Shell & ExxonMobil Boost UK Energy Supply
The design of the Cutter field Trident Monotower installation is based on the construction of offshore wind turbines and therefore rests on a single leg. The lower construction and maintenance costs - the fabrication cost alone is around 40% of that of traditional platforms - of the unmanned Monotower platform, compared to conventional designs, enables the access and recovery of small pockets of resources that previously would have been deemed uneconomical.
Using renewable energy sources that have zero CO2 emissions to power the platform further reduces the environmental footprint. The design of Cutter is virtually identical to that of the NAM (Nederlandse Aardolie Maatschappij, a 50/50 subsidiary of Shell Nederland B.V. and ExxonMobil) K17 platform in the Dutch sector of the North Sea. Using a common approach to design and installation for both platforms resulted in substantial cost savings for these cross-border fields.
Tom Botts, Executive Vice President, Shell Exploration & Production in Europe, said: "This is a world first in innovative, environmentally-sustainable design. Production from the Cutter field will increase Shell's contribution to UK security of energy supplies and highlights our continued commitment to development of North Sea opportunities. This is another step forward for Shell in developing marginal gas fields through world-class project management."
Malcolm Wicks, UK Energy Minister, said: "Every new development in the UKCS is important - but this development is a real example of innovative thinking, transferring the latest generation of renewable technology into the existing oil and gas industry to secure more energy for the UK without increasing carbon emissions."
Robert Olsen, Chairman and Production Director, ExxonMobil International Limited said: "We are pleased with the start-up of Cutter. It is an example of the use of an innovative approach to expand UK gas supplies. This project is further demonstration of our continuing commitment to the development of oil and gas resources in the North Sea."
Cutter is based in the southern sector of the North Sea, some 75 miles (120 km) from the Norfolk coast. It exports to the Bacton Gas Plant over the Shell-operated Carrack and Clipper platforms, a total distance of around 175 km in length to the UK Norfolk coast.
Plateau gas production is estimated to be some 3 million standard cubic meters of gas and associated liquids a day into the UK. The field is expected to be producing for at least 15 years. K17 plateau gas production is estimated to be some 2 million standard cubic meters of gas a day. Field life is expected to be some 20 years.
Equity Holding in the project is Shell with 51.35 and ExxonMobil with 48.7%.
The unmanned Monotower is not equipped with helidecks. Scheduled maintenance will be carried out once every two years with a jack-up rig while interim inspection visits will be made by boat, as is currently carried out on the Skiff, Brigantine and K7FB platforms.
Safety valves on the platform will be able to shut down production of the wells in case of emergency and the wells themselves are also equipped with subsurface emergency shutdown valves. The platforms carry equipment to inject corrosion and hydrate inhibitors into the wet gas pipeline as well as wind turbines and solar collectors for power, and the mandatory navigation lights.
The Monotower is also relatively light in comparison to traditional platform design (around 150 tons topsides and 250 tons substructure) so can be installed with a drilling rig rather than a large crane barge.
It has three main components. The foundation consists of a hollow pile 4.2 meters in diameter pushed into the seabed. The actual tower is placed on this pile, which projects from the seabed. To minimize the effects of hydrological forces as much as possible the diameter of the tower at sea level is a mere 2.5 meters. The actual platform is situated at a height of around 16 meters.
The Monotower incorporates renewable energy generation equipment to overcome the significant cost of providing a subsea cable to power the platforms, thus reducing environmental impact.