25/2-21

General

Well 25/2-21 is the replacement well for 25/2-20, which was junked due to stuck pipe. It was drilled to test the shallow Liatårnet Prospect in the Fensal Sub-basin east of the Frigg Field in the North Sea. The primary objective was to prove hydrocarbons in the Early Miocene Skade Formation (“Liatårnet sand”).

Operations and results

Wildcat well 25/2-21 was spudded with the semi-submersible installation Deepsea Stavanger on 1 July 2019 and drilled to TD at 1200 m in the Late Oligocene sediments in the Hordaland Group. Operations proceeded without significant problems. The well was drilled with seawater and hi-vis pills down to 987 m and with KCl water-based mud from 987 m to TD.

Massive Utsira Formation sands were penetrated from at 280 m to 1012.5 m. An 11-meter thick claystone sequence capped the main Liatårnet sand, which was encountered at 1023.5 m. The Liatårnet sand was 28 m vertically thick and hydrocarbon bearing. The entire reservoir was cored and logged. Formation pressure tests in the sands gave a gradient range between 0.8 – 0.9 g/cc. The shallowest oil show in the well is described in thin sandstones at 1018 m, in thin sandstone stringers within the cap rock claystone over the Liatårnet sands. Strong oil shows with fluorescence, cut, stain and bleeding oil were seen throughout the Liatårnet oil-bearing sand to its base at 1052 m.

There were no shows below 1052 m. No fluid contacts could be established. A deeper sand penetrated from 1098 to 1010 m was water-bearing with a clear water gradient.

Three cores were cut. Core 1 was cut from 1024.8 to 1042.4 m with 96.3% recovery. Cores 2 and 3 were cut from 1042.7 to 1060