噪声。

A large amount of practices showed that in comparison with ordinary wave equation prestack depth migration approach, the precision of relief surface-based prestack depth migration is higher. In order to further improve the precision and efficiency of prestack depth algorithm, the paper introduced a relief surface-based prestack depth migration algorithm of synthetic shot records, in which the basic idea is to use phase coding method to produce synthetic shot records, realizing prestack depth migration of multiple shot records and improving the computing efficiency; and to use wave equation wavefield continuation to replace elevation static correction of shallow near-surface, improving the precision of migration imaging. The paper gave uniform algorithm and implementing steps of relief surface-based prestack depth migration of synthetic shot records. The tests of Marmous and mountainous models and processing results of practical seismic data in Sichuan mountainous areas showed the mentioned approach in the paper is characterized by rapid computing speed and higher imaging precision, but remaining a small amount of cross-correlation noise produced by wavefield synthesis on the prestack depth migration sections of synthetic shot records.