采集脚印自适应压制方法

Adaptive suppression for seismic acquisition footprints

海上拖缆地震资料采集受潮汐、海水速度变化、拖缆漂移等因素影响,条带状采集脚印噪声发育。应用三维频率-波数域滤波、时间切片的二维波数域滤波等叠后压制方法时滤波器设置复杂,而且对与有效信号重叠的低波数采集脚印噪声的压制能力较弱。提出了基于时间切片的采集脚印噪声自适应压制方法,该方法通过拉普拉斯算子识别采集脚印噪声,将噪声变换至波数域并根据采集脚印波数谱阈值自适应设置该时间切片的波数域滤波器,进而通过波数域滤波完成采集脚印噪声压制。海上应用实例表明,本方法不仅能够压制高波数采集脚印与随机噪声,对与地震信号重叠的低波数采集脚印噪声也能实现有效压制。

Towed streamer seismic data suffer from an acquisition footprint problem caused by tides,water velocity,depth variation of streamers, etc. Conventional posvstack footprint suppression methods, e.g., FKK filtering and T-Kx-Ky filtering, usually have complicated filtering settings and encounter difficulty suppressing low wavenumber components of the acquisition footprint that overlap signals. For this situation, an adaptive suppression method for acquisition footprint noises is proposed based on time slicing. First, the method identifies footprint noises by a Laplacian operator and transforms the noise into the wavenumber domain. Next, the method adaptively sets the wavenumber filter of the time slice according to the threshold of the wavenumber spectrum of the acquisition footprint,and it then suppresses the footprint noise by wavenumber filtering. Applications of towed streamer seismic data indicated that the method could suppress the high-wavenumber components of the acquisition footprint and random noises. Moreover,it could attenuate the low-wavenumber footprints that overlaps the seismic signals.