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Breathing new life into brownfield projects, Part 1

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Oilfield Technology,

Richard Wylie, Technip, sheds light on one of the North Sea’s most important brownfield redevelopment projects and outlines Technip’s contribution to the project.

Since the 1970s oil and gas production in the UKCS has been one of the most important sources of energy for Europe and the wider region.  At its height in the late 1990s, fields in the region were producing an estimated six million bpd of hydrocarbons. Production has inevitably slowed since the time of ‘peak oil’ and many of the North Sea’s historical operators and supply chain companies have started to explore other regions in the world with some in the process of decommissioning assets in the North Sea. 

Recent technological advances and investment have seen activity in the region surge once more. The development of new techniques and technologies mean that reservoirs that were previously considered to be inaccessible and uneconomical are now viable. Over the course of 2012 the region saw record levels of investment. Oil and Gas UK reported that companies looking to capitalise on these new developments spent US$ 14 billion on further exploration and development.

One such example of this is the Schiehallion field, which is located 175 miles off the West Coast of Shetland. Discovered by operator BP in the early 1990s, the company installed an FPSO in 1998 that currently processes the output from the four subsea centres at the site.

Extended lifespan

Originally engineered to support a field lifespan of 20 years, the current infrastructure has produced an estimated 300 million bbls over the 15 years since its installation.

However, since ‘first oil’ in 1998 the understanding of the Schiehallion and other fields has evolved significantly. Recent appraisal wells, drilled through the existing reservoir, indicated that there might be more than double the amount of recoverable reserves than previously thought. This major re-development will enable the potential recovery of an additional 450 million bbls of resource and extend production through to 2035.

In order to maximise this new potential at the site, up to 25 new wells will be drilled at Schiehallion, bringing the total to 52 wells. Achieving these targets will require an estimated US$ 5 billion of investment.

This investment will see the current subsea infrastructure undergo a full redevelopment as well as the replacement of the current FPSO with a purpose built asset equipped to deal with both the forecast production and the particularly harsh environment of the North Atlantic.

In all, 25 new subsea wells will join the existing infrastructure along with 17 km of new rigid pipeline, which is needed to connect each drill site and the new FPSO. The changes will also see new manifolds, flowline termination assemblies, umbilical termination assemblies and flowlines and umbilicals installed at each drill site in what will become one of the largest subsea systems in the world. 

This redevelopment is expected to greatly increase daily output from each drill site, and the field as a whole, with the redeveloped Schiehallion field, expected to produce 130 000 bbls of oil and 22 million ft3 of gas compression per day.

Given the scale of the project and the many changes that are required in order to maximise the field potential, the success will rely on the seamless integration of many smaller projects carried out by a range of subsea and oil service companies.

Integrated project

Technip in the UK will play a major role in the redevelopment of the Schiehallion site with a scope of work that will require almost all facets of the organisation to operate together. Technip’s Quad 204 team has been tasked with disconnecting the existing FPSO, installing the new floating unit when it arrives on site and mooring it securely in the existing location. The company’s remit also encompasses recovering the old moorings from the site.

In addition the company has been commissioned to completely replace the riser and mooring system that is currently in place. The project will necessitate the recovery of all flexible and umbilical risers. This will be followed by replacing the system with the installation of 21 bespoke flexible risers that will eventually be connected to the new FPSO as well as numerous new jumpers being installed on the seabed. The project scope also includes the installation of 15 additional rigid pipelines along with umbilicals and subsea structures.

In addition to the technical challenges that make this project unique from a Technip’s perspective, the environmental conditions mean that the riser and mooring system must be able to cope with 30 m waves and up to 80 m of lateral movement of the FPSO with no adverse effects. 

Whilst the company regularly carries out projects providing vessel support, engineering expertise, pipe lay and manufacturing, ROVs and personnel, we are now being asked by clients to provide a service that encompasses all of our services. 

A brownfield site, Quad 204 is different mainly because of the scale of the project. The scope of work does not encompass anything that Technip has not undertaken before; rather it brings together the company’s vertically integrated subsea business and capabilities. It draws, and will continue to draw, on our vast subsea experience for the delivery of the entire project scope.

Operationally this project has required the company to adapt its regular team structure significantly to cope with the demands Quad 204 has presented us with.  Operationally our teams are typically quite small, however the many components of Quad 204 has led to the adoption of a matrix structure in order to co-ordinate all aspects of Technip’s scope of work. Consequently it currently has more than 100 people working directly on the project, an important number for projects in subsea organisations.

Part 2 of this article can be reached here.

Adapted by David Bizley

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