常相位校正

Constant phase correction

在做过常规反褶积处理的叠加剖面上,对子波剩余相位进行校正,对于提高剖面的信噪比和分辨率是有意义的。本文介绍的常相位校正是解决这个问题的一种近似方法(因为实际剖面中的子波剩余相位不一定是常数)。校正准则有两种:第一种是以测井合成记录为依据,对井旁地震记录用一定的角度增量进行常相位扫描,与合成记录相似性最好所对应的角度作为整条剖面常相位校正的角度;第二种是在多道记录上进行常相位扫描,用方差最大时所对应的角度作为整条剖面常相位校正的角度。常相位校正是在时间域进行的。文中证明了:一个时间序列,当其为零相位时方差模最大;对记录进行常相位校正不改变记录的包络;在实现常相位校正时,在记录的相位谱上加一个常数与在记录的瞬时相位上加同一个常数,结果是相同的。文中给出的常相位校正剖面的例子,其同相轴连续性、信噪比和分辨率均有明显的提高。

The correction of residual phases of seismic wavelets on stacked section that underwent conventional deconvolution processing is of significance to the improvements of both S/N ratio and resolution of the seismic section. Constant phase correction method recommended here is only an approximation for solving this question because the residual phases of wavelets of real seismic section are not necessarily the constant. There are the following two correction criterions: (1) with the logging synthetic seismic data being a basis, the constant phase sweep of well-side seismic traces is made using a certain angle increment, and the angle which makes the seismic trace most similar to the synthetic seismic data can be used as the angle for the con stant phase correction of whole seismic section; (2)the constant phase sweep is made on multiple traces, and the angle corresponding to the maximum variance norm is the angle that can be used in constant phase correction of whole seismic section. The constant phase correction is performed in time domain. The conclusion is drawn: the maximum variance norm corresponds to a time series with zero phase; the constant phase correction of seismic record does not change its envelope; in constant phase correction of seismic record, the phase spectrum plus a constant and the instantaneous phase plus the same constant can bring the same result. The example is given of the constant phase corrected seismic section whose reflection leg continuity, S/N ratio and resolution are all improved obviously.