基于地震DNA算法的一种新的初至拾取方法  

New method of first break picking based on seismic DNA algorithm

作　　者：许鑫 张凯[1] 王非翊 李振春[1] XU Xin;ZHANG Kai;WANG Fei-yi;LI Zhen-chun(College of Earth Science and Technology,China University of Petroleum,Qingdao 266580,China)

机构地区：[1]中国石油大学(华东)地球科学与技术学院,青岛266580

出　　处：《地球物理学进展》2020年第5期1894-1901,共8页Progress in Geophysics

基　　金：中国石油天然气集团公司项目“深层与非常规物探新技术新方法”(2019A-33)资助.

摘　　要：高效准确地拾取初至是获得良好初至波走时层析结果的前提.目前应用广泛的是传统能量比法拾取初至,这种方法是基于获得较准的初至起跳时间.但由于理论缺陷,能量比法拾取的起跳时间并非真实的初至起跳时间.基于聚类连接算法的地震DNA算法是目前比较新颖的层位自动提取方法,尝试将地震DNA算法用于准确地拾取初至,这种初至拾取方法无需获得初至起跳时间,弥补了能量比法的理论缺陷.首先将地震记录从数值空间转换至字符空间,设置符合初至特征的搜索因子在字符空间逐道进行初至拾取,此时所拾取初至为字符类型,使用欧式距离连接聚类好的字符初至使其具有更好的连续性和准确性,然后将字符类型初至转换到数值空间进行初至走时的显示及其计算.对简单数据模型和实际资料分别用传统能量比法与新方法进行初至拾取效果对比,对实际资料的单炮记录分别使用能量比法,互相关法,自拾取算法以及人工干预的自拾取算法进行初至拾取效果对比,拾取初至特征值对比结果说明采用地震DNA算法拾取初至的方法避免了误拾取现象且拾取效果更加连续.对所拾取的初至特征值进一步处理计算走时,将计算得到的初至走时应用于二维初至波走时层析中,层析反演结果表明,这种新的初至拾取方法的具有有效性和可行性.Picking first break in an efficient and accurate way reprensents the prerequisite for obtaining good result of first-break travel time tomography.Currently,the traditional method of energy ratio represents a widely used method to pick first break.This method works based on the obtention of a relatively accurate first break take-off time,which,however,due to the theoretical defect,is not the real take-off time.The seismic DNA algorithm on the basis of the clustering connection algorithm reprensents a currently new method for layer picking.This method resorts to the seismic DNA algorithm to pick first break accurately without the need to obtain first break take-off time,which makes up for the theoretical shortcomings of energy ratio method.In this method,firstly,the seismic profile is converted from the numerical space to the character space,and the searching factor which matches the first break feature is set to be picked up progressively in the character space.At this time,the first arrival is the character type,and the clustering is performed using the Euclidean distance to make the picking result more continuous and accurate,then convert first break from the character type to the numerical space for its display and its travel time calculation.The traditional energy ratio method and the new method are used into simple single shot profile to compare the effect of first break picking.The first arrival waves in the single shot records of the actual data are respectively picked by the energy ratio method,cross-correlation method,self-picking algorithm,and self-picking algorithm of manual intervention.The comparison of first break picking result shows that the new method avoids the wrong picking phenomenon and the picking effect is more continuous.The first break travel time calculated by the new method is applied into the two-dimensional first break wave travel time tomography.The tomographic results show that the new first arrival picking method is effective and feasible.

关 键 词：初至拾取 初至波走时层析 地震DNA算法 聚类连接算法 欧式距离 

分 类 号：P631[天文地球—地质矿产勘探]