Wintershall in minor oil discovery in North Sea

Wintershall Norge is in the process of completing the drilling of four wells near the Vega field in the North Sea, offshore Norway. The company has made a minor oil discovery. 

The four wells are located in the production license 248 F where Wintershall is the operator.

The wells are wildcat well 35/11-20 S, the appraisal well 35/11-20 A and wildcat well 35/11-20 B. Due to technical issues, well 35/11-19 S had to be abandoned, and well 35/11-20 S was drilled about 50 meters southwest of 35/11-19 S.

The well 35/11-20 A was classified as a wildcat well, but will now be reclassified as an appraisal well.

The wells were drilled about five kilometers southeast of the Vega field in the North Sea and 100 kilometers southwest of Florø.

Results

According to the Norwegian Petroleum Directorate (NPD), the primary and secondary exploration targets for well 35/11-20 S were to prove petroleum in Late Jurassic reservoir rocks (intra Heather formation sandstone).

The well did not encounter reservoir rocks in the primary exploration target. The well encountered an 8-metre oil column in the secondary exploration target at the top of an intra Heather formation sandstone with poor reservoir quality and a total thickness of about 70 meters.

The objective of well 35/11-20 A was to delineate the oil discovery in intra Heather formation sandstone, and to prove petroleum in Middle Jurassic (Brent group) and Early Jurassic (Cook formation) reservoir rocks.

The well encountered a total oil column of 33 meters in intra Heather formation sandstone, of which 19 meters were of good reservoir quality. Due to technical issues, it was not possible to reach the Brent group and Cook formation.

Well 35/11-20 B was drilled to further delineate the oil discovery in intra Heather formation sandstone. The secondary target was to prove petroleum in Middle Jurassic (Brent group) and Early Jurassic (Cook formation) reservoir rocks.

The well encountered a total oil column of 46 meters in intra Heather formation sandstone, of which 29 meters were of moderate reservoir quality. A total oil column of 19 meters was encountered in the Tarbert formation in the Brent group, of which 10 meters were of moderate reservoir quality. The Cook formation was encountered with a total thickness of about 170 meters with predominantly poor reservoir quality and only traces of petroleum.

Preliminary estimates place the size of the discovery between 1.5 and 4.5 million standard cubic meters (Sm3) of recoverable oil equivalents. The licensees will evaluate the discovery along with other nearby discoveries with a view toward a potential development.

The wells have not been formation-tested, but extensive data and samples were collected. The wells are the second, third, fourth and fifth exploration wells in production license 248 F.

Wells 35/11-20 S and 35/11-20 A were drilled to respective measured depths of 3553 and 3943 meters below the sea surface and respective vertical depths of 3437 and 3293 meters below the sea surface. Both wells were terminated in the Heather formation in the Middle Jurassic.

The well 35/11-20 B was drilled to measured and vertical depths of 5083 meters and 4055 meters below the sea surface, respectively, and was terminated in the Statfjord group in the Early Jurassic.

Water depth at the site is 373 meters. The wells will now be permanently plugged and abandoned.

The drilling rig

Wells 35/11-19 S, 35/11-20 S, 35/11-20 A and 35/11-20 B were drilled by the Borgland Dolphin semi-submersible drilling rig.

Offshore Energy Today reported on Wednesday that the owner of the rig, Dolphin Drilling, reportedly announced a round of layoffs that would affect over 150 employees related to Borgland Dolphin rig.

Namely, the rig’s contract with Rig Management Norway, a consortium of four oil companies consisting of Wintershall, DEA, Tullow Oil and Suncor Energy, is set to expire in the fourth quarter of 2016.