Modeling of Coated Thin Wires in Layered Media for Subsurface Sensing and Communication

In this study we proposed an efficient coated thin wire model for simulations of electromagnetic telemetry system and energized casing in deviated and horizontal wells for subsurface sensing and communication. The steel drillstring acts as an antenna that may be treated as a thin wire excited by a gap voltage source located near the drill bit. The steel casing energized by electric sources can also be modeled as thin wire. The numerical model employs the electric field integral equation (EFIE) and the method of moments (MoM) to obtain a linear system for the axial current distribution on the drill string, which is subdivided into one-dimensional segments. By using the thin wire kernel, near-field interactions can be evaluated accurately and efficiently, while also reducing problem dimensionality and singularity order of the homogeneous medium contribution to the layered media Green's function (LMGF). The mud surrounding the pipe is modeled as coating which can be simplified to specific volume and surface current using quasi-static approximation. Numerical results are presented to verify the proposed approach to acquire fast solutions of coated thin wire in layered medium.