Estimation of temperature effects on wells with artificial lift by Electric Submersible Pump (ESP) is necessary because heat transfer may interfere with fluid characteristics, motor behavior, cables and pump, affecting the whole system. This work presents and describes a computational model of heat transfer in ESP systems for multiphase flow in deviated wells.
The methodology adopted in this work considered geothermal gradient and the heat transfer between motor and production fluids. The geothermal gradient represents how temperature increases inside the well as the true vertical depth increases. For deviated wells, the well is divided by sections and temperature increase at each section is calculated as a function of its true vertical depth and the geothermal gradient. In the transfer of heat between motor and production fluids, calculated changes in motor and fluid temperature occur mostly by forced convection on account of high flow rates available in this artificial lift method.
The computational model was implemented in a program developed to simulate ESP system behavior. To validate developed modeling, results obtained through simulation of vertical wells were compared with field data obtained from wells equipped with bottom-hole sensors. These comparisons showed that calculated temperature values were similar to those obtained from a field data, implying satisfactory results. Deviated wells with ESP system were simulated and the results were also evaluated. Therefore, through analysis of the obtained results for thermal calculation in ESP systems, it is possible to verify if the equipment are working according to their specification, especially those related to the electrical system such as cable and motor.
In order to increase the ESP system efficiency, the results obtained through this work are useful for the development of studies focused on reducing harmful effects caused by the high temperatures present in this artificial lift method.