白云凹陷陆架—陆坡区多次波压制技术

白云凹陷位于中国南海北部陆架—陆坡区，由于水深变化剧烈，目标区地震资料中发育的表面多次波周期变化大，较难压制。传统的预测反褶积、SRME、Radon技术及其组合，压制这种水深变化剧烈的多次波效果不佳。为此，对近年发展的一种浅水表面多次波压制技术即确定性水层多次波压制技术DWD进行了研究，提出将其与SRME和Radon传统方法联合的多次波压制思路。DWD方法是先从水速动校后的最小炮检距的自相关剖面上拾取水底双程反射时间，然后在近道外推后将t-x域地震数据变换到τ-p域，再在τ-p域通过波场外推预测出多次波模型，最后与原始数据进行自适应匹配相减压制多次波。处理结果表明，DWD+SRME+Radon方法组合能有效地压制白云凹陷目标区多次波。与原处理剖面相比，此次处理后的成果剖面品质明显提高，降低了解释风险；同时，用此次处理得到的偏移道集进行叠前波阻抗反演，结果较好地刻画了目标砂体的特征和边界。

Multiple suppression in continental shelf and slope areas of Baiyun Depression

Due to dramatically changing water depth, different-period surface-related multiples exist on seismic data in Baiyun Depression located in the continental shelf-slope zone of northern South China Sea.This kind of multiples are very difficult to be suppressed with conventional techniques, such as predictive deconvolution, surface-related multiple elimination (SRME), Radon transform, and their combination.Therefore we propose in this paper a new idea called deterministic water-layer demultiple (DWD).Firstly we pick water bottom two-way reflection time from auto-correlated data on water-velocity NMO at minimum offsets, then transform t-x domain seismic data into tau-p domain data after near-offset extrapolation.After that, we predict multiple model with wavefield extrapolation.And finally we suppress multiples with adaptive matching subtraction from original data.We combine the approach with SRME and Radon transform.Our applications indicate that the combined approach eliminates effectively different-period surface-related multiples.Compared with the conventional processed sections, high-quality sections processed are obtained with the proposed approach, which reduces the risk of seismic interpretation.Meanwhile, prestack gathers inversions based on this processing can well depict sand body characteristics and their boundary.