It has been announced that a minor oil discovery has been found near the Vega Sør field in the north-eastern North Sea. The wells have been drilled approx. 4 km west of the Vega Sør field.
The primary exploration target for well 35/11-18 was to prove petroleum in Middle Jurassic reservoir rocks (the Brent group). The secondary exploration target was to prove petroleum in Upper Jurassic reservoir rocks (sandstones in the Heather formation).
In the primary exploration target, the well encountered the Brent group with a thickness of 275 m and moderate to good reservoir quality. The well proved light oil in the Tarbert and Oseberg formation, with columns of 11 m and 3 m, respectively.
In the secondary exploration target, the well encountered an 8 m hydrocarbon column with good to poor reservoir quality.
The objective of appraisal well 35/11-18 A was to investigate the extent of the reservoir and the hydrocarbon columns, and the well was drilled about 450 m south of the discovery well. The well proved oil and gas in two Upper Jurassic (the Heather formation) sandstones with net thicknesses of 33 and 24 m, respectively, with poor to good reservoir quality. The well encountered oil throughout the Brent group, which is 270 m, with moderate to good reservoir quality. The well also encountered a 46 m column containing light oil in the Lower Jurassic (the Cook formation). Preliminary estimates place the size of the discovery between 1 and 3 million Sm3 of recoverable oil.
Extensive data and sampling have been collected, including two formation tests in the Cook and Oseberg formation in 35/11-18 A. The tests show good flow properties with stable flow pressure and low pressure fall-off, with good permeability.
The wells are the second and third exploration wells in production licence 248.
Well 35/11-18 was drilled to a measured depth of 3759 m below the sea surface (3709 m vertical depth) and was terminated in Early Jurassic rocks (the Cook formation). The appraisal well was drilled to a measured depth of 4020 m below the sea surface (3874 m vertical depth), and was terminated in Early Jurassic rocks (the Statfjord group).
Water depth at the site is 366 m. The wells have been permanently plugged and abandoned. The partners in PL 248 will now evaluate the results.
Wells 35/11-18 & 18 A were drilled by the Borgland Dolphin drilling facility, which will now drill appraisal well 25/10-14 in the North Sea in production licence 571, where Suncor Energy Norge AS is the operator.
Edited from press release by Angharad Lock
Read the article online at: https://www.oilfieldtechnology.com/drilling-and-production/10122015/minor-oil-discovery-near-the-vega-field-1921/