海上上下缆地震采集资料特点分析

The Analysis of Seismic Data Characteristics by Over/Under Towed-streamer Acquisition

受海水面的虚反射影响,常规海上拖缆采集的数据存在陷波特性,使得地震记录的频带变窄,降低了地震剖面的分辨率。近几年,上下缆采集技术已得到长足的发展,在国外取得了较好的应用效果,为了充分利用上下缆采集的资料信息,指导上下缆资料的处理,本文通过频率波数谱分析了上下缆采集资料的特征,同时分析了上下缆采集资料信噪比特征,分析结果表明,相同震源沉放深度情形下,电缆沉放深度的增加,不仅低频能量增强,而且提高了信噪比,有利于中深层采集信号能量增强;但由于低频能量减弱,使得整体频带变窄,勘探分辨率降低;同时,上下缆资料的合并处理必须考虑不同缆处的噪声所带来的影响。

Because of the effects of the ghost reflection of the sea surface,the data of conventional towing collection at sea have the trapped features,which reduces the frequency band of the seismic data and the resolution of the seismic profile.Up and down streamer acquisition technology has been rapid developed in recent years,having achieved a good effect abroad.In order to take full advantage of the data and information by over and under streamer acquisition and to guide the data processing.In the paper,we analyze the features of the seismic data by up and down acquisition in the 1Dfrequency spectra and 2Dfrequency-wave-number spectra,at the same time we analyze the features of signal-to-noise ratio of the data.The results show that the low-frequency energy is enhanced and also increase the SNR with the cable depth increasing under the same source depth,which is benefit to enhance the reflected energy on deep layers.But the whole band is narrowed and the exploration resolution reduced due to the low-frequency energy is weakened.At the same time,the merging processing of over and under towed-streamer acquisition data must consider the impact of the presence of noise in these towed-streamers.