Delineation of the 35/12-2 (Grosbeak) oil and gas discovery in the North Sea – 35/11-21 S and 35/11-21 A

29.10.2018
Wellesley Petroleum AS, operator of production licence 248 I, has concluded the drilling of appraisal wells 35/11-21 S and 35/11-21 A on the 35/12-2 (Grosbeak) oil and gas discovery.

The wells were drilled about 10 km northeast of the Fram field in the northern part of the North Sea, and 84 km southwest of Florø.

The discovery was proven in 2009 in Jurassic reservoir rocks, with gas in the Upper Jurassic (the Sognefjord formation) and oil in the Upper and Middle Jurassic (the Fensfjord formation and the Ness formation). Prior to the drilling of wells 35/11-21 S and 35/11-21 A, the operator’s resource estimate for the discovery was between 1.8 and 16 million Sm3 of recoverable oil and between 0.2 and 2.5 billion Sm3 of recoverable gas.

The objective of 35/11-21 S was to prove an oil-filled reservoir in the Ness formation and oil down in the underlying Etive formation. For 35/11-21 A, the objective was to encounter the oil/water contact, either in the Ness or the Etive formation, to prove an extension of the discovery in the Fensfjord formation, to collect data for development of the discovery, and to prove a western extension of the Ness formation.

Well 35/11-21 S encountered a total oil column of about 90 metres in the Ness and Etive formations, of which 45 metres of effective reservoir in sandstone with good to very good reservoir properties. The oil/water contact was not encountered.

Extensive data acquisition and sampling have been performed in well 35/11-21 S, including a formation test in the Ness formation. The flow rate was restricted to 996 Sm3 oil per flow day through a 48/64-inch nozzle opening, which shows very good production properties.

Well 35/11-21 A encountered a total oil column of about 50 metres in the Ness formation, of which 15 metres was effective reservoir in sandstone with good reservoir properties. The oil/water contact was not encountered. An oil column of about 8 metres was encountered in the Fensfjord formation, of which 2 metres was effective reservoir in sandstone with moderate to good reservoir properties. There was a one-metre gas column over the oil column, but no gas/oil contact was encountered. The western extension of the discovery in the Fensfjord formation was confirmed. In addition, a gas column totalling about 45 metres was encountered in the Sognefjord formation, of which 20 metres was effective reservoir in sandstone with very good reservoir properties. The gas/water contact was not encountered. Extensive data acquisition has been carried out in the 35/11-21 A well. The well was not formation-tested.

Preliminary estimates indicate that the size of the discovery in the Ness and Etive formations is between 7 and 17 million standard cubic metres of recoverable oil and between 1.1 and 2.7 billion standard cubic metres of recoverable gas. Preliminary estimates of the size of the discovery in the Sognefjord and the Fensfjord formations is between 1 and 2 million standard cubic metres of recoverable oil and between 6 and 9 billion standard cubic metres of recoverable gas. The licensees will assess the discovery together with other nearby discoveries/prospects with regard to a potential development/further follow-up.

These are the first and second exploration wells in production licence 248 I. Production licence 248 was awarded in 1999. Production licence 248 I was carved out in 2017.

Wells 35/11-21 S and 35/11-21 A were drilled to respective vertical depths of 2564 and 2614 metres, and respective measured depths of 2776 and 2907 metres below the sea surface. Both wells were terminated in the Cook formation in the Lower Jurassic. Water depth at the site is 360 metres. The wells have been permanently plugged and abandoned.

Wells 35/11-21 S and A were drilled by the Transocean Arctic, which will now drill wildcat well 30/6-30 in the northern North Sea in production licence 825, where Faroe Petroleum is the operator.

 

Contact in the NPD
Eldbjørg Vaage Melberg, tel. +47 51 87 61 00

 

35/11-21 S and 35/11-21 A