Electrical Submersible Pumps (ESP) are commonly employed in brownfield wells where watercut has increased and gas lift is no longer an efficient production strategy. Much attention is rightly paid to the impact this strategy will have on the reservoir and careful planning is given to the workover operation. However, often the challenge of implementing ESPs is not below the wellhead, but at the facilities level.
One such example is the Bokor Field offshore Sarawak where, in 2008, the first production ESPs in Malaysia were installed. Initially, an in-depth power study was performed. A holistic plan was then developed to distribute the available power to the ESPs via the existing electrical infrastructure. Various locations were considered for the placement of ESP control equipment and ultimately the project team chose a location near to the wellheads. This choice of location required less structural re-design but did involve laying a subsea cable for power transmission and consideration of IP Area Classification Codes for Installations Handling Flammable Fluids.
The ESP power and control equipment was installed inside a customized Local Electrical Room (LER) and, because of space constraints, small deck extensions were required. Safety systems such as fire and gas detectors and individual well sensors for downhole status and flowline pressure monitoring were also included. The electrical systems were tied into the wellhead control panel to allow for automatic process and emergency shutdown actuation. Finally, the surveillance system needed upgrading to incorporate these sensors and allow remote operation since the object platforms were to remain unmanned.
For the Bokor field, the preparation of facilities for ESPs ultimately became its own project much larger and more complex than the workovers themselves. A field designed for gas lift with minimal power needs was successfully transformed to increase and efficiently distribute power along with allowing safe, remote pump operation and surveillance.