最小二乘反演迭代算法在压制海上变深度缆采集数据虚反射中的应用

海水面的虚反射(鬼波)引起海上拖缆采集数据陷波,导致地震记录频带变窄,而近年发展的变深度缆采集技术,具有多样的陷波特征,通过专门的去虚反射处理方法可获得宽频数据.本文基于已有研究成果,将最小二乘反演迭代压制虚反射算法应用于某海上变深度缆宽频处理.基于频率波数域镜像记录生成方法获得镜像炮集记录,并采用最小二乘解从变深度缆原始和镜像炮集记录中提取上行波.针对镜像炮集记录生成受初始速度模型精度的影响,使得某深度缆接收的上行波和下行波之间的实际延迟时间存在误差,采用最小二乘反演迭代算法最优化计算下行波与上行波之间的平均延迟时间和上行波记录,并采用时空数据窗口滑动克服延迟时间随炮检距和目的层深度变化问题.合成数据及某海上实际变深度缆数据处理测试结果表明,该方法能较好地压制变深度缆由海水面产生的虚反射,能达到拓宽地震记录频带目的.

The application of least-squares inversion iteration algorithm to deghost for marine variable-depth streamer data

There is notch in marine towed-streamer data because of the ghost effects of the sea surface,which make the frequency bandwidth of seismic data narrow. The variable-depth streamer (VDS) acquisition technology has gained considerable development in recent years, which is characterized by various notches. The broadband data can be obtained by special deghosting method. Based on previous research achievements, a least squares inversion iteration algorithm is applied to deghost for marine variable-depth streamer data in this paper. The mirror shot gather data can be produced in frequency-wave-number domain. The up-going wave can be extracted by using least squares solution for the original and mirror data in shot domain from VDS acquisition data. Then, for the error of actual delay time between up-going wave and down-going wave received at a depth caused by inaccurate initial velocity model for generating mirror data in shot domain, the average delay time between up-going wave and down-going wave and the up-going wave are optimally calculated by applying least squares inversion iteration algorithm. Moreover, the sliding window in space and time is used to overcome the time delay variation with offset and target layer depth. The test results of synthetic and marine actual VDS seismic records processing show that the method can effectively suppress ghost produced on the sea surface in marine VDS data and achieve the purpose of broadband seismic data.