Fabrication in focus

Specialist offshore fabricators continue to innovate in pursuit of an oil & gas market edge. Meg Chesshyre opens this month's yards round-up with a review of progress on the latest additions to Centrica Energy's North Sea infrastructure.

Centrica’s 2750t York platform has taken just over one year to complete from design through to build following contract award to the Heerema Fabrication Group’s (HFG) UK yard in February last year. Built in the HFG Hartlepool facility’s indoor fabrication halls in Hartlepool, the platform was due – weather permitting – to be installed last month by sister company Heerema Marine Contractors’ DCV Balder in 43m of water using dynamic positioning to minimise the environmental disturbance. Offshore hook-up is expected to be completed in August ready for first gas in early 2013.

The Centrica York jacket and topsides (left) nearing completion in Hartlepool; and (below) on sailout.

Saipem has an EPIC contract for the new 16in diameter and 3in diameter 34km pipelines to Easington. The line pipe has been delivered and work on the landfall has begun. The beach pull is due to start this month from a shallow water vessel, which will lay the pipe down about 13km offshore. The remainder of the pipelay will be carried out by the Castoro 7. The Noble Julie Robertson is carrying out development drilling, which will involve the tieback of an existing well on the east reservoir, and the drilling of two new wells into the larger southern reservoir.

The York development comprises a 1200t not normally manned three-tier topsides with emergency overnight accommodation for up to 15 personnel and a six-slot well bay, plus a 1550t jacket, with four skirt piles weighing 800t.

‘Great team work and commitment to high performance and safety.’ Wim Matthijssen, HFG

HFG York platform project manager Steven Turner says the platform is a fairly standard North Sea design but that the main challenge on the project had been the schedule, moving into fabrication three months after contract award with a relatively immature design and being able to manage those risks through the fabrication phase. ‘I think we got 99% okay. As always there’s a few things in the project we did not anticipate.’

Centrica offshore project manager, Ray Sheldon, agrees that it has been a really fast track project with a very successful working relationship between Centrica and Heerema. He explains that the platform has been designed as hub with spare risers and 2500m2 of free deck space. The export line has been sized at 16in in diameter, rather than the 12in required for York’s maximum flowrate of 12mmcf/d, to give ullage. There are two more subsea reservoirs which can be developed from the platform – West York and Vaduz, plus the possibility of third party tiebacks. The base case for York is an eight-year field life, but the platform and pipeline have been designed for 25 years, again so that it can act as a hub.

The York platform’s emergency accommodation room (far left); pipework installation and node fabrication for the York topsides.

York’s southern reservoir shares a common fault with Rough, 3km away, so monitoring equipment is being put in place to ensure that there is no cross-draining between the reservoirs. ‘Once we get down to a certain pressure level in the reservoir we will then monitor if there is any cross draining. If there is not then we can continue further down and bring the pressure further down, which means we can actually exploit more gas out of the reservoir,’ Sheldon adds.

This is the third project delivered by the partnership between Centrica Energy and Heerema, starting with the innovative 7100t F3-FA self-installing platform built under an EPIC contract by HFG’s Vlissingen yard and brought onstream 18 months ago in the Dutch North Sea (OE January 2011).

The second project, delivered last summer, was the Ensign field’s 1100t Sea Harvester design platform, built at Heerema Hartlepool and installed in southern North Sea blocks 48/14a and 48/15a by Seaway Heavy Lifting’s Stanislav Yudin last summer. Like F3-FA, Ensign was among a batch of offshore assets reassigned to Centrica following its 2008 acquisition of Venture Production. The field was originally discovered by Shell in 1986, but commercial viability proved elusive and a quarter of a century would elapse before it yielded its first in early May this year. New operator Centrica attributed this success to the use of hydraulic fracturing, building on its existing expertise in developing tight gas reservoirs.

Acknowledging the good progress made on the York project, HFG chief operating officer Wim Matthijssen attributed the successful delivery of this EPCI project to ‘great team work and commitment to high performance and safety’ by Centrica Energy, HFG and other partners. ‘It demonstrates the dedication and experience of everyone involved to get projects such as this completed on schedule and, most importantly, safely,’ he added.

The Hartlepool yard is also building an 800t Kinnoul process module for BP’s Andrew project. This is due for loadout in August.

Centrica is 100% owner of the York field (in blocks 47/3a, 47/3a, 47/3d and 47/3e), the new pipeline to shore and the Easington terminal, making it easy for third party access. Capital expenditure for York and Ensign together is put at £450 million – with York costing twice as much as Ensign, which would indicate a capex figure for York alone of around £300 million.

Strong performance

With eight new developments coming onstream and seven successful exploration wells, Centrica Energy has had a strong production performance in the North Sea in 2010 and 2011, observes Greg McKenna, the company’s incoming southern North Sea regional director. The F3-FA Dutch sector gas field is performing above expectations, including producing a substantial amount of high value condensate. In the Morecambe Bay area, Centrica is looking at debottlenecking and well enhancement, which could lead to another 20 years of production from the complex. The Rhyl field is being developed this year as a single well tieback to the Morecambe North field centre.

Centrica’s Greg McKenna (right) with HFG’s Wim Matthijssen at the Hartlepool yard.

Centrica is currently operating three drilling rigs on the UKCS: Noble Julie Robertson on York development drilling, Noble ton van Langeveld in the central North Sea and Noble Byron Welliver in the Irish Sea. The company is drilling on average 10-12 wells a year and its annual exploration budget is running at about £100 million. It also has an extensive seismic programme, including re-evaluating existing areas such as Markham or the east Irish Sea.

Centrica has made significant acquisitions in Norway, including Shell and ConocoPhillips’ interests in Statfjord, and a stake in Valemon, the largest high pressure, high temperature gas development in Norway. It has three operated exploration discoveries. In December last year, early appraisal results from the Butch prospect (operated by Centrica Energy with a 40% share) indicated a significant presence of light oil in the reservoir with additional volumes already being targeted on the greater Butch area. A project team is now being set up to look at field development potential.

Centrica entered Trinidad & Tobago in 2010 through the acquisition of Suncor. The biggest potential development there is block 22, which will be a subsea development with a pipeline back to the beach with either an LNG or CNG plant probably on Tobago.

Centrica has built up a portfolio of about 1 billion boe of reserves (19% oil and 81% gas), of which 53% are in the UK and Netherlands, 28% in Norway and 19% in Trinidad & Tobago. The company has an ambition to grow production by 50% in the next three to five years, taking it to 75 million boe/year. It is investing £1.5 billion in nine current projects with a production potential of around 140 million boe.

In addition to Ensign, 2012 will see Seven Seas in the UK, Rhyl in the east Irish Sea and Atla in Norway all coming onstream. They will be followed by Kew, Annabel East and York on the UKCS in 2013, and Valemon (Norway) and Cygnus (UK) in 2014. FID is expected shortly for the £1.2 billion-plus GDF Suez-operated Cygnus field development, probably the biggest gas development on the southern North Sea in the past ten years, which will require four platforms. OE