频率域起伏双缆数据合并策略

受鬼波和陷波现象的影响,常规海洋拖缆采集地震记录分辨率低,频带较窄,低频端能量不足,因此常用的上下缆宽频采集技术及其数据合并方法成为海洋地球物理勘探研究重点之一。为此,提出了频率域起伏双缆合并策略。通过计算每个检波点处的鬼波算子,自适应地对起伏双缆进行合并,在减小缆深起伏对合并质量影响的同时,最大限度利用每个检波点信息以提高合并结果分辨率和信噪比。对于实际计算中鬼波算子存在奇异的情况,通过引入白噪因子,提高了计算的稳定性。并提出了利用浅缆补偿变深度拖缆高频端能量的采集技术,为高精度海洋地震勘探提供了新的思路。最后,分别选取起伏缆深上下缆拖缆模型、浅缆补偿变深度拖缆模型以及海上实际上下缆数据为例,验证了频率域起伏双缆合并策略的有效性。结果表明,鬼波被很好地去除,陷波现象被压制,低频端能量得以提升,地震记录频带也得到了有效拓宽。

 Conventional streamer seismic acquisition suffers from the sea surface ghost and resulting notches,which results in poor resolution,narrow band and less low-frequency components for seismic data.As a common broadband seismic acquisition,over/under towed-streamers acquisition technique and its data merge are focused in marine geophysical research.We propose a data merge strategy for fluctuate double streamers in frequency domain.By estimating the ghost operator in every seismic geophone,the new strategy self-adaptively merges the two streamer data and reduces the equivalent notch effect to a theoretical minimum,while the information of all receiver points are utilized to improve the resolution and signal-to-noise ratio of merged results.For the case of singular ghost operator,the white noise coefficient is introduced and the stability of the calculation is improved.Variable-depth streamers could also be combined with a shallow streamer to strengthen its high-frequency energy,which provides a new thinking and well supplement in real high precision marine seismic exploration.We applied this strategy to both synthetic data examples from rough over/under towed-streamers,new proposed over/variable-depth streamers models and a real seismic data case.Good results for the synthetic and real data cases were achieved.The ghost is removed,notches are suppressed,band is broadened and the energy of low-frequency components is improved.

国家科技重大专项项目(2011ZX05025-001-04)资助。