To date, 2009 has seen just seven wells spudded on the UK Continental Shelf, half the number recorded for the first two months of 2008.
However, 10 rigs, a drillship and a platform currently engaged in exploration and appraisal drilling may still be considered a relatively healthy number and compares favourably with 14 units at the end of February, 2008.
Currently, one well is active West of Shetland: Chevron’s Rosebank North 213/27-3, targeting Palaeocene sands.
In the Northern North Sea, CNR’s Murchison platform is being utilised to drill 211/19a-M75Z, deviating to appraise the Delta discovery on former Revus Norway block 33/9 – so arguably not a UKCS well.
In the Central North Sea, (CNS), Nexen’s 20/1-8 (Hobby) continues operations, having recorded a discovery, as do Talisman’s 22/17-4Z (Godwin) appraisal sidetrack; CNR’s (Deep Banff) appraisal 22/27a-4; BG’s 23/21-7X (Columbus) appraisal, in a third sidetrack, and Shell’s (Fram) appraisal 29/3c-8Z, which is a recently initiated geological sidetrack.
Immediately south of the CNS, on the Mid North Sea High, ExxonMobil has spudded well 37/25-1 on the Corbenic prospect, chasing potentially large reserves of gas, but in a high-risk Devonian play. In the Southern North Sea, four wells are active, including two new spuds: Century’s Permian appraisal 48/25c-6 on Vulcan Northwest and, following back-to-back with well 3, GDF’s (Cygnus area) 44/12a-4 Carboniferous appraisal.
Operations also continue in the gas basin on Venture’s (Carna) Carboniferous exploration sidetrack 43/21b-5Z and Venture’s Permian (Kew) appraisal sidetrack 49/4c-7Z.
Highlights from recent activity include Dana’s successful 210/24a-12 on the Jurassic South-east Rinnes prospect in the NNS, which encountered oil-bearing Brent sands and was confirmed with a downdip northerly sidetrack encountering more than 122m (400ft) of oil column.
In the CNS, Endeavour’s Lower Cretaceous Rochelle appraisal 15/27-11 encountered 23.5m (77ft) of net pay and flowed gas at 41million cu ft and 2,300 barrels of condensate per day.
Nexen’s 20/1-8 on the Hobby prospect encountered high-quality Jurassic reservoir in a significant column, and a multiple sidetrack programme is being undertaken to establish the extent of this find and relationship with the nearby Golden Eagle discovery.
A positive result is also expected on Talisman’s Godwin prospect, where an appraisal sidetrack, 22/17-4Z, was initiated following the initial 94-day exploration leg which ended in mid-February and was targeting a Jurassic prospect.
In the SNS, GDF-Suez’s Cygnus 44/12a-3 appraisal was successfully drilled, and tested the primary Permian reservoir in line with expectations and the secondary Carboniferous sands at a rate of 32million cu ft per day of gas.
Despite evidence of rig and vessel rates dropping, the current levels of drilling are unlikely to be sustained throughout the remainder of 2009 and will not match the 44 exploration and 33 appraisal wells spudded in 2008, to say nothing of the eight exploration sidetracks and 28 appraisal sidetracks also initiated last year.
What is clear, however, is that the UKCS sector continues to produce potentially commercial finds, and the process of rapidly moving from exploration through appraisal to development appears to be becoming more efficient.
Simon Robertshaw is with drilling analysts Hannon Westwood
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