Development of a finite differential model for the analysis of environmental effects on transmission lines for down-hole applications

Abstract

Coaxial cables are often used for data-transmission between top-side and down-hole tools over long distances. In term of cost, it is advantageous to use the same cables for power transmission when feasible. However, environmental effects can degrade the performance of cables, which are exposed to hostile conditions. This paper examines the environmental effects on transmission efficiency of coaxial cables when used for the transmission of power to down-hole tools and data acquisition systems. The performance of the cables was analysed using a finite differential model. A special feature of the model is that it implicitly introduces the effects of temperature differentials to which the cable may be exposed, through the primary cable constants. The model can be used to predict the optimum condition for maximum power transfer in the low-to-medium frequency range.