首页|VTI介质改进声学近似qP波交错网格正演模拟

VTI介质改进声学近似qP波交错网格正演模拟

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Alkhalifah提出的声学假设近似令沿TI介质对称轴的qSV波速度近似为0,建立了相应的qP波波动方程并进行了数值模拟,但存在两个不足:一是方程中存在退化的qSV波解,不是纯qP波波动方程;二是方程不适用于ε＜δ(ε和δ为Thomsen参数)的介质.为此,在Liang等的工作基础上,将改进声学近似方法的思想引入qP波频散关系和一阶波动方程推导.令qSV波的精确频散关系中的圆频率为0,同时结合椭圆分解,推导了 VTI介质纯qP波解耦频散关系,利用改进标量算子的空间域渐近近似建立了 VTI介质改进声学近似qP波一阶速度—应力波动方程,采用交错网格有限差分算法实现了基于改进声学近似的VTI介质纯qP波正演模拟.频散关系分析和数值示例表明,基于改进声学近似的qP波一阶波动方程不包含退化qSV波,是纯qP波方程,与弹性波波动方程模拟结果吻合较好,具有较高精度,并且该方程在ε≥δ和ε＜δ的VTI介质中均是稳定的,同时也适用于复杂VTI介质.
Staggered-grid forward modeling of qP wave in VTI media with improved acoustic approximation
The acoustic approximation proposed by Alkhalifah assumed the qSV wave velocity along the sym-metry axis of the TI media to 0,and he established the corresponding qP wave equation and realized numerical simulations.However,there are two shortcomings.Firstly,there is a degenerate qSV wave solution in the equation,which is not a pure qP wave equation.Secondly,the equation is not applicable in media with ε＜δ(εand δ are the Thomsen parameter).Therefore,based on the work of Liang et al.,the idea of improved acous-tic approximation methods is introduced into the derivation of the dispersion relation and first-order wave equa-tions for qP wave.The circular frequency in the accurate dispersion relation of the qSV wave is set to 0,and the elliptic decomposition is used to derive the decoupled dispersion relation of pure qP waves in VTI media.The spatial asymptotic approximation of the improved scalar operator is adopted to establish the qP wave first-order velocity and stress wave equations in VTI media with improved acoustic approximation.The staggered grid finite difference algorithm is used to achieve the forward simulation of pure qP wave in VTI media based on improved acoustic approximation.The analysis of dispersion relation and numerical examples show that the qP wave first-order equation with improved acoustic approximation does not include degenerate qSV waves and is a pure qP wave equation,which is in good agreement with the simulation results of the elastic wave equation and has high accuracy.The equation is stable in VTI media with bothε≥δand ε＜δ and is applicable for complex VTI media.

improved acoustic approximationqP waveVTI mediadispersion relationstaggered gridspatial asymptotic approximation

梁锴、陈浩然、孙上饶、印兴耀

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中国石油大学(华东)地球科学与技术学院,山东青岛 266580

海洋国家实验室海洋矿产资源评价与探测技术功能实验室,山东青岛 266071

改进声学近似 qP波 VTI介质 频散关系 交错网格 空间域渐近近似

国家自然科学基金项目&&山东省自然科学基金项目中海油有限公司项目

4203010342074162ZR202111200174CNOOC-KJ GJHXJSGGYF 2022-01

2024

10.13810/j.cnki.issn.1000-7210.2024.01.010

石油地球物理勘探
东方地球物理勘探有限责任公司

石油地球物理勘探

CSTPCD北大核心
影响因子：1.766
ISSN：1000-7210
年,卷(期)：2024.59(1)
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