VFD Switchboard Replacement for Downhole Pumps on Eni Douglas Oil Platform
VFD Switchboard Replacement for Downhole Pumps — Delivered in a Shutdown Window
Project Overview
VFD Switchboard Replacement for Downhole Pumps on Eni Douglas Oil Platform
Turnkey replacement of the VFD switchboard and sine filters during a planned shutdown, improving reliability and operational resilience.
The Douglas platform sits in the Irish Sea, fifteen miles off the coast of North Wales, operated by Eni. Its downhole pumps are driven through variable frequency drives, and the switchboard supplying them is production equipment: when it is out, the wells it serves are not producing.
ABB awarded MJR Power & Automation the contract to deliver the electrical infrastructure upgrade. The scope was the complete removal and replacement of VFD Switchboard B, together with the installation of four external sine filter cabinets with their associated air and seawater cooling systems; work critical to the downhole pump switchboard upgrade and intended to improve electrical reliability and long-term operational resilience.
It was delivered during a planned shutdown, with strict time and safety constraints, alongside multiple other contractors working the same window. Complex logistics, offshore mobilisation and a confined switchroom added to the difficulty.
Project significance A platform shutdown is the most expensive time in an operator's calendar. Production stops, the accommodation fills with contractors, and every scope on the window is competing for the same access, the same lifts and the same isolations. Work either finishes inside the window or it becomes the reason the platform does not restart. There is no version of this job that runs long.
The challenge
A planned shutdown that could not overrun.
The complete scope, decommissioning, removal, installation, integration, testing and reinstatement, had to be finished inside the shutdown window. Overrunning delays the restart of a producing asset.
A confined switchroom.
Extracting a switchboard and installing its replacement in a space designed to hold one, not two, with no room to stage equipment and no straightforward route in or out.
Offshore mobilisation and logistics.
Every panel, cabinet, tool and consumable had to be shipped or flown to a platform fifteen miles offshore, in the right order, to arrive when the window allowed. Nothing can be collected from a merchant if it is missing.
Cabinets that did not fit through the route to their location.
Positioning the four external sine filter cabinets on the cellar deck required stair treads and scaffold barriers to be removed to get them into place. A physical logistics problem before it was an installation one.
Multiple contractors, one window.
Several specialist contractors were working the same shutdown, so MJR Power & Automation's scope had to be coordinated around theirs for access, isolations and sequencing.
Safety-critical circuits to reinstate.
Emergency shutdown, current transformer and inter-trip circuits all had to be removed and reinstated correctly. These are the circuits that stop the platform safely and getting them wrong is not a commissioning issue.
Scope of Work
Turnkey Electrical and Mechanical Upgrade Package
Switchboard replacement:
- Decommissioning — isolation and removal of legacy power, control and ESD cables; dismantling and extraction of the existing Switchboard B panels
- Installation — new switchboard plinths; positioning and assembly of the new Switchboard B; busbar connections; cable installation between transformers, sine filters and switchboards
- Integration — reinstatement of ESD, CT and inter-trip circuits; control panel modifications; installation of cubicle lighting and auxiliary systems
- Testing and commissioning support — Megger and continuity testing of power and control cables, ductor testing of busbars, termination of power cable ends
- Full reinstatement of fireproofing and HVAC systems
Sine filter installation — four external cabinets on the cellar deck:
- Positioning and fixing — allocation of each filter to its designated deck location using pre-drilled stainless-steel skids and drilling templates, including removal of stair treads and scaffold barriers to move cabinets into position
- Mechanical assembly — fixing cabinets to the deck with Hollo-Bolts, neoprene strips and insulated shoulder washers to prevent galvanic corrosion
- Installation of cooling ductwork and seawater cooler units, aligned with future pipework connections
Solutions Delivered
The Removal — Taking out what was there
Legacy power, control and ESD cables were isolated and removed, and the existing Switchboard B panels dismantled and extracted from the switchroom. On a confined offshore switchroom, this is a substantial job in its own right and it has to be complete before any of the new equipment can go in.
The Installation — New board, new plinths, new connections
New switchboard plinths were installed, the new Switchboard B positioned and assembled, busbar connections made, and cabling installed between the transformers, the sine filters and the switchboards.
The Sine Filters — Why they are there
Four external sine filter cabinets were installed on the cellar deck with air and seawater cooling.\
Sine filters smooth the output of a variable frequency drive into something closer to a true sine wave. That matters most when the cable run between the drive and the motor is long — and on a downhole pump the motor is at the bottom of a well, with a great deal of cable between it and the drive. Without filtering, the switching waveform produces voltage reflections and insulation stress at the motor end, which shortens the life of a pump that cannot be reached without a workover.
The Mechanical Work — Fixings that will not corrode
Each cabinet was allocated to its deck location using pre-drilled stainless steel skids and drilling templates, then fixed with Hollo-Bolts, neoprene strips and insulated shoulder washers to prevent galvanic corrosion between dissimilar metals. A detail that determines whether a stainless cabinet bolted to a steel deck is still sound in ten years' offshore weather.
Cooling ductwork and seawater cooler units were installed and aligned with future pipework connections.
The Integration and Reinstatement — Putting the platform back
ESD, CT and inter-trip circuits were reinstated, control panels modified, and cubicle lighting and auxiliary systems installed. Power and control cables were Megger and continuity tested, busbars ductor tested, and power cable ends terminated.
Fireproofing and HVAC systems were fully reinstated — the part of a shutdown scope that is easy to overlook and impossible to omit, because the platform cannot restart without them.
Delivery & Approval
Completed Inside the Window, Safely
MJR Power & Automation delivered the complete electrical and mechanical upgrade package, both the switchboard replacement for downhole pump operations and the sine filter installation, within the planned shutdown window.
The project was delivered safely and in compliance with offshore HSE standards, with close collaboration between Eni, ABB and other specialist third-party contractors.
Technical Summary
- Operator Eni
- Awarded by ABB
- Asset Douglas platform — fixed offshore installation
- Location Irish Sea, 15 miles off the North Wales coast
- Sector Oil & Gas / Offshore Platforms
- Application Variable frequency drives for downhole pumps
- Main scope Complete removal and replacement of VFD Switchboard B
- Additional scope Four external sine filter cabinets with air and seawater cooling
- Safety circuits ESD, CT and inter-trip circuits removed and reinstated
- Testing Megger and continuity testing; ductor testing of busbars
- Reinstatement Fireproofing and HVAC systems fully reinstated
- Mechanical Stainless steel skids, Hollo-Bolts, neoprene strips, insulated shoulder washers
- Delivery Within a planned shutdown window
- Working environment Confined switchroom; offshore mobilisation; multiple concurrent contractors
Project Outcomes
Delivered inside the shutdown window.
Both the switchboard replacement and the sine filter installation completed within the planned window, so the platform's restart was not delayed by the electrical scope.
Improved reliability for downhole pump operations.
A new switchboard and sine filtering supporting the drives that run the platform's production pumps.
Improved maintainability.
The platform's electrical distribution network is more maintainable than the arrangement it replaced, which matters on an asset where every intervention is an offshore mobilisation.
Delivered safely to offshore HSE standards.
On a live shutdown alongside multiple other contractors.
Long-term operational integrity.
The stated purpose of the upgrade was resilience rather than capability — keeping a mature asset producing reliably.
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