16/3-5

General

Well 16/3-5 is an appraisal well on the southeaster part of the Sverdrup Field on the Utsira High in the North Sea. The objectives were to determine presence and thickness of the Late Jurassic Intra-Draupne Formation sandstone in a representative part of the Avaldsnes High (informal basement structure), and to investigate the reservoir properties of the Permian Rotliegend Group and Zechstein Group.

Operations and results

Appraisal well 16/3-5 was spudded with the semi-submersible installation Bredford Dolphin on 4 January 2013 and drilled to TD at 2050 m in the Permian Rotliegend Group. No significant problem was encountered in the operations. The well was drilled with seawater down to 700 m and with Performadril water based mud from 700 m to TD.

The well encountered top Draupne Formation shales at 1909 m and the Intra-Draupne Formation sandstone at 1918 m. The Draupne shales are immature but has very good source rock potential with TOC around 7-8 % and Hydrogen Index around 540 mg HC/g TOC. The Intra-Draupne sandstone is 14 m thick and rested on Permian Zechstein Group carbonates. An oil column of approximately 30 meters was found in the Intra Draupne Sandstone and Permian carbonate. The well proves an excellent development of the Late Jurassic sandstone in the southern part of the Avaldsnes High and the reservoir level was encountered a bit shallower than predicted. The Permian carbonates, mainly limestone, had varying reservoir quality with the best quality principally located in open and partially cemented vugs, plus in the fractures. The well results show an oil down-to situation and consequently no oil/water contact was encountered. The oil bearing Zechstein limestones are in pressure communication with the over