ID: 739
OBJECTID: 739
wlbNpdidWellbore: 1705
wlbName: 30/9-11 A
wlbHistory:

General

Well 30/9-11 A was drilled as a sidetrack to well 30/9-11 on the J-structure on the Oseberg Sør field in the North Sea.

The vertical 30/9-11 well drilled a dry Brent group in J-East segment. The sidetrack targeted the J-Central segment and should penetrate top of the Brent Group in a down flank position in order to confirm deep oil filling of the J-Central segment, where oil previously had been discovered by well 30/9-9. The primary target was the Brent Group. Secondary target was the Cook Formation.

Operations and results

Well 30/9-11 A was kicked off from 920 m in 30/9-11 on 20 November 1990. The well was drilled with the semi-submersible installation Vildkat to TD at 3002 m (2735 m TVD) in Early Jurassic sediments of the Statfjord Group. Apart from some tight hole problems and close to seven days wait on weather operations proceeded without significant problems. The well was drilled with KCl/polymer mud from kick-off to TD.

Top Viking Group, Heather Formation was encountered at 2513 m and top Brent Group, Ness Formation was encountered at 2553 m. The Ness Formation was water bearing, however moderate oil shows with strong petroleum odour was described on cores from top off the Ness Formation down to 2570 m. These shows were confirmed by relatively high organic geochemical extract yields with oil-mature biomarkers. Poor shows were described also in Shetland Group limestone from 2455 to 2457 m and in Heather Formation claystone from 2517 to 2520 m. Otherwise there were no indications of hydrocarbons in the well.

Three cores were cut in from 2545 to 2582 m in the Heather, Tarbert, and Ness Formation. A fourth core was cut fr
wlbHistoryDateUpdated: 2016-07-06T00:00:00