地震测井走时的二阶导数在确定井孔速度结构中的应用  

Application of second derivative method of traveltime to determine velocity structure in seismic logging

作　　者：余松平 高雯琪 王有学[1,2] 任乾慈 郭咏欣 YU Song-ping;GAO Wen-qi;WANG You-xue;REN Qian-ci;GUO Yong-xin(College of Earth Sciences,Guilin University of Technology,Guilin 541006,China;Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,Guilin University of Technology,Guilin 541006,China)

机构地区：[1]桂林理工大学地球科学学院,广西桂林541006 [2]桂林理工大学广西隐伏金属矿产勘查重点实验室,广西桂林541006

出　　处：《桂林理工大学学报》2022年第2期348-353,共6页Journal of Guilin University of Technology

基　　金：国家自然科学基金项目(41574030,41174077,41674075);广西自然科学基金重点基金项目(2016GXNSFDA380014)。

摘　　要：针对常规地震波速测井过程中走时拾取存在一定误差,处理结果会产生一些虚假的地层分界,难以满足地球物理勘探的需求,提出一种基于地表激发、井中接收的地震波测井数据,利用地震波的走时曲线在地层分界面处其二阶导数出现极大值的特征及上、下地层速度的“判别值C”对井中地层分界进行判定,再根据相邻界面之间的走时数据段所得平均速度,对井中地层速度变化自上而下进行反演的方法。结果表明,本文方法反演得出的井中地层层速度曲线与理论模型基本吻合,深度和层速度的最大误差分别为0.5 m、14.22 m/s;在理论走时数据中加入5%随机扰动,仍能较好地反演出井中地层速度结构特征;应用该方法对井中的速度分布进行反演,得到的速度曲线与岩心资料具有较好的对应关系。该方法简便、快捷,能够较准确地刻画测井地层的变化情况与速度结构。Due to some limitations,such as picking errors for traveltimes from the seismic logging data,the conventional seismic logging will produce some false stratigraphic boundaries,and the results are difficult to meet the needs of geophysical exploration.Based on the seismic logging data excited at the surface and received in the well,and this paper proposed a new method,which uses the characteristics of the second derivative of seismic traveltimes and the“threshold C”indicating the velocity contrast between the upper and current layer,to determine the velocity discontinuities.The results from theoretical data and observed seismic logging data shown that consistent with the theoretical model basically.The maximum error of the depth is 0.5 m,and the maximum error of the layer velocity is 14.22 m/s.After adding 5%random disturbance in the theoretical traveltime data,it is still possible to invert the good velocity structural characteristics in the well.This method is simple,fast,and can produce a very well velocity structure for seismic logging accurately.

关 键 词：地震测井 二阶导数 判别值C 速度结构 

分 类 号：P631.4[天文地球—地质矿产勘探]