山前砾石区表层HTI介质速度各向异性建模方法  

A Method of Anisotropic Velocity Modeling for HTI Medium in the Surface of Piedmont Gravel Zone

作　　者：孔凡勇 谢安 夏建军 张录录 王利业 王伟[2] 于金林 韦建波 KONG Fanyong;XIE An;XIA Jianjun;ZHANG Lulu;WANG Liye;WANG Wei;YU Jinlin;WEI Jianbo(CNPC BGP,Xinjiang Geophysical Prospecting Department,Urumqi,Xinjiang 830016,China;CNPC BGP,Urumqi Branch of Research Institute of Geology,Urumqi,Xinjiang 830016,China;Xinjiang Research Institute,Huairou Laboratory,Urumqi 830000,China)

机构地区：[1]中国石油东方地球物理公司新疆物探处,乌鲁木齐830016 [2]中国石油东方地球物理公司东方物探公司研究院乌鲁木齐分院,乌鲁木齐830016 [3]怀柔实验室新疆研究院,乌鲁木齐830000

出　　处：《新疆石油地质》2024年第5期604-610,共7页Xinjiang Petroleum Geology

基　　金：东方地球物理勘探有限责任公司科研项目(03-01-07-2022)。

摘　　要：中国西部山前带表层普遍发育巨厚砾石沉积的冲积扇,这些冲积扇存在较强的方位各向异性,层析反演模型与垂向速度相差较大,导致三维资料静校正量计算精度和叠前深度偏移的中—浅层成像均受到较大影响。基于HTI介质理论,提出初至正演确定对称轴和分方位层析拟合建立各向异性模型的方法。首先通过各向异性调查微测井的表层结构正演初至时间和实际资料的初至时间对比确定各向异性对称轴特征,再对分方位初至层析反演模型进行椭圆拟合,求取初始快速度、慢速度和对称轴方位,使用二维VTI各向异性正演模拟和层析反演,求取对称轴方向速度的校正系数校正对称轴方位速度,进而建立山前砾石覆盖区的各向异性模型。There are widespread alluvial fans with extremely thick gravel deposits in the surface of the piedmont zones in western China.These fans exhibit strong azimuth anisotropy.The tomographic inversion velocity differs greatly from the vertical velocity,severely impacting the accuracy of static correction value of 3D seismic data and the imaging of shallow⁃tomedium layer in pre⁃stack depth migration.Based on the HTI medium theory,a method for determining the symmetry axis and constructing an anisotropic model through azimuthal to⁃mography fitting using first⁃arrival forward modeling was proposed.First,based on anisotropy,the first⁃arrival time from both micro⁃logging forward modeling and actual data is examined and compared to identify the symmetry axis characteristics.Then,elliptical fitting is performed on the azimuthal first⁃arrival tomography inversion model to derive the initial fast and slow velocities and the symmetry axis orientation.Next,by using 2D VTI anisotropic forward modeling and tomography inversion,the correction coefficients of the velocity in the direction of the symmetry axis are obtained.Finally,an anisotropic velocity model is established for the piedmont gravel zone.

关 键 词：山前带 近地表 各向异性 分方位层析 正演模拟 建模方法 

分 类 号：P631.4[天文地球—地质矿产勘探]