浅层折射波勘探中初至自动拾取新算法

A new method for first-break picking in refraction exploration

地震波初至拾取是地震勘探中广泛应用的基础技术,尤其在浅层折射波勘探和层析成像中初至时间拾取精度直接影响地下地层结构的反演结果。由于初至时间对应的并不总是能量比最大值(可能是次极值),以往的滑动时窗能量比法仅根据前后两个滑动时窗能量比的最大值判断初至时间,造成对低信噪比数据的拾取效果不理想,而对高信噪比数据则难以检测能量较弱的折射波。基于此,本文提出多时窗能量比初至拾取算法,该算法在实现过程中结合应用自动质量控制技术,满足了浅层折射波勘探的初至拾取精度要求,且具有较高的稳定性。将该方法应用于准噶尔盆地中部M区地震勘探,取得了非常好的效果。

The first-break picking is a basic technique widely used for seismic exploration.Especially it plays an important role in refraction wave exploration and tomographic imaging.In the exploration interpretation,first-break times are directly related to the inversion result of the underground formation's velocity or slowness.In a conventional way,first-breaks in the sliding time-windows energy ratio method are determined by the maximum energy ratio of two adjacent sliding time-windows.For low S/N data,the picking up effect is not ideal.For high S/N data,it often fails to detect the weak refraction waves.The first arrival time is not necessarily corresponding to the energy ratio maximum value(they may be secondary time energy ratio of extreme value).Therefore,the sliding time-windows energy ratio of first-break picking algorithm is not stable.Based on this cognition,we put forward multi time-windows energy ratio of first-break picking algorithm.The method has the advantage of higher stability.It combines with automatic quality control technology in the implementation process of algorithm,and meets the first-break picking request of the shallow refraction wave exploration.This method is applied to the exploration of the central part of Junggar Basin,and the results are encouraging.