30/6-26

General

Well 30/6-26 was drilled on the Gamma West structure on the western flank of the Oseberg Field in the North Sea. The purpose of the well was to prove oil and gas in the Early Jurassic Statfjord Group.

Operations and results

Wildcat well 30/6-26 was spudded with the semi-submersible installation Transocean Arctic on 15 September 2001 and drilled to TD at 2865 m in the Early Jurassic Statfjord Group. The well is classified as vertical, but from 300 to 800 m in the 17 1/2" section the deviation from vertical was up to 10.8 deg. Due to this the measured depth below 800 m is ca 5.5 m short of vertical depth. The well was drilled with sea water and hi-vis pills down to 1212 m and with Versavert oil based mud from 1212 m to TD.

Top Statfjord Group was encountered at 2668 m. A 29 m gas column and a 43 m oil column were proven in the Upper Statfjord Group. The gas-oil-contact is interpreted at 2697 m (2692 m TVD) and the oil-water contact at 2741 m (2735 m TVD). The oil-bearing part of the Statfjord Formation has excellent reservoir properties. The oil zone is divided in two parts by a marine shale, which represents a ca 1.2 bar pressure barrier in the oil zone penetrated by the well. The Lower Statfjord Formation was water-bearing. Fluid samples confirmed the fluid types. No oil shows were described outside of the petroleum-bearing reservoir.

One 28 m core was cut in the Upper Statfjord Formation from 2690 to 2718 m, with 98.9% recovery. The MDT wire line tool was used for formation pressure testing and fluid sampling. Twenty-five good pressure points were acquired. Fluid sampling was performed at 2772 m (water), 2735 m (oil), 2716 m (oil) and 2669 m (gas).

<p cl