Succesful Appraisal Delivers New Gas at Johnston Field
Dana Petroleum reports that the 43/27a-4 well, being drilled to appraise the south-eastern area of the Johnston gas field in the UK Southern North Sea, has been successful. The initial vertical pilot hole found gas bearing sandstones in both the Rotliegend and Carboniferous horizons. The well was then sidetracked to drill a 2,850 feet horizontal section through the most productive Rotliegend reservoir section to provide an optimum offtake point for additional gas production.
The horizontal well has now been completed and will henceforth be known as the J4 producer. Well J4 has been production flow tested back to the Noble Julie Robertson drilling rig at rates of approximately 55 million cubic feet of gas per day (mmcfpd).
Following completion of the flow testing operations, the J4 well will be connected via an 8 inch diameter pipeline, some 6.9 kilometres along the seabed into the existing Johnston field infrastructure. The start-up of commercial gas production from J4 is expected during October and should significantly boost output from the Johnston field.
In the Central North Sea, drilling has also been completed on exploration well 23/11-4 having reached a total depth of 11,720 feet. The deeper Jurassic sandstone target was found to be present as prognosed and of good reservoir quality, but water bearing. However, the shallower Forties sandstones were found to be hydrocarbon bearing and, whilst the recoverable volumes present at this location are estimated to be small and non-commercial, these results provide encouragement for the further appraisal of the 23/11 block, which also contains an extension of the Barbara gas field.
Dana plans to drill two further important exploration wells before year-end. The first is scheduled in October to test the Clachnaben oil prospect in the Northern North Sea, where Dana holds a 79% stake. Clachnaben lies in Block 211/22a, adjacent to the Cormorant/Brent export infrastructure through which Dana's existing Hudson and Otter oil fields currently produce. This Brent sandstone prospect has the potential to contain around 60 million barrels of oil in place on a most likely basis. If drilling is successful, a fast-track subsea tie-back development would be pursued jointly with the adjacent 211/22a-1 discovery, drilled in 1977, which flowed 31 degree API oil.
Secondly, the Faucon well, in Block 1 offshore Mauritania, has been prepared for drilling in November and is targeting a structure with the potential to contain over one billion barrels of oil in place. Dana holds a 60% working interest in the Block 1 Production Sharing Contract (PSC).