井中磁源瞬变电磁三维时域有限差分数值模拟

3D FDTD numerical simulation for transient electromagnetic of magnetic source in borehole

应用时域有限差分法,采用显式差分方程,选取磁偶极子源作为初始条件和不同阶Mur吸收边界条件,对包含低阻异常体的均质全空间中磁偶源产生的瞬态场进行三维数值模拟,模拟计算井中磁源瞬变电磁场传播以及井旁三维低阻异常体的响应情况,简要分析特征规律。研究结果表明:时域差分法可在一定条件下保证正演模拟的精度和效果;场源激发条件和异常体情况不同,响应特征差异较大。

Finite-difference time-domain method was used to simulate three-dimensional transient electromagnetic field in the uniform whole space with conductive thin plate by using magnetic dipole source as initial condition and Mur absorbing boundary condition. Diffusion of transient electromagnetic field for BHTEM and response characteristics for conductive plate beside horehole was simulated. The characteristics and regularity were analyzed based on numerical simulations in different conditions. The result shows that finite-difference time-domain method can ensure the accuracy and effectiveness of forward modeling for certain conditions, and the BHTEM response characteristics are very different in different source conditions and target bodies.