KNOWLEDGE HUB
Topside Preparation and Removal
One of the most visible and high-stakes phases of offshore decommissioning, coordinating industrial transition from production to dismantlement.
Classified as Phase 5 and Phase 6 within the OEUK Work Breakdown Structure, these stages typically account for 10 to 12 percent of total project expenditure.
The reason why this phase is particularly high stakes is due to the high costs of heavy lift vessels, potential delays, and the risk of re-embarking an asset after it has been separated. Therefore, the planning and execution of this phase are critical to optimising cost efficiency without compromising safety.
The EPRD Contract
This process is often packaged in an EPRD contract, which stands for Engineering, Preparation, Removal and Disposal.
The engineering phase focuses on structural analysis, lift studies, transport design and dismantling methodologies. Engineers must understand how the structure has aged, where residual hydrocarbons may remain, and how weight distribution has changed over time.
Topside Removal Strategies
The removal strategies are normally split into three different categories: single lift, reverse installation, and piece small.
Single Lift
The single lift approach uses ultra-heavy lift vessels such as Pioneering Spirit. These vessels can remove an entire topside in one lift; however, significant preparations are required. This includes structural strengthening, lifting bracket installation, and dropped object mitigation. The execution itself involves cutting the legs, separating the platform from the substructure, and lifting the topside to a disposal yard, often requiring transfer to a barge as an intermediary step.
Reverse Installation
For smaller platforms, or larger platforms where weight limits prevent a single lift, a reverse installation method is adopted. This involves removing modules individually, often in the opposite order to how they were originally installed, hence reverse installation. Modules are lifted onto vessels and transported to shore. While this method increases offshore duration, it can be a preferred option due to the preparation requirements associated with a single lift.
Piece Small
The piece small strategy involves dismantling the topside into smaller components using the platform cranes. However, it increases complexity and risk and is therefore not common practice.
Topside preparation and removal are far more than a lift event. They represent a coordinated industrial transition from production to dismantlement. Success depends on early engineering clarity, disciplined preparation, and a strategy aligned to asset size, risk profile and commercial realities.
Learn More on Lean Decom
To gain real-life insight into the realities, challenges, and common pitfalls of topside preparation and removal, you will acquire a detailed understanding of single lift and reverse installation from real projects on the Lean Decom training course. This comprehensive overview delivers field-proven efficiency drivers and strategic lessons learned from the Brae Bravo case study, additionally the course includes an EnQuest’s case study that features a single lift operation — learn more by accessing the Lean Decom training.