海洋地震变深度电缆采集数据的频谱分析及消除鬼波研究

The frequency analysis of VDS and its application to deghosting

为拓宽有利于地震成像的频带范围,特别是拓宽对中深层地质构造成像有利的低频,物探工程师提出和改进了很多采集技术与方法,其中较为成功的技术是斜缆宽频采集技术,其原理是斜缆采集使得虚反射的陷波频率点不同。笔者重点分析了变深度电缆对地震资料频谱特征尤其是低频的影响,提出振幅曲线的陡度函数是测量信号在低频端丰富程度的有效方法,并通过模型正演比较了由等深的水平缆和变深度的斜缆采集的地震道频谱特征;然后针对虚反射引起的鬼波难题,采用修改的线性最小平方Radon变换方程来消除虚反射产生的鬼波,然后分别应用于正演模型和实际的南海斜缆地震资料,均取得较好的去鬼波效果。

The quality of seismic data has been improved with the application of variable-depth streamers（VDS）acquisition,which leads to diversity of receiver ghost notch,and the key advantage is the utilization of notch diversity to combine different depth receivers,thus achieving the final better result which has no notches.This paper focuses on the effects of VDS acquisition on frequencies especially on low frequencies that benefit the images of deep geological structure.The slope function provided by this paper can effectively gauge the extent of low frequencies,and it is easy to find the frequency difference between shots modeled by conventional constant depth streamer（CDS）and ones modeled by VDS;In addition,considering the ghosts caused by the marine free surface,the method outlined in this paper derives a surface datum ghost free result of input shot gather data by using the modified least squares linear Radon equations.Its application to model data and real VDS seismic data shows that this deghost algorithm can effectively suppress the ghosts.