KNOWLEDGE HUB
Disembarkation Procedure Overview
The definitive transition of an offshore asset from a manned, hydrocarbon-free installation to an unmanned state, commonly known as “lighthouse mode.”
Disembarkation represents the definitive transition of an offshore asset from a manned, hydrocarbon-free installation to an unmanned state, frequently referred to as “lighthouse mode.” This intensive process commonly spans 14 to 30 days and serves as the final bridge between engineering down and the eventual arrival of a heavy-lift removal contractor. The objective is to leave the platform in a safe, compliant, and optimised condition while systematically removing personnel and life-support systems.
Regulatory and Documentation Framework
A successful disembarkation is legally predicated on the approval and update of critical regulatory documents. The asset’s Safety Case must be formally revised and accepted by the regulator to reflect its status as an unattended installation. Without this acceptance, personnel cannot legally depart the platform. Other essential documentation includes an updated Oil Pollution Emergency Plan (OPEP), reflecting the absence of bulk hydrocarbons, and a “Consent to Locate” for the autonomous navigational aids required to warn sea traffic once the crew has left.
Technical and Physical Rundown
The physical preparation of the asset involves a disciplined, phased rundown of all utility and safety systems.
Accommodation and Catering
To reduce maintenance and stewarding burdens, living quarters are closed in blocks. In the final days, catering services are significantly reduced, often shifting to microwavable meals and disposable service to allow for the cleaning and preservation of the galley and the removal of remaining food stocks.
Engineering
Autonomous navigational aids are commissioned and tested, often featuring satellite links for remote voltage monitoring. Bird deterrent systems, such as bio-acoustics or squawkers, are installed during this window to prevent nesting during the unmanned period, which could otherwise delay future removal activities.
Safety and Life Support
Lifeboats are decommissioned in stages as the personnel count decreases, and muster points are adjusted to remain close to the final evacuation routes. Potable water makers are decommissioned, and systems are drained. Firewater pumps are typically the very last systems taken out of service, often on the day of departure.
Logistics and Backloading Strategy
The final days require a meticulous backloading strategy. This includes the recovery of rental equipment and vendor-owned assets to avoid unnecessary buy-out costs or commercial variations. Waste management is strictly monitored during this time to ensure that decommissioning waste is segregated from operational waste, preventing environmental non-conformance penalties.
Personnel and Competency Management
Selecting the team for the “final flight” is a strategic decision. This crew must be multi-skilled, possessing the specific competencies required. Because this phase involves turning off essential lifelines, such as power generation and drinking water, the crew operates under a prescriptive, “military-style” procedure where every role is defined and every action is sequenced to manage the increasing operational risks.
Stored Energy and IT
All remaining energy sources are managed, engineered down or are recorded in a Stored Energy Register. IT servers and sensitive data is either removed or physically destroyed to protect sensitive data.
Contingency Planning and Final Departure
Weather and helicopter availability remain significant risks to a disembarkation schedule. Logistics planning includes “if-then” scenarios for weather delays or technical failures in autonomous systems.
On the final day, a prescriptive departure procedure is followed to verify that the platform is safe and isolated, including verification of the energy register and ensuring that all access and egress routes for future removal crews are clear and documented.
Following the final flight, an onshore debrief can be conducted to capture lessons learned and acknowledge the significant operational milestone of the project’s completion.
Learn More on Lean Decom
In this class, you will receive a comprehensive overview of the disembarkation procedure, created using the learnings from performing five platform disembarkations at TAQA assets in the North Sea. Learn more on the decommissioning training course.