7220/11-3

General

Well 7220/11-3 was drilled to appraise the Alta discovery, about four kilometres south of discovery well 7220/11-1 and approximately 3 kilometres northeast of appraisal wells 7220/11-2 and 7220/11-2 A. The Alta discovery lie on the southern part of the Loppa High in the Barents Sea and comprises a structural trap with closures at the Permian-Triassic and Basement levels. The primary appraisal objectives were to confirm the presence of hydrocarbon columns and fluid contacts in a crestal position of the structure, and to test the reservoir properties of the Permian carbonates.

Operations and results

Appraisal well 7220/11-3 was spudded with the semi-submersible installation Island Innovator on 14 June 2015. During coring in karstified chalk and limestone at 1954 m, the core bit ran into a cavern of unknown size. The string suddenly dropped 2 meters with no WOB. Total fluid losses occurred at a loss rate of 60 m3/hr. The well was shut in with seawater in the annulus and a full well control incident occurred. The drill string was shot-off, leaving the core barrel in the hole. The main bore was drilled with seawater and hi-vis pills down to 598 m and with Aqua-Drill mud from 598 m to 1956 m, which became TD. The main wellbore was plugged back to the 13 3/8" casing shoe and a technical sidetrack, 7220/11-3 T2, was kicked off from 1087 m to secure missing data. The sidetrack was drilled to a total depth of 1922.5 m (1920 m TVD) in the Permian Ørn Formation. The technical sidetrack well 7220/11-3 T2 was drilled with Aqua-Drill mud from kick-off to TD.

Well 7220/11-3 encountered a 75-metre thick gas column and the upper part of an oil column in carbonates in the Gipsdalen Group of good to very good reservoir quality. The reservoir