平行径向道时频峰值滤波消减地震资料的随机噪声

Reduction of random noise in seismic data by parallel radial-trace time-frequency peak filtering

针对传统时频峰值滤波(TFPF)算法在消减地震勘探资料中的随机噪声时,容易引起有效信号波峰和波谷处的误差问题,提出了平行径向道TFPF方法。该方法将地震信号从炮检距-双程旅行时域变换到视速度-双程旅行时域后,沿时空域径向道方向进行TFPF。讨论了不同径向道轨线对TFPF无偏估计的影响,并对人工合成的地震记录进行了仿真试验,将沿不同轨线的平行径向道TFPF与传统TFPF结果进行比较。结果表明:所选轨线平行于同相轴或与之夹角很小时,可使信号在一个TFPF时窗内更好地满足无偏估计的条件,从而减小了滤波后波峰及波谷处的误差,使本文方法具有更好的保幅性,其信噪比较传统TFPF算法提高了5dB左右,通过对实际地震记录的仿真,证明了该方法的实用性。

Traditional Time-frequency Peak Filtering （TFPF） usually causes errors at peaks and valleys of valid signal. This study proposed a parallel Radial Trace Transform （RTT）-TFPF with x- interpolation method to reduce these errors. The proposed method uses TFPF to eliminate noise after mapping seismic signals from coordinates of offset and traveltime to those of apparent velocity and traveltime, namely filtering the signals along the direction of the radial trace in the time-space domain. The effect of the different slope of radial trace on the unbiased estimation of TFPF was discussed. Simulation experiments of synthetic seismogram were carried out to compare the traditional TFPF and the RTT-TFPF with different slopes. The results show that when the selected radial traces and events are parallel or the angles between them are small, the proposed method can make the signals better meet the condition of unbiased estimation in one window length, reduce the errors of the peaks and valleys of filtered signal, and improve the property of amplitude-preservation, the SNR of the proposed method can increase about 5 dB.