Shrouded Y-Tool Application for Optimum ESP System Run Life

Abstract

It is critical to manage the temperature rise seen in the electrical power system and submersible motor, in order to have an optimum Electrical Submersible Pump (ESP) run life. This paper presents a case study in which a solution was applied to better manage the heat rise seen in the ESP during operations, particularly in low flow applications, that has led to a measurable increase in ESP run life across the field. A Middle Eastern Operator of ESPs had installed wells completed with Y-tools and ESPs that showed unusually high motor temperatures and shorter than expected system run lives. A study was conducted, and the remedial action implemented was to install a shroud around the Y-tool, reducing the flow space in the annulus thus increasing the velocity of fluid past the motor. The study compared the data gathered from the shrouded and non- shrouded Y-tool ESP installations to determine the effectiveness of the corrective actions. Motor temperature is a function of bottom hole temperature, percentage load against nameplate, fluid properties, power quality and fluid velocity past the ESP motor. This study has shown that the shrouded ESP significantly increased the fluid bypass velocity (more than 1ft/sec) alongside the submersible motor to deliver the required cooling for stable, reliable operation. Unshrouded systems experienced higher motor and intake temperatures that is instrumental in the deterioration in the insulative properties of the electrical system and leads to greater current leakage with the passage of time. This paper will provide full, detailed knowledge on shrouded Y-Tool systems that can be effectively applied for low flow rate production, allowing well bore full access for wireline or coil tubing jobs. Moreover, efficient motor cooling is provided by the higher fluid velocity and while providing a better pump performance, is expected to result positively in ESP run life.