A telegrapher equation for electric - telemetering in drill strings

A reliable method of transmitting downhole information to the surface while drilling is essential to improve drilling applications. We have designed a numerical algorithm for simulation of electric-signal transmission through the drill string, based on the telegrapher equation (a circuit model). The drill string is then represented by a transmission line with varying geometrical and electromagnetic properties versus depth, depending on the characteristics of the drill string/formation system. These properties are implicitly modeled by the series impedance and the shunt admittance of the transmission line. The telegrapher equation is solved in the high-frequency range by using a direct method.