倾斜正交各向异性介质中多次反射qP波射线追踪  

Seismic ray tracing for multiple reflected qP wave in tilted orthorhombic anisotropic media

作　　者：王迪 吴翔 白超英[1,2,3] 李兴旺 WANG Di;WU Xiang;BAI Chaoying;LI Xingwang(School of Geological Engineering and Geomatics,Chang’an University,Xi’an,Shaanxi 710054,China;Institute of Computing Geophysics,Chang’an University,Xi’an,Shaanxi 710054,China;National Engineering Research Center of Offshore Oil and Gas Exploration,Beijing100028,China)

机构地区：[1]长安大学地质工程与测绘学院地球物理系,陕西西安710054 [2]长安大学计算地球物理研究所,陕西西安710054 [3]海洋油气勘探国家工程研究中心,北京100028

出　　处：《石油地球物理勘探》2023年第3期632-640,共9页Oil Geophysical Prospecting

基　　金：国家自然科学基金重点项目“多辐射源、多分辨地空瞬变电磁深部探测偏移成像理论与方法研究”(41830101);陕西省自然科学基金项目“菲涅尔体射线精细成像研究”(2021JQ-245)联合资助。

摘　　要：实际地层中常发育裂隙,表现出正交各向异性介质特征。为研究此类复杂介质中qP波的传播规律以及计算旅行时和射线路径,首先从Christoffel方程出发讨论了正交各向异性介质中qP波相速度和群速度的计算方法,并利用旋转矩阵求得倾斜正交各向异性介质的群速度分布,然后结合分区多步改进型最短路径算法,实现了在倾斜正交各向异性介质中追踪直达、反射和多次反射qP波。求取群速度分布时,引入了球面三角剖分算法确定近似均匀分布的相速度方向采样点,能够节省约一半的计算量;此外采用GPU并行计算技术可进一步提高计算效率。数值模拟结果表明,该算法旅行时计算相对误差不超过0.35%,具有较高的稳定性和计算精度,可应用于追踪复杂的多次波;效率分析结果显示,求取群速度分布是较为耗时的过程,串行程序中该过程约占总耗时的61%,采用GPU并行计算后,计算效率提高了近30倍。Due to the existence of fractures,the orthorhombic anisotropic characteristics are often observed in actual strata.To determine the traveltime and ray paths of qP wave in orthorhombic anisotropic media,this paper firstly calculates the phase and group velocities of qP wave based on Christoffel equation,and the group velocity distribution of the tilted orthorhombic media is obtained by using rotation matrix.Then based on the multistage scheme incorporating the modified shortest-path method,an algorithm for tracing multiples in the tilted orthorhombic media is proposed.The computational amount for calculating the group velocity distribution can be saved to about half by introducing the spherical triangulation algorithm to determine the sampling points of phase direction which are approximately uniformly distributed.In addition,GPU parallel computing technology can further improve computational efficiency.This algorithm can be applied to direct,reflected,and multiple reflected waves,and the traveltime calculation relative error does not exceed 0.35%.The results of efficiency analysis show that the calculation of the group velocity distribution is time-consuming,which accounts for about 61%of the total time in the serial program.With the GPU parallel technology,the computing efficiency has been improved by nearly 30times.

关 键 词：倾斜正交各向异性 分区多步 改进型最短路径算法 地震射线追踪 

分 类 号：P631[天文地球—地质矿产勘探]