针对海洋水层反射的处理方法研究

Method for processing the seismic reflection of sea water

在海洋地震勘探过程中,逐步发展到可以利用反射地震法研究海洋水体运动现象及海水温盐结构,而处理好水体反射信号则是地震海洋学研究的关键.目前地震海洋学正处在起步阶段,鲜有专门针对水层反射的处理方法研究,本文根据水体反射特征,形成了专门针对水体反射的处理技术.首先,与海底地层反射不同,因水介质间差异较小,水层反射信号相对较弱,常规地震处理技术直接应用到水层反射难以取得预期处理效果.针对这一特点,本文提出了水层弱信号保护技术,通过有效分离水层反射信号达到保真效果;其次,常规海洋地震勘探中使用的空气枪震源位于水下一定深度,激发过程中产生强烈的气泡效应,对水层有效弱信号干扰极强,本文在单子波气泡效应压制的基础上,利用分段提取多子波的方式,对气泡效应进行分段压制,避免因子波发生变化影响处理结果;针对水层噪声强、信噪比低的特点,利用高精度LIFT技术去噪得到高品质道集;最后,利用鬼波压制技术消除鬼波调谐效应,提高地震资料的分辨率.在这些处理技术应用的基础上,本文总结了一套针对水层弱反射的处理流程,并且在海洋地震资料水体反射处理中取得了较好的应用效果.

During the process of marine seismic exploration,the method of reflection seismic can be used to study the phenomena of marine water movement and the water structure of temperature and salinity. The key to study seismic oceanography is processing the reflected signals of water. At present,seismic oceanography is in its infancy,and few methods have been developed to process the reflection of water layer. Based on the characteristics of water reflection,new techniques for water reflection have been developed.First of all, different from the seabed reflection, the water reflection,due to its small water medium difference,is relatively weak, and conventional seismic processing method can hardly achieve desired effect when it is directly used to process water reflection. So the paper proposed a method of weak signal protection to achieve true signal by separating signal from noise. Secondly,the use of air gun in conventional marine seismic exploration generates strong bubbles,this paper extract multiple wavelets to suppress the bubbles instead of using single wavelet, avoiding ignoring the wavelet change of the seismic data. Denoise with LIFT technology since the low signal-to-noise ratio and it will separate signal from noise until no signal can be separated. Finally,deghost to suppress the tuning effect caused by the ghost wave,and it will enhance resolution. Based on the application of these processing methods,this paper present a set of processing procedures for weak reflection of water layer and has achieved good results in marine seismic data processing.