Effective Calculation of EM Green’s Functions Applied to MCSEM Forward Modelling

In this paper, we present an algorithm for calculating Green’s functions and EM fields for a dipole transmitting source embedded in a layered homogeneous earth. We first set up a fictitious interface through the source parallel to layer boundaries. The EM potentials are continued upward and downward from the interface with continuity conditions, where the reflection coefficients are derived from the accumulated impedances or conductances. The source coupling is treated as a jump of boundary conditions at the fictitious interface. In this way, the source term in the mathematical formulation is separated from the propagation terms. This generalizes the algorithm for any form of electrical and magnetic transmitting dipole sources and simplifies the mathematical formulation and programming. We demonstrate the effectiveness of the technique by considering a horizontal electrical dipole as transmitter for marine CSEM forward modeling.