Design once, build many

August 1, 2017

Rob Gill and Steve Henzell explain how WorleyParsons intends to make wellhead facilities production cheaper and faster with a design one, build many ethos.

Images from WorleyParsons.

The pressure to reduce the cost of new developments has never been greater for North Sea operators. The combination of low oil prices, decreased North Sea development opportunities and increased competition from the US shale industry means that our industry’s being forced to adapt to new ideas.

One development concept that’s starting to gain traction is the use of low-cost wellhead platforms for the development of small satellite fields. These are typically newly discovered fields close to an established host platform, which can provide control and power and also carry out fluid processing.

While wellhead platforms have long been a favorite in the shallow waters of the southern North Sea, up until now, the preferred option for the development of satellite fields in deeper water has been to use a subsea manifold with a tieback to the host facility. Subsea manifolds are tried, tested and trusted, but, WorleyParsons has carried out a number of studies showing that they don’t necessarily provide the best value solution for a multiple well development. The difficulties and additional costs associated with maintenance and future well intervention operations can all contribute to increased costs over the lifetime of a project.

With 30+ years’ experience in the design of unmanned wellhead platforms, WorleyParsons has accumulated a reference list of more than 500 installations, which are currently operating throughout the world. The WorleyParsons team has combined this experience with ideas borrowed from the shale industry – where standardization and modularization of equipment is the key to low-cost field development – and they have come up with a new concept in wellhead platforms suitable for installation in deeper water and able to withstand North Sea conditions.

The new design uses piled foundations, can be deployed in water depths of up to 120m, and provides space for a maximum of 12 well slots. No accommodation has been provided for personnel who will gain access for four-monthly maintenance visits by vessels equipped with a “walk-to-work” gangway. The platform design includes a 5-tonne crane and sufficient deck space to allow full access for future well intervention. WorleyParsons has also designed the new platform for construction within their covered yard near Stavanger, Norway, and with one flat side to permit installation by either barge launch or jackup platform to widen the choice of installation contractor.

Minimal scalable facilities.

The platform is designed with a “design once, build many” approach to capture economies of scale and efficiencies more closely associated with a production line than a North Sea construction yard. The design borrows from the philosophies that WorleyParsons has previously followed in both the Persian Gulf and in the Gulf of Thailand, and uses a minimum number of different profiles to reduce procurement and stockholding costs.

Topsides and jacket weights are comparable to more traditional North Sea designs at around 650-tonne and 3500-tonne, respectively, for a 100m water depth platform. With almost all of the topsides and much of the jacket being identical for any platform regardless of water depth. However, there is scope for significant savings in project schedule by both reducing set up times and by allowing construction to start in parallel with detailed design. The design is so standardized that water depth, seabed conditions and well slot arrangement are the only pieces of information required to completely define an individual platform so further reducing project schedule and minimizing construction risk.

WorleyParsons sees an immediate market for at least 20 low cost modularized platforms in the Norwegian sector of the North Sea alone, and is currently talking to a number of operators who have been carrying out studies to assess their viability.  They also see applications in UK waters where the upcoming 30th licensing round will be targeting small pool discoveries which will require especially low-cost development schemes.

Rob Gill is a process engineer by background and has 30 years of technical, management, M&A and business development experience in the oil, gas, petrochemicals and manufacturing industries. Rob holds a BSc. in Chemical Engineering from Loughborough University and an MBA from INSEAD.

Steve Henzell is a process engineer by background and has over 30 years’ experience in oil and gas design and operations. He is an authority in the design of wellhead platforms and provides leadership in the areas of concept and front-end engineering design within the WorleyParsons Group. Henzell holds a BE in Chemical Engineering from the University of Queensland and is a Chartered Engineer in both Australia and the UK.

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