15/12-12

General

The objective for well 15/12-12 was to test the hydrocarbon potential of the Rev structure in PL 038 approximately 5 km south-east of the Varg Field (Varg A Platform). The target level was Oxfordian Intra Heather Sands of the Viking Group.

Operations and results

Well 15/12-12 was spudded with the semi-submersible installation Scarabeo 6 on 25 December 2000 and drilled to TD at 3085 m in the Triassic Skagerrak Formation. At ca 2700 m the well starts to build angle up to a deviation of ca 25 deg at ca 2830 m. This deviation is kept down to TD where it leads to a difference between measured and vertical depth of ca 30 m. The well was drilled with seawater and hi-vis pills through to the base of the 17 1/2" section at 1384 m and with Glydrill KCL Polymer from 1384 m to TD.

A total of 121 m (2856 - 2977 m) gross Late Jurassic, Intra Heather reservoir sequence was penetrated in well 15/12-12 on the Rev Structure. The reservoir is interpreted as shallow marine sand bodies and is dated Oxfordian of age. On top of the reservoir lie 6 m sand dated Earliest Kimmeridgian of age. This sand was not considered as part of the net reservoir. The massive Intra Heather sands had very good reservoir quality. The cored interval of the reservoir had good hydrocarbon shows. Pressure data showed a clear gas gradient with a distinct GOC at 2954 m (2912 m TVD MSL) and an oil gradient down to base of reservoir (Top Triassic) at 2977 m (2932.5 m TVD MSL). MDT samples of the oil leg indicated an oil-down-to (ODT) situation. The pressure data also showed approximately 40 bars of depletion, caused by the production on the Varg Field (Southern Segment).

The interval between 2864 - 3000 m was cored in six cores, nearly the complete reservoir section and the upper part of Triassic. MDT fluid samples were taken throughout the reservoir at 2867.5 m, 2895 m, 2961 m, 2964.2 m, and 2972.5 m. Samples from the two deepest levels recovered varia