The artificial lift system selected to produce the Jubarte Field uses high-power and high-flow-rate subsea electrical submersible pump (ESP) systems with gas lift as a contingency in case of the need for ESP replacement. The gas lift mandrels are installed in the production well completion. The ESP systems are rated for 1,500 hp at full load and were deployed inside caissons constructed on the seabed, located 210 m downstream of the main production wellhead. The integrated unit is called a pumping module or módulo de bombeio (MOBO) in Portuguese.
Industry perception of average ESP run time, high replacement costs associated with intervention of the subsea ESP systems, and the limited track record available for comparable systems at the time of field development required a comprehensive approach to improve on system reliability from the beginning. The use of advanced technologies to extend the traditional concept of industrial process control to the management of the MOBO systems allowed continuous monitoring of ESPs to maintain operation within the design envelope.
The development of a complete "ESP culture" became a key element connecting the different teams involved in the operation. This required new procedures to be developed, new monitoring and surveillance teams introduced, and, most of all, management of change practices introduced to avoid issues related to the rotation of personnel involved in the operation of the ESP and related systems. The synergies created allowed the provision of timely solutions to face the challenges across the complete production system.
The gap study conducted at the beginning of the Jubarte ESP development identified many barriers and conditions preventing increased system reliability and affecting economic viability of such a large-scale project. This paper builds on such analysis using the operational data gathered during the 8 years of ESP operation, shows improvement in mean time to failure during the period, presents typical failures encountered in equipment and processes, introduces the de-risking process followed to strengthen the system, and provides the reasons behind the enhancements made.
Explanation of the measures proposed to significantly improve the reliability of these 1500-hp subsea ESP systems and the reasoning behind the enhancements will facilitate future projects of a similar nature.