With many of the world’s 12,000 offshore oil and gas platforms approaching end of field life, the decommissioning sector is increasing in prominence. In fact, it’s already valued at US$6.97 billion annually and growing at more than 9% a year.^[1] 

But, with decommissioning, it’s never a simple matter of shutting a facility and removing its remnants. After production ceases, comes the meticulous process of preparing the asset for removal. Then, typically, it will lie in limbo for several months, possibly years -  no longer operational, but not yet gone. 

This in-between phase is called lighthouse mode. And Petrofac has many years’ experience of planning for it, managing it, and ensuring it’s made as safe, predictable, and cost-effective as possible. 

WHY LIGHTHOUSE MODE?

In an ideal world, an asset would move seamlessly from one phase of decommissioning to the next, culminating in the timely arrival of a heavy lift vessel to remove what’s left of the facility and transport it back to shore to be dismantled and recycled. But, with vessel availability, budget constraints and weather windows to consider, removal is rarely immediate.  

So, following an intense period of preparation, activity comes to a near standstill. However, the asset is not abandoned. Instead, typically, it’s put into lighthouse mode, a transitional phase, where the operator continues to maintain asset integrity, ensures environmental safety, and meets regulatory obligations, but does so via a lower-cost operational state. You could say it’s the oil and gas equivalent of a medically induced coma -  the asset is immobile and unconscious, yet its vital signs are closely monitored. 

With decades of experience in asset decommissioning, Petrofac understands the significance of planning and managing this unique phase. 

“As a long-term partner to assets globally, we’ve acted as duty holder and outsourced operator from production through to decommissioning,” says Ross Sutherland, Operations Director, Global Technical Solutions.  

“We help clients transition into, through, and out of lighthouse mode in a way that’s safe, cost-effective, and regionally compliant.” 

PREPARING FOR LIGHTHOUSE MODE

Planning is key. A series of critical stages must take place to ensure the asset is safely and efficiently prepared for the final stages of decommissioning.  

Firstly, well decommissioning, a safety-critical operation involving the permanent isolation of the asset from hydrocarbon-bearing formations. At Petrofac our well engineering teams have years of global experience in the design and execution of decommissioning programmes tailored to the specific structure and condition of each well. All wells are safely plugged and abandoned in accordance with regulatory standards, supported by a range of specialist services from supply chain partners. 

Secondly, facilities and pipeline isolation and cleaning. Here, all hydrocarbon systems are safely depressurised and cleaned. Pipelines and topside systems are flushed, purged, and physically isolated. Pressure vessels may require manual cleaning, and all waste is handled according to strict environmental protocols. Optimising this stage of the process is a key focus for Petrofac, with efficient planning and execution driving potential opportunities for both schedule and cost saving. 

The final stage prior to lighthouse mode, once cleaned and de-energised, is the topsides preparation phase. This involves readying the structure for its interim, near-dormant state and eventual removal. Key activities could include structural modifications, installation of lift points, and, depending on the size and type of the facility, some modules may also be separated, ready for future dismantling. Dropped object surveys and remedial actions are also carried out to ensure safety.  

Typically, the asset is disconnected from its main power systems and instead powered by independent sources, such as solar panels. It is then equipped with navigational aids (NAVAIDs), making it visible to vessels and aircraft operating in the area.  

FINAL FLIGHT

During these latter stages, personnel begin to leave the platform as the systems are shut down and operations wind down, culminating with a ‘final flight’, where the last of the operational crew leave the asset.

Alec Townley, Operations Manager of a platform about to enter lighthouse mode, reflects on his and his team’s experience of the process: “Offshore, you meet all kinds  -  first timers and veterans who’ve spent decades on the same platform. So, when decommissioning begins and the asset enters lighthouse mode, it’s emotional. There’s sadness in leaving what feels like a second home but also pride in all we’ve achieved. You can feel the history and hope the legacy lives on after the last flight home.”

MANAGING THE PAUSE 

Once these preparations are complete, the asset is officially placed into lighthouse mode.

During this stage, another key factor is meticulous documentation. This includes thorough preparation, ongoing observations, and detailed reporting of all activities and conditions. Through our Global Management System (GMS) and BuildME software, we can ensure operational integrity is maintained throughout the phase and carried forward into subsequent operations. Also, returning to an asset after any unmanned period comes with risk, so documentation enables the returning teams to understand the exact condition and status of the asset. This is crucial, not only for the safety of personnel on board and surrounding environment, but also for efficient execution of the next phases - reducing uncertainty and mitigating risk, resulting in more predictable and inherently lower-cost execution.

“Whether as duty holder, outsourced operator, well operator, or decommissioning partner, Petrofac brings deep experience and digital capability to help clients manage this phase with confidence,” says Ross Sutherland. “Our integrated systems streamline planning, enable real-time control, and maintain compliance. This turns the stillness of lighthouse mode into a strategically managed stage of the decommissioning journey.”

BRIDGING THE GAP

When an asset is in lighthouse mode it is no longer operational but not yet gone. This phase of the decommissioning process requires technical discipline, vigilant monitoring, effective documentation, and a strong understanding of the asset’s condition and history.

As the asset stands, identified by the lights of its NAVAIDs and awaiting the next stage of decommissioning, it serves as a beacon of all the hard work undertaken to reach this point – meticulous planning, careful execution, and a commitment to ensuring that, despite being inactive, the asset remains safe, compliant, and fully prepared for its final removal.

[1] Research & Markets, Offshore Decommissioning Market Report, 2025: Click here