7120/1-4 S

General

Well 7120/1-4 S was drilled on the 7120/1-3 Gotha structure, situated on the southern end of the Loppa High in the Barents Sea. The discovery well 7120/1-3 found oil and gas in Late Permian karst carbonates of the Røye Formation. The primary objective of 7120/1-4 S was to test the reservoir properties and hydrocarbon potential of the Gohta Karst prospect. The secondary objective was to test the reservoir properties and hydrocarbon potential of a potential sandstone sequences in the Kobbe, Klappmyss and Havert formations.

Operations and results

Appraisal well 7120/1-4 S was spudded with the semi-submersible installation Island Innovator on 23 May 2014 and drilled to TD at 2520 m (2520 m TVD) in the Late Permian Røye Formation. No significant problem was encountered in the operations. The well was originally planned as an "S" shaped well. This was due to geological hazards connected to a deep-seated fault. Since TD was set 450 m shallow to plan, no deviation was necessary and the well became vertical despite the "S" denotation in the well name. The well was drilled with seawater and hi-vis pills down to 665 m and with Aquadril mud from 665 m to TD.

The well encountered blocky sandstones in the upper (764.5-802.5 m) Snadd Formation and thin sandstone beds in the lower Snadd target (interval 1200 to 1300 m), but the reservoirs proved water filled. The Kobbe and Klappmyss formations had no reservoir development. A 12.5 m thick mainly gas bearing conglomeratic sandstone unit (interval 2301-2313.5 m), was found at the Permo-Triassic boundary. This unit had pressure gradient almost identical to that of 7120/1-3, indicating a pressure communication between 7120/1-3 and 7120/1-4 S. Stratigraphic age is uncertain but i