Wintershall Norge AS, operator of production licence 475, has concluded the drilling of appraisal wells 6407/1-7 and 6407/1-7 A.
The wells were drilled about eight kilometres northeast of the Tyrihans field and five kilometres northeast of the 6407/1-6 S gas condensate discovery in production licence 475. The reservoir in this discovery consists of thin sandstone layers from the Lange formation in the Lower Cretaceous. The discovery was made in January 2013. The resource estimate for the discovery was then between 3 and 20 million Sm3 of recoverable oil equivalents.
The objective of well 6407/1-7 was to delineate the 6407/1-6 gas/condensate discovery higher up in the structure. A new appraisal well, 6407/1-7 A, was therefore drilled downflank to investigate reservoir thickness and lithology.
Well 6407/1-7 proved gas/condensate in two sandstone intervals with a net vertical thickness of 12 metres and a gross reservoir thickness of 16 metres. Well 6407/1-7 A proved gas/condensate in two sandstone intervals with a vertical thickness of seven metres and a gross reservoir thickness of 13 metres.
The difference in pressure measurements between wells 6407/1-7, 6407/1-7 A and the discovery well 6407/1-6 S indicates that there is no communication between the appraisal wells and the 6407/1-6 S discovery. Well 6407/1-7 has therefore proven a separate discovery, and will be reclassified as a wildcat well.
Preliminary estimates of the size of the new gas/condensate discovery range from 1 to 4 million Sm3 of recoverable oil equivalents.
The resource estimate for the 6407/1-6 S gas/condensate discovery has now been downgraded to between 1 and 6 million Sm3 of recoverable oil equivalents. The licensees will consider the discoveries in conjunction with other nearby discoveries as regards future development.
This is the second and third exploration well in production licence 475. The production licence was awarded on 29 February 2008 (APA 2007).
Wells 6407/1-7 and 6407/1-7 A were drilled to vertical depths of 3345 and 3311 metres, respectively, below the sea surface, the latter with a measured depth of 3571 metres. Both wells were terminated in the Lange formation in the Early Cretaceous. Water depth at the site is 280 metres. The well has been permanently plugged and abandoned.
Wells 6407/1-7 and 6407/1-7 A were drilled by the Borgland Dolphin drilling facility, which will now proceed to production licence 550 in the northern part of the North Sea to drill wildcat well 31/2-21 S, where Tullow Oil Norge AS is the operator.
Press Release, April 10, 2014; Image: Dolphin Drilling