7120/6-2 S

General

Well 7120/6-2 S is an appraisal well on the Snøhvit Field in the Hammerfest Basin in the Barents Sea. The primary objective for the well was to prove that there are 36 MSm3 oil in place in the best reservoir zones where the oil is producible, in the Stø 2 and Stø 1 Formations. The well was also to confirm that the oil-water contact is located in the clean quartz sandstone at Stø 2 level in the Stø Formation. In addition, the assumed good quality and the thickening of the reservoir that was expected in the western part of the Snøhvit Field would be proven. A secondary objective for this well was to prove larger gas volumes in the western part of the Snøhvit Field than was calculated earlier.

Operations and results

Well 7120/6-2 S was spudded with the semi-submersible installation Polar Pioneer on 14 June 2007 and drilled to TD at 3242 m (3035 m TVD) in the Late Triassic Snadd formation. It was designed as an S-well in order to avoid shallow gas in the area and maintain stratigraphic/seismic control while drilling. The well started to build inclination from 470 m and reached maximum inclination of 32 deg in the interval ca 1600 to 2000 m in the 12 1/4" section. The hole packed of several times in the 17 1/2" section. This caused no significant delay in the drilling progress, but no logs were run in this section, from 932 - 1259 m. Formation tops in this section are based on the prognosis. No shallow gas was expected, and no shallow gas was observed. The well was drilled with sea water and bentonite down to 1259 m and with FORMPRO mud from 1259 m to TD.

The observed stratigraphy was well within the uncertainties given in the prognosis, with the exception of the Hekkingen Formation which was 16.5 m shallower than anticipated. Generally the difference from prognosis to result was within +/- 6.5 m and there were no trends in the discrepancies. The Stø Formation (target reservoir) was encountered at 2564 m (2371 m