7/1-2 S

General

The 7/1-2 S Yoda well is located on the north-western margin of the Jæren High, 18 km southeast of the Varg field and 5.5 km northeast of the closest well 6/3-2. The well is located on a 4-way dip closure over a salt wall similar to the Rev discovery 13 km northwest of Yoda. The primary objective of the well was to prove commercial hydrocarbons in the Late Jurassic Ula Formation sandstones. The secondary objective was to test the Triassic prospectivity.

Operations and results

Well was spudded with the jack-up installation Mærsk Giant on 20 March 2008 and drilled to TD at 3175 m in the Middle Jurassic Bryne Formation. It was drilled slightly deviated in an S-shaped track, vertical down to ca 1600 m and below ca 2400 m with maximum deviation of 16 deg from vertical at 1893 m. Whilst drilling the 17 1/2" section from 592 to 1320 m the hole produced significant amounts of large, blocky cavings, but there were no real problems encountered during operations. The well was drilled with seawater down to 201 m, with Aquadril glycol/KCl mud from 201 to 1320 m, and with Carbo-Sea oil based mud from 1320 m to TD.

The Mandal Formation was encountered at 2848 m and was 71 m thick with very high gamma ray responses varying between 150 and 300 API. The top of the reservoir, Ula Formation, was encountered at 2945 m, 16 m shallower than prognosed, and 14 m thicker than prognosed. No shows were observed in cuttings and gas and the resistivity remained low throughout the Ula Formation indicating a water wet reservoir. The rock below the Ula Formation reservoir was prognosed to be the Triassic Skagerrak Formation. However, it turned out to be the Middle Jurassic Bryne Formation. As a result the well was TD?ed in the Bryne Formation and not a