Characterization of EM downhole-to-surface communication links

A downhole-to-surface communication channel consisting of a long vertical cylinder (the stem) and an isolated downhole in-line cylinder (the electrode) embedded in a homogeneous earth is considered in this work. A signal voltage is applied between the electrode and stem, and the received voltage is picked up at the surface between the stem and a ground point or between two ground points. The analysis includes consideration of conductor longitudinal and surface impedance, joint resistance, voltage source resistance, and earth propagation effects to provide a realistic model for assessing the performance of the communication channel for measurement-while-drilling, drill stem testing, and production testing in oil and gas industry applications. Simulation results indicate that consideration of all of these effects is imperative for satisfactory modeling.