浅海地震数据中的拍振现象与时滞−对数域压制

浅海地震勘探中，如果鸣震和气泡满足一定的条件，将会产生拍振，产生一种能量很强的低频混响，其振幅强弱变化呈现明显的拍振包络趋势。常规的预测反褶积和利用远场子波的确定性反褶积等方法在压制这种噪声时效果均不理想。雷克子波反褶积方法在压制海上地震勘探气泡效应时具有较好的效果。基于CLAERBOUT理论，提出时滞−对数域滤波压制拍振包络中的低频混响的方法，重新定义了时滞−对数域中的时滞信号的内容，划分了小时滞信号、中时滞信号和大时滞信号。根据信号在时滞−对数域的不同分布，设计滤波器压制拍振包络中的低频混响噪声，取得了很好的噪声压制效果。利用时滞−对数域滤波方法和其他几种方法对实际数据进行处理，处理结果充分显示了时滞−对数域滤波方法在压制拍振包络中的低频混响方面的优势。

Ringing and bubble noises common in shallow water seismic exploration may lead to strong low-frequency reverberations with periodic increase and decrease in envelope amplitude in seismic data. Conventional deterministic deconvolution using far-field wavelets and predictive deconvolution do not have good performance for suppressing such noises. The Ricker-compliant deconvolution method proposed by Claerbout is a paradigm for suppressing bubble effects in offshore seismic data. Based on the Claerbout's theory, this paper proposes a lag-log domain filter to suppress low-frequency reverberations in beat envelope amplitude, redefines the medium-time-delay signal in the lag-log domain, and divides the data into small-lag signals, medium-lag signals and large-lag signals. According to different signal distributions, a Kolmogorov filter is constructed to remove medium- and large-lag signals, or reverberations and bubbles. Testing results show that lag-log domain filtering gets a good result in suppressing low-frequency reverberations in beat envelope. A comparative study of real data processing shows that lag-log domain filtering performs better than several other methods in the suppression of low-frequency reverberations.