Equinor has successfully delineated the 'Heisenberg' oil and gas discovery in wells 35/10-11 S and A in the North Sea, and has also proven oil in the Hummer prospect.
Preliminary calculations indicate that the size of the discovery is between 3.8 and 8.9 million standard cubic metres (Sm3) of oil equivalent (o.e.). This corresponds to 24-56 million barrels of o.e.
Resource estimates for Heisenberg prior to drilling were between 4.1 and 9.0 million Sm3 of o.e.
Preliminary calculations place the size of Hummer between 0.1 and 0.6 million Sm3 of o.e.
These are the first and second wells drilled in production licence 827 SB. This is additional acreage for production licence 827 S, where the original discovery was made. The drilling was carried out using the Deepsea Stavanger rig about 140 kms northwest of Bergen.
The production licence was awarded in the Awards in Pre-defined Areas (APA) in 2015, while the additional acreage, 827 SB, was awarded in APA 2022. Since then, a few companies have sold out and the current licensees are Equinor (51 per cent) and DNO Norge (49 per cent).
Geological information
The primary exploration target for well 35/10-11 S was to delineate the Heisenberg discovery made in 35/10-9 in the lower Hordaland Group in the Eocene. The secondary exploration target was the Hummer prospect in the Balder Formation in the upper Palaeocene to lower Eocene. Since 35/10-11 S encountered the primary target in the water zone, the 35/10-11 A sidetrack was drilled with the primary target of encountering Heisenberg upflank in the oil zone.
Well 35/10-11 S encountered a sandstone reservoir totalling about 10 metres with good reservoir quality in the Hordaland Group. The reservoir was aquiferous with traces of hydrocarbons.
In the secondary exploration target in the Balder Formation, the well encountered a 3-metre oil column in sandstone totalling 23 metres with poor to moderate reservoir quality.
Well 35/10-11 A encountered a sandstone reservoir totalling about 12 metres with moderate to good reservoir quality. This reservoir has a 12-metre oil and gas column in the Hordaland Group.
The gas/oil contact was encountered 1571 metres below sea level, and the oil/water contact was proven 1576 metres below sea level.
The well was not formation-tested, but extensive data acquisition and sampling were carried out.
Well 35/10-11 S was drilled to a measured depth of 1853 metres below sea level, and was terminated in the Rogaland Group in the Palaeocene.
Well 35/10-11 A was drilled to a measured depth of 1690 metres below sea level, and was terminated in the Hordaland Group in the Eocene.
Water depth at the site is 364 metres. The well has been permanently plugged and abandoned.
Source: Source: Norwegian Offshore Directorate
