Computation of eddy-current density on ESP motor and well casings under different operating conditions

Abstract

This paper presents a 2D finite-element analysis of the induced eddy currents on motor and oil well casings of an electrical submersible pump (ESP) oil lifting system. Simulation results revealed that the increase in motor-casing conductivity and/or permeability decreases the eddy-current density on the well casing, contrary to that on the motor casing. Further increase in one or both of these parameters leads to a decrease in both current densities as a result of the skin effect phenomenon. However, the increase of well casing conductivity and/or permeability increases the eddy-current density on the well casing, while that on the motor casing remains unchanged. Increasing the fluid-mixture conductivity does not have any effect on the eddy-current density on the well casing, and for further increase in the fluid conductivity it decreases drastically, contrary to that on the motor casing which remains constant. The higher the current imbalance (including single phasing) and/or motor eccentricity, the higher is the maximum eddy-current density. Consequently, the increase of eddy-current density leads to an increase of the motor and well casings’ temperature, where the latter is known to accelerate the corrosion rate. It can be concluded that the design parameters and the construction of the motor and well casings play an important role in their corrosion.