摘要
采用 Gaver-Stehfest( G-S)方法模拟水平电偶极源在不同介质模型中地表面的负阶跃波电磁场响应 ,然后引入逆时序偏移的观点 ,把这些电磁场响应作为实际观测值 ,利用 Stratton-Chu积分公式将其向下偏移 ,对偏移后的电磁场值进行归一化处理并对场值求偏导数 ,重建地下拟地震深度剖面图 ,实现时间域电磁场的偏移成像。选用了均匀介质、含良导和高阻薄层水平均匀层状介质模型以及高阻柱体、断层等模型分别进行计算 ,成像的结果表明能够得到较高质量的地下地电构造图 ,从重建的深度剖面图中可以识别出地下反射界面的位置 ,该图比时间剖面直观。
In this thesis,the transientelectromagnetic responseson the surface for differentgiven modelsunder the txcitation of a grounded dipole are calculated by using the Gaver- Stehfest( G- S) method,then the authors introduce the concept of reverse- time migration,use Stratton- Chu integral formulas to migrate downward these forward modelling results being used as measured electromagnetic field,and then normalize anddifferentiate the migrated electromagnetic field,reconstruct the pseudo- seismic depth profile,realize the migration and imaging of time- domain electromagnetic field.To testthe migration and imaging method,one homogeneous medium and two layered mediums including a high conductivity orhigh resistivity thin layerare selected for calculating respectively. From the calculation results we can obtain the quality subsurface geoelectric structure map and the locations of reflectors which are better than those in time profile.
出处
《现代地质》
CAS
CSCD
北大核心
1999年第4期455-460,共6页
Geoscience
基金
国家自然科学基金!资助项目 (项目号 :494742 19)成果
关键词
时间域
电磁场
偏移成像
S-C积分
time- domain electromagnetic field,migrating and imaging,Stratton- Chu integrate,normalize
