Comprehensive Model of Heat Transfer between ESP Motor and Multiphase Fluid Included Solid Phase

Abstract

This work is devoted to developing of comprehensive mechanistic model of heat transfer between an ESP motor and multiphase fluid. The model takes into account not only such parameters as flow pattern, gas/oil ratio, flow regime, etc. but also solid phase. Solid phase was included based on modern experimental investigations in the area of heat transfer in multiphase systems containing solid phase and flowing in annuli. The developed model was verified by means of temperature data taken using telemetry system during steady-state production from the wells with ESPs. Based on the model sensitivity analysis for the change of such parameters as solid size, solid phase concentration, and motor shroud size was performed. Impact of each parameter on motor cooling is discussed. It is shown that optimization of motor shroud size can lead to significant heat transfer enhancement between the ESP motor and solid-liquid mixture as compared to heat transfer between the ESP motor and liquid. This effect is achieved due to solid particles which have sufficient freedom in bombarding motor wall so that they thin viscous boundary layer. However, if the motor shroud size selection is inconsistent to the given solid phase concentration and solid particle size, this can cause deterioration of thermodynamic conditions for motor cooling.