An efficient, accurate numerical modeling scheme has been developed, based on the integral equation solution to compute electromagnetic (EM) responses of thin sheets over a wide frequency band. The thin-sheet approach is useful for simulating the EM response of a fracture system in the earth. The focus of this development has been the accuracy of the numerical solution over a wide-band frequency range of up to 100 MHz. The effect of displacement currents is included to correctly evaluate high-frequency EM scattering.
Currently, EM responses of two thin sheets with different geometrical and electrical properties embedded in a three-layer earth can be modeled over a frequency band of 10−3 to 108 Hz. The layered earth and the sheets can be electrically dispersive, an important feature that allows analysis of frequency-dependent characteristics of the model under investigation. The source field can be generated by a remote or local electric or magnetic dipole located on the surface or in a borehole. A plane-wave source can also be used, and numerical analyses have been made for magnetotellurics and the high-frequency impedance method.