海上拖缆双源随机激发地震混合采集及波场分离

Dual-source with random shooting blended towed streamer seismic acquisition and deblending

海上拖缆多震源混合采集技术因其能提高采集密度和覆盖次数而在国外得到发展和应用,但在国内尚处于研究和试验阶段。这里结合国内实施的海上拖缆双源随机激发地震混合采集试验的数据结果,阐述了多震源激发延迟时间的设置、多震源波场分离关键技术。首先基于多震源分离准则优选了拖缆双源随机激发延迟时间,并在南海进行了双源随机激发拖缆三维采集试验,获得了混合震源地震数据;然后利用混叠噪声在非炮域离散不相关的特点,在共偏移距域采用迭代多方向矢量中值滤波去噪,实现了混合数据的波场分离,得到了单炮记录。为了与常规采集效果对比,使用跟常规地震资料同样的处理流程和参数,进行了各种噪声压制及叠前时间偏移处理。与常规采集的资料处理结果对比表明,拖缆双源随机激发地震资料信噪比得到了提高,成像得到了改善,尤其是断面、断层阴影区、古近系地层和洼陷内幕结构成像改善较大。

The blended seismic acquisition technology of marine streamers has been developed and applied abroad because it can improve the acquisition density and folds,but it is still in the research and testing stage in China.Combined with the data results of the offshore streamer dual source random shooting blended seismic acquisition test carried out in China,the setting of multi-source shooting delay time and the critical technology of multi-source wave field separation are described in this paper.Firstly,the delay time of dual streamer source random shooting is optimized based on the multi-source separation criterion,and the 3D acquisition experiment of dual source random shooting streamers is conducted in the South China Sea for the first time.The seismic data of mixed sources are obtained.Then,the iterative multi-direction vector median filter is used to de-noise in the common offset domain by using the characteristics that the aliasing noise is discrete and uncorrelated in the non-shot domain.The wave field is separated,and the single shot record is obtained.In order to compare with conventional seismic data acquisition,noise suppression and pre-stack time migration are carried out using the same processing flow and parameters as conventional seismic data.Compared with the conventional data processing results,the signal-to-noise ratio(SNR)of the dual streamer source random shooting seismic data has been improved,and the imaging has been improved,especially for the cross-section,fault shadow area,Paleogene strata,and depression interior structure.