A single spud and sidetrack during December has raised the UKCS total to 66 well starts – 27 exploration spuds and five sidetracks, plus 20 appraisal “spuds” and 14 sidetracks – in 2010.
At the end of the year the number of mobile rigs active on E&A (exploration & appraisal) drilling was seven.
The number of production & development wells, excluding workovers and other interventions, for the year climbed to an end tally of 123 (including 57 sidetracks), with 16 active at year-end from seven platform-based derricks and nine mobile rigs.
The northern North Sea is currently devoid of any E&A drilling. Xcite suspended Bentley heavy oil appraisal 9/3b-6Z after approximately 65 days, releasing the semi-submersible Ocean Nomad. Xcite has suspended the well for potential use as a future producer.
EnQuest abandoned unsuccessful Don Southwest appraisal well 211/18a-28. However, the Transocean John Shaw semi-submersible stays in the area and is shortly to commence further drilling for this operator.
Chevron’s 217/15-1 well on the Lagavulin prospect, west of Shetland, remains active and is being drilled using the Stena Carron.
Total’s Edradour well 206/4-2 has been successful, and the rig Sedco 714 has been carrying out operations to suspend rather than abandon the borehole.
Four wells are active in the central North Sea: EnCore’s successful 28/9-2 exploration well on the Varadero prospect using the jack-up Galaxy II; Maersk’s Culzean HP/HT (high pressure/high temperature) appraisal 22/25a-10Z with jack-up Ensco 101; BG’s Jackdaw appraisal 30/2a-8 with jack-up Rowan Gorilla VI, and Talisman’s Josephine appraisal re-entry, 30/13a-9 utilising the semi-submersible Ocean Princess.
Semi-submersible Transocean Prospect was released to port following Nexen’s short Bluebell exploration/Buzzard appraisal well 20/6a-7. The outcome has yet to be publicised.
Just a single well remains active in the southern North Sea. Centrica’s Pegasus prospect well, 43/13b-6, being drilled by the Noble Julie Robertson jack-up was sidetracked in early December.
At the end of September 2010, we predicted that there was potential for a further 10 exploration and appraisal wells to start before year-end. In the event, records indicate just six wells spudded in that period. Much of the shortfall can be attributed to the weather, which certainly played its part in protracting active rig operations and delaying new starts, particularly those planned for the 28/9 Catcher area.
Despite the lack of a Q4 flurry, a preliminary review of 2010 indicates a good year for discoveries. Oil was found by Valiant at Tybalt in the northern North Sea, by Wintershall at Blakeney, Maersk at Balloch, Nexen at Polecat, EnCore at Catcher and Varadero in the central North Sea and by Hurricane at Whirlwind to the west of Shetland. In the southern North Sea, gas was discovered at Platypus by Dana and at Olympus and Fulham by Centrica.
Progress was made with the appraisal of Nautical’s Kraken and Xcite’s Bentley heavy-oil finds, Sterling’s Cladhan and TAQA’s Tern North oil discoveries in the Northern North Sea. There was appraisal success for Nexen at Blackbird and West Rochelle, Ithaca at Stella in the CNS, ATP at Kilmar, Centrica at York East and GDF SUEZ at Cygnus in the southern North Sea. West of Shetland, Hurricane successfully appraised Lancaster.
With seven 2010 starts remaining active, we expect the success rate for the year, currently hovering around the 40% mark, to improve further as more results come to light.
Whilst 47 new well starts a year may challenge the potential to satisfactorily drill out the UK resource, the success rate indicates a continued ability to mitigate E&A risk better. Happily, 2010’s crop of successes adds to the already significant backlog of undeveloped discoveries on the UKCS, the exploitation of which poses the next great challenge for the North Sea industry.
Simon Robertshaw’s column is courtesy of North Sea drilling analysts Hannonn Westwood
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