Pseudoanalytical Formulations for Modeling the Effect of an Insulating Layer in Electromagnetic Well Logging

In this paper, we present a set of compact formulations to model the response of the electromagnetic well-logging tools in eccentric multilayered medium. Different from previous models, the coil antennas are imbedded in an insulating protection layer (IPL) rather than expose to the borehole directly, which agrees much better with some real tools, e.g., the array induction logging tool. The effects of both metal mandrel and an IPL are considered in eccentric scenarios. Our formulations are derived on the basis of the ratios of cylindrical functions, which obviate the notorious overflow issues during numerical computation. Numerical results show that the effect of IPL gradually appears with the increase of the eccentric distance.