Designed for intervention-constrained offshore wells and difficult-to-access land wells, the high-reliability ESP system was developed with a holistic approach, integrating proven technologies that have been improved for greater performance. Each step of the process, from engineering design to manufacturing, field operation, installation and ongoing surveillance, was enhanced to meet the objectives of higher reliability and longer runlife.
Improved design, rigorous testing
The new system marks the culmination of an evolution that Schlumberger embarked on in 2008 to meet production demands in Brazil’s deepwater presalt Jubarte Field. The desire to replicate that early presalt success, taking all that was good about the project to industrialize the process so that it could be applied anywhere, led to this advance in artificial lift technology that compasses strict design, strong quality control manufacturing, flawless installation and full-time surveillance. The end result is a system that is expected to double average ESP runlife, eliminate unplanned workovers due to early failures, reduce nonproductive time (NPT) and optimize uptime with enhanced monitoring.
By coupling together the best technologies from the conventional ESP system with select technology from the subsea high-reliability ESP systems developed for the Jubarte Field and high-temperature systems used at 250 C (482 F), Schlumberger engineered a production system to significantly extend runlives in the offshore market.
Apache’s primary objectives were to achieve a longer ESP runlife and reduce early pump failures, thereby decreasing the need for intervention, including rig time and NPT. With less deferred oil production and the potential to eliminate 14 to 21 days per well of future workover rig time, the company would be better positioned to boost overall production efficiency. The initial goal to achieve 2 1/2 years runlife through incremental improvements was broadened with Apache’s selection of the high-reliability ESP system to deliver the significant step change of a four-year runlife.
The collaborative effort between Apache and Schlumberger included examining ESP failure modes from January 2009 to January 2014 to address those issues in engineering the new high-reliability ESP system. Analysis of those failures determined they occurred due to many factors, including rotor-bearing wear, motor failure, electrical winding, damaged O-ring, aging and cable failure. The engineering team targeted not only primary failure modes but also looked at other components that were starting to wear. The new high-reliability ESP system was designed to address those issues through engineering and manufacturing improvement.
The first deployment of the high-reliability ESP system commenced in April 2015 on an Apache platform in the long-producing Forties Field in the U.K. sector of the North Sea. At the time, Apache was running 57 ESP completions out of 110 active Forties Field wells, with 40% of the operator’s North Sea production coming from ESP lifted wells. The company’s strong usage of ESP for artificial lift made it an ideal candidate for installing several new ESP production systems, with the initial installation of four units.
Leveraging breakthroughs in technology developed for hostile environments, the high-reliability ESP system features robust components designed to resist abrasion, corrosion and temperature. Components are manufactured and tested in a dedicated environment using advanced processes and machinery. Equipment is assembled using a protocol that is fully traceable and audited to arrive free of defects to the well site. In a rigorous testing process, the system is subjected to frequency and operation range sweeps to mimic varying pumping regimes, with numerous starts and stops to stress bearings, shafts and compensation systems, ensuring the equipment can reliably withstand continuous field restarts and intermittent operation.