30/3-7 S

General

Well 30/3-7 S was drilled on the Veslefrikk Field, which is located due north of the Oseberg East Field. The objective of the well was to explore the hydrocarbon potential in the Brent Group, Intra Dunlin Sand and the Statfjord Formation in the B-prospect, west of the Veslefrikk horst.

Operations and results

Wildcat well 30/3-7 S was spudded from the fixed surface installation Veslefrikk A on 21 September 1995 and drilled to TD at 5581 m in the Lunde Formation. The 24" hole section from 467 m to 1472 m was drilled with Sea water/PAC converted to KCl/polymer mud. The 17 1/2" section from 1472 m to 2870 m was drilled with KCl/PAC/XANVIS mud, the 12 1/4" and 8 1/2" sections from 2870 m to 5581 m was drilled with Ancovert oil based mud.

The well drilled into the top of the Jurassic sequence earlier than expected, and hydrocarbon filled sandstones of unknown stratigraphy were penetrated almost 400 m higher than prognosed. The well was plugged back and a technical sidetrack was drilled and parts of the hydrocarbon filled interval was cored. Electric logs, core data, sidewall cores and paleo-dating as well as studies of the dip of layering and mineralogy, all show that the well penetrated several faults of varying throw. The stratigraphic intervals include both the Brent Group and the Statfjord Formation with several repeated and missing sequences. It soon became evident that the well never reached out to the B-prospect, but instead penetrated hydrocarbon bearing sandstones in several small fault blocks in the outskirts of the main Veslefrikk structure. A total of nine cores were cut, covering the base 2 m of the Heather Formation and ca 100 m of the faulted Brent sequence. RFT pressure points were recorded in the first Brent sequence (Tarbert/Ness) and in the second Brent sequence (Oseberg), but no fluid samples were taken on wire line.

The well was completed on 12 December 1995 as an oil/gas discover