The decommissioning of the Jolliet tension-leg platform (TLP) and the connected Marquette platform in the US Gulf of Mexico in July of last year exemplifies a growing industry focus on removal strategies as major offshore assets reach the end of their operational lives. Originally installed in 1989 as a deepwater breakthrough, production from the platforms had dwindled significantly, leading owner MC Offshore Petroleum and its partners to initiate decommissioning amidst market uncertainty and regulatory pressures.

Accelerating Decommissioning Wave

Industry analysis indicates a significant acceleration of decommissioning activity in the US Gulf over the next decade, driven by the aging of pioneering deepwater infrastructure from the 1980s and 1990s. Global offshore decommissioning liabilities are estimated at about $300 billion, with nearly $40 billion located in the US Gulf. Through 2030, operators in the region are projected to spend more than $3.5 billion on decommissioning, signaling a major shift in operational priorities.

Market Dynamics and Challenges

The market is evolving as operators increasingly consider decommissioning. Some later-life assets were previously sold to smaller operators for life extension work, but these efforts have limits. In some cases, assets have "boomeranged" back to original owners after smaller operators went bankrupt, returning the decommissioning liability. While a few creative approaches to avoid full removal are being explored, decommissioning is becoming a central theme for deepwater assets. Key challenges include managing costs, potential contractor and heavy-lift vessel availability tightness, and rising bonding costs—funds regulators require operators to set aside for future decommissioning, which have become a significant hurdle for mid-sized companies.

Execution and Collaborative Models

The Jolliet-Marquette project involved a complex, collaborative execution model. MC Offshore managed over 40 subcontractors, utilizing five vessel companies and specialists for topsides cleaning and pipeline abandonment. This integrated approach, mirroring practices long used in the North Sea, is becoming more common in the US Gulf. A critical preparatory phase was the plugging and abandonment of 33 wells across both platforms.

Innovative Removal Techniques

The physical removal required innovative solutions, particularly for the TLP structure. Marquette's deck was split into two pieces, with the heaviest section weighing 2400 tonnes. A key deviation from conventional practice was the method for cutting the tendons mooring the platform. Instead of cutting and removing them one at a time while tugs held the structure, the team used a mechanical lifting clamp to cut all tendons simultaneously beneath the seafloor template. This approach, completed within a day and a half, significantly reduced operational risk and time compared to the traditional sequential method.