A new method for first-break picking in refraction exploration
Xu Yu1, Zeng Weihui2, Song Jianguo2, Xu Weixiu1, Chen Nan1
1. Geophysical Exploration & Development Corp.,Shengli Oilfield Administration,Sinopec,Dongyng,Shandong 257100,China;
2. School of Geosciences,China University of Petroleum
Abstract：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.
