摘要
瞬变电磁虚拟波场Born近似成像是通过Born近似对瞬变电磁虚拟波场方程进行线性化处理,求取速度扰动量实现成像的方法.Born近似采用半空间Green函数,在背景速度变化较大时成像分辨率较低.因此,本文从虚拟波场出发,建立辐射场与散射场满足的Helmholtz方程,导出层状介质Green函数表达式,将其应用于Born近似中,得到了基于层状介质格林函数的Born近似电导率计算公式和散射场关于速度扰动量的关系式,最终利用速度扰动量实现成像.通过对理论模型的实验计算,验证了利用层状模型Green函数的Born近似成像算法,能够重建地层电阻率分布,改善Born近似虚拟波动方程逆散射反演的垂向分辨率,获得较好的成像效果.对甘肃地区的实际资料处理结果表明,层状介质Green函数的Born近似,是一个精确度较高、稳定性好、有实际应用价值的成像方法.
In this study,the Born approximation imaging method of transient electromagnetic virtual wave fields is used to linearize the transient electromagnetic virtual wavefield equation through the Born approximation,after which the velocity disturbance is obtained,thereby achieving imaging.The Born approximation uses the half-space Green function,which results in low imaging resolution when the background velocity varies greatly.Starting from the virtual wave field,this paper establishes the Helmholtz equation satisfied by the radiation and the scattering fields,then derives the Green function expression of layered media,and applies it to the Born approximation.The calculation formula of Born approximation conductivity based on the Green function of layered medium and the expression of the velocity disturbance of the scattering field are obtained,and finally the velocity disturbance is used to achieve imaging.Through the experimental calculation of the theoretical model,it is verified that the Born approximation imaging algorithm using the Green function of the layered model can reconstruct the resistivity distribution of the stratum,improve the vertical resolution of the inverse scattering inversion of the Born approximation virtual wave equation,and obtain high-quality imaging.The results of the actual data processing in Gansu Province show that the Born approximation of the layered medium Green function is an imaging method that is quite accurate,stable and practical.
作者
马劼
李貅
戚志鹏
樊亚楠
李梓源
曹华科
MA Jie;LI Xiu;QI ZhiPeng;FAN YaNan;LI ZiYuan;CAO HuaKe(College of Geology Engineering and Geomatics,Chang′an University,Xi′an 710054,China;Integrated Geophysical Simulation Lab of Chang′an University(Key Laboratory of Chinese Geophysical Society),Xi′an 710054,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第6期2631-2645,共15页
Chinese Journal of Geophysics
基金
重点研发计划项目(2021YFB2600402)
国家自然科学基金项目(41830101),面上项目(42074168)
国家自然科学基金(41704108)联合资助。
关键词
瞬变电磁
虚拟波场
格林函数
Born近似成像
Transient electromagnetic
Virtual wave fields
Green function
Born approximation
