计算水平层状VTI介质中P波旅行时的近似公式  

Approximate equation for calculating P⁃wave traveltime in horizontally layered VTI media

作　　者：魏建[1] 孙祥娥[1] WEI Jian;SUN Xiang’e(School of Electronics and Information,Yangtze University,J ingzhou,Hubei 434023,China)

机构地区：[1]长江大学电子信息学院,湖北荆州434023

出　　处：《石油地球物理勘探》2023年第4期812-817,共6页Oil Geophysical Prospecting

基　　金：大庆油田有限责任公司勘探开发研究院项目“井中VSP地震资料保真处理技术流程及质控方法研究”(DQYT‑1201002‑2018‑JS‑647)资助。

摘　　要：基于泰勒级数的P波旅行时方程的计算精度受到具有垂直对称轴的横向各向同性(Transverse Isotropy Medium with Vertical Symmetry Axis,VTI)介质的影响,为了改善这种情况,提出一种基于平方处理与系数匹配的计算方法。首先,利用平方处理将非平方形式的基于泰勒级数的旅行时公式转换为包含高阶项的平方形式;再使用系数匹配法处理旅行时平方公式的高阶项,保持方程炮检距的最高阶为常用的4阶;然后,在简化参数形式与优化旅行时平方公式计算的基础上,得到与各向异性参数相关的新系数y;最后,形成了含有y的基于平方处理与系数匹配的4阶P波旅行时计算方法。基于水平层状VTI介质模型的实验结果表明,与有理近似算法、三射线广义时差近似计算法和扩展广义时差计算法相比,该方法计算误差更小,同时远炮检距处的计算能力得到一定提高,从而给以旅行时方程为基础的应用提供了更多选择。The calculation accuracy of P‑wave traveltime equations based on the Taylor series is affected by the transverse isotropy medium with vertical symmetry axis(VTI).In order to improve this situation,a calculation method based on square processing and coefficient matching is proposed.In this method,the square processing is used to transform the traveltime equation of the non‑square form based on the Taylor series into the square form containing high‑order terms,and then the coefficient matching method is used to deal with the high‑order terms of the traveltime square equation so that the highest order of the equation offset is the commonly used fourth order.Then,on the basis of simplifying the form of parameters and optimizing the traveltime square equation,a new coefficient y,which is related to the anisotropic parameter,is obtained.Finally,a fourth‑order P‑wave traveltime calculation method with y based on square processing and coefficient matching is formed.The experimental results based on the horizontally layered VTI medium model show that compared with the rational approximation method,the generalized moveout approximation method based on three rays,and the extended generalized moveout approximation method,this method has smaller errors,and the calculation ability at the far offset is improved to some extent,which provides more options for the applications based on traveltime equations.

关 键 词：系数匹配 平方处理 旅行时 泰勒级数 非均质性参数 

分 类 号：P631[天文地球—地质矿产勘探]