基于双程波方程走时的克希霍夫深度偏移技术  

Kirchhoff Depth Migration Technique Based on Two-way Wave Equation Traveltime

作　　者：张健男 李三福 张敏 王新领 Zhang Jiannan;Li Sanfu;Zhang Min;Wang Xinling(Top Data Center(Zhanjiang),Geophysical Division,China Oilfield Services Co.,Ltd.,Zhanjiang Guangdong 524057,China)

机构地区：[1]中海油田服务股份有限公司物探事业部特普数据中心(湛江),广东湛江524057

出　　处：《工程地球物理学报》2023年第4期500-508,共9页Chinese Journal of Engineering Geophysics

基　　金：中海油服科研项目(编号:WTB21YF009)。

摘　　要：传统克希霍夫偏移采用高频近似假设,难以适应复杂速度模型结构。在复杂速度结构工区,射线追踪方法存在焦散、阴影和多波至问题,走时场精度较低,偏移算子的振幅加权是走时场的函数,在折射盲区与模拟波场的振幅差异较大。本文实现了基于GPU的双程波方程克希霍夫偏移,首先利用双程波波动方程计算走时场和振幅场;然后采用振幅场对偏移算子进行加权,逐道偏移,最终输出成像道集。试验中采用GPU求解双程波方程来改善运算效率,利用坡印廷矢量进行上下行波分解,存储下行波最大振幅的走时场和振幅场。结果表明,本文实现的偏移算子脉冲响应不存在偏移阴影区域,成像剖面在盐丘下部信噪比和同相轴连续性明显优于传统克希霍夫方法。本文研究的方法改进了克希霍夫偏移的成像质量,保持了传统克希霍夫高频率、高效率、灵活输出各种道集的优势,具有较高的实用价值。Travel time field calculation is the core problem of Kirchhoff depth migration.The traditional Kirchhoff migration adopts the assumption of high frequency approximation,which is difficult to adapt to the complex velocity model structure.With the wide application of full waveform inversion technology,the resolution of the velocity model and the strong lateral variation have been significantly improved.In the complex velocity field,the ray tracing method has caustics,shadows,multi-wave arrival problems,and the accuracy of the traveltime field is low.In this paper,the two-way wave equation Kirchhoff migration based on GPU is realized.First,the two-way wave equation is used to calculate the travel time field and amplitude field.Secondly,the amplitude field is used to weight the migration operator,migrate each channel,and finally output the imaging trace set.In this experiment,GPU was used to solve the two-way wave equation to improve computational efficiency,and Poynting vector was used for decomposing up and down traveling waves,storing the travel time field and amplitude field of the maximum amplitude of the downward traveling wave.The results show that the pulse response of the migration operator implemented in this paper does not have a migration shadow area,and the imaging profile has significantly better signal-to-noise ratio and continuity of the same phase axis in the lower part of the salt dome than the traditional Kirchhoff method.This method improves the imaging quality of Kirchhoff migration,maintaining the advantages of traditional Kirchhoff high frequency,high efficiency,and flexible output of various gathers,and has high practical value.

关 键 词：双程波方程 走时计算 克希霍夫偏移 盐下成像 

分 类 号：P631.4[天文地球—地质矿产勘探]