Nexen spreads its wings

Field development prospects on the UK Continental Shelf are gathering momentum again, with Nexen (Golden Eagle, Blackbird), Chrysaor (Solan) and BG (Blake increased production) firming up North Sea project and environmental impact details in recent weeks, and Total adding another West of Shetland gas and condensate find to its Laggan-Tormore area inventory. Meg Chesshyre reports.

Nexen Petroleum is looking to develop the Golden Eagle Area Development (GEAD) and the Blackbird field in the central North Sea. GEAD is in blocks 20/1N, 20/1 (Pink area) and 14/26a. It will be developed with a platform complex. Blackbird is primarily located in block 20/2a with the field extending to blocks 20/3a and 20/3f. It will be a subsea tieback to the Ettrick FPSO, the Aoka Mizu, also in block 20/2a.

GEAD will comprise two subsea drilling/ production centres and a heavy duty jackup drilling rig over a newly installed wellhead platform that will be linked by a 70m bridge to a fixed production/utilities/ quarters platform. Hydrocarbons will be processed on the platform complex, with gas separated and exported to St Fergus via the Scottish Area Gas Evacuation (SAGE) system through an existing connection point for the neighbouring Ettrick field, and oil exported either to the Forties Pipeline System (FPS) or to the Flotta terminal.

The development will entail up to 17 production wells, targeting the oil reserves in the Golden Eagle (Burns and Punt) and Pink (Burns and Punt) fields. Seven water injection wells will be required and each production well will require gas lift. The majority of the wells will be drilled by the jackup rig over the wellhead platform in the centre of the development area, in a water depth of about 100m. The remaining wells will be drilled by a semisubmersible at two satellite drill locations, one to the north and one to the south of the development area.

First oil production from GEAD is expected in 4Q 2014, and the proposed development has an anticipated lifespan of 25 years. Oil production is expected to peak 2016-18 with a maximum production rate of 70,000b/d.

Nexen holds 100% of block 14/26a and 34% and 46% respectively in block 20/1N and block 20/1 (Pink area). Its partners in the GEAD licences are Maersk, Petro- Canada and Edinburgh Oil & Gas.

Meanwhile, Nexen is proposing to develop the Blackbird field as a subsea tieback to the Ettrick FPSO. The Blackbird development will initially consist of a single production well and one water injection well (drilled by a semisubmersible about 7km south of the Ettrick field). Development of future wells will be based on a developing understanding of the reservoir construction. The flowlines and umbilical will be installed by the latest addition to the Subsea 7 pipelay and construction vessel fleet, Seven Pacific, which recently mobilised for its maiden offshore assignment in Angola's block 18. First oil production is expected in January 2012.

Nexen Petroleum UK has an interest of just over 64% in Blackbird and its co-venturers are Nexen Ettrick UK, Dana Petroleum and Atlantic Petroleum.

Solan switch
Chrysaor has made an amended application to the UK Department of Energy (DECC) for consent to produce oil and gas from the proposed Solan field development in the Faroe Shetland Channel block 205/26a using a different development approach from that originally envisaged. For this not normally manned installation, in 132m of water 60 miles north-west of the Orkney coast, the company now favours a standard steel jacket structure over an articulated tower design.

Chrysaor said it initially assumed Solan's water depth and wave environment would render a fixed structure prohibitively expensive compared with the articulated tower option, but subsequent market soundings and discussions with fabricators had shown that a fixed structure's capex to be comparable at the expected design weights. Other factors cited by the company as influencing its switch to a standard steel jacket structure included reduced operating risk to personnel, more straightforward and conventional construction and insignificant additional environmental impact.

Premier Oil entered into an agreement with Chrysaor to become a partner in the Solan field in July 2010. On final sanction of a field development plan for Solan by the Chrysaor board, Premier will be granted an option to acquire a 40% non-operating interest in the field. If Premier exercises the option it will pay a bonus on FDP approval by DECC, a carry of 20% of the development project costs and a contingent bonus on completion of the project.

The Solan project schedule has been revised, with first oil now targeted in 3Q or 4Q 2012.

Blake boost
Operator BG has submitted an environmental statement covering increased production at the Blake field located in blocks 13/24a, 13/24b and 13/29b of the central North Sea in the outer Moray Firth. Blake is tied back to the Talismanoperated Bleo Holm FPSO in block 13/28a about 9.5km southwest of the Blake manifold.

BG proposes to increase production from Blake which has been estimated at a maximum increase from DECC-consented volumes of 1641m3 (10,332bbls) of oil per day with smaller volumes of associated gas being produced. Maximum gas production has been estimated at total of 343,757m3 per day. The average annual increase of oil for the first three years (2010-12) is estimated at 1498m3 (9422bbls) of oil per day.

The increase in production is estimated to take place between 2009 and end of field consent (2015), the field will then continue to produce until 2020. Peak production increase is anticipated to occur in 2011; however, peak oil and gas total production will occur in 2010 and steadily decrease throughout field life.

BG, which has a 44% stake in the Blake field, said the production increase would require no change to the subsea infrastructure or to the FPSO. The other Blake equity holders are Talisman Energy (Rigel Petroleum UK, Talisman North Sea and Talisman Energy UK) and Idemitsu Oil & Gas.

Shetland success
Elsewhere on the UKCS, a new West of Shetland gas and condensate discovery was confirmed in January by Total E&P;UK, close to its Laggan and Tormore fields currently under development (OE January 2010).

The Edradour exploration well lies in block 206/4, 75km northwest of Shetland in 300m of water. Drilled to a depth of more than 3500m, the well encountered gas and condensate in a Cretaceous reservoir with good petrophysical properties. Total said formation evaluation, including an extensive sampling programme, had been undertaken and that it would be studying potential development of these new resources through the Laggan-Tormore facilities once the Edradour appraisal phase is complete.

Commenting on the discovery, Patrice de Viviès, Total Exploration & Production's senior vice president, northern Europe, said: ‘While definitive testing is still to be completed, Edradour already is another meaningful discovery for us in the West of Shetland region. It should reinforce our third production hub on the UKCS around the Laggan and Tormore fields, after the success of our existing Alwyn and Elgin Franklin hubs.'

Total has a 75% operating interest in the Edradour licence, with Dong holding the remainder. Total (80%) is also partnered by the Danish company in the Laggan-Tormore development, which was sanctioned in March last year and is scheduled to produce first gas in 2014. OE

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