Statoil’s Mariner field development project, located in the North Sea, is the largest new offshore development in the UK in more than a decade.
The field was discovered in 1981 and Statoil took over as operator in 2007. Thanks to drilling and process technology breakthroughs, it is only now that this heavy oil field has become economically feasible to develop.
The Mariner steel jacket is the largest ever built for a Statoil project. Weighing 22,400 tonnes, it is 135.5 metres high (taller than Big Ben and the Statue of Liberty) and has a footprint of 102 by 73 metres. The barge-launched jacket will support a large production, drilling and quarters (PDQ) topside facility which weighs 52,000 tonnes, and it will have 60 conductors. The Mariner field will contribute more than 250 mmbbls reserves with an average plateau production of around 55,000 barrels per day. The oil will be exported to a nearby floating storage unit and then to market by shuttle tanker. Production is expected to commence in 2017.
Our London offshore engineering office has a strong track record of integrating our project teams, systems and processes with those of our partners, to successfully deliver a number of offshore substructure EPC projects. This allows SNC-Lavalin to work effectively to deliver to demanding schedules, safely, on time and on budget.
We were first awarded the front-end engineering for the project in 2011, demonstrating our depth of expertise in a globally competitive market. Our successful delivery of the contract—in what is widely viewed as the most regulated offshore region in the world—led to the consequent award of the detailed design contract in December, 2012. The engineering work was awarded by Dragados Offshore S A as a subcontract.
Preventing injuries through design
Design safety was of particular importance in the jacket’s fabrication. We consistently delivered designs on time, enabling the fabricator to fabricate and install the jacket components on the ground. This meant that the fabricated parts could then be lifted together into their position which reduced the amount of work required to be carried out at height, mitigating health and safety risks.
As part of the risk mitigation, our engineers conducted simulated blast analysis and non-linear analysis such as boat impact, to improve the behaviour of the structure by assessing the effect of any resulting damage and ensuring progressive collapse does not occur.
We also ensured long-term integrity of the structure by detailed fatigue and fracture mechanics assessments and corrosion protection to ensure integrity for the 40-year life of the platform. This service life of the Mariner Jacket is roughly 15 years longer than other North Sea structures and imposes stringent requirements for fatigue performance of welds. As a result, we also performed very detailed and complex analyses for deterministic and spectral fatigue on the jacket structure.