Increased production uptime, extending electric submersible pump (ESP) run life, and decreasing workover costs are critical for well profitability. ESP applications in the North Sea face the challenge of remote access where workover costs are high and rig availability is limited, coupled with sand production and relatively high bottomhole temperatures. Several developments have been made to ESP manufacture that overcome these obstacles, and field examples have shown the benefits from this new type of high-tier ESP.
To achieve a high-reliability system, all aspects of the ESP lifecycle were studied and updated. Run-life metrics from ESPs run in the North Sea were reviewed, which included a failure mode analysis from dismantle inspections of pulled ESPs. Based on this research, both critical and noncritical components identified as affecting ESP run life were upgraded from the best features and premium technologies available. Selected technologies currently used on steam-assisted gravity drainage (SAGD), high-horsepower subsea, abrasive, and unconventional applications were integrated into a single qualified system. The resulting ESP system was built and tested inside a new purposely built, state-of-the-art facility dedicated to premium ESP equipment of this type. New processes and controls ensure zero-defect manufacturing and increased quality when compared to the standard mass-produced ESPs of the industry. Each ESP was tested as a string for 72 hr before shipping. Enhanced transportation in the form of special shipping boxes was also implemented.
Eight complete systems were delivered to the North Sea in 2015, six of which are already installed. Improved procedures including aviation-style checklists and special tools were developed specifically for the installation of the units. The systems deployed in the North Sea are operating without failures with a cumulative run life more than 2,170 days. Special surveillance and dedicated procedures in monitoring the system aim to extend systems' run life to more than 4 years.
The increase in quality applied during design, manufacturing, transportation, and deployment of the systems had never been seen in the ESP market before. The systems deployed in the North Sea represent the first step of the next generation of ESPs, which will enable a departure from the traditional commodity applications and deliver high-reliability systems.