7220/11-5 S

General

Well 7220/11-5 S was drilled to appraise the Alta oil and gas discovery on the Loppa High in the Barents Sea. The well was planned to drill horizontally through the Falk and Ørn formations oil leg in the Alta discovery. The objective was to demonstrate horizontal drillability through karstified and fractured carbonates using currently available technology. If successful, an extended test production was planned.

Operations and results

Appraisal well 7220/11-5 S was spudded with the semi-submersible installation Leiv Eiriksson on 6 April 2018. The well was drilled to TD in the 26” hole without significant problems. When installing BOP and riser the BOP suffered severe damage and 26.5 days were spent on repairs. After this drilling commenced without further significant issues. It was drilled vertical down to 1100 m, then building angle landing at 90° at 2375 m (1937 m TVD) in the oil leg in the Late Carboniferous Falk Formation. From this point it was drilled stratigraphically upwards from carbonates and heterolithics of the Falk Formation into younger carbonates of the Early Permian Ørn Formation. Well TD was set at 3057 m (1937 m TVD RKB) in the reef-type facies of the Ørn Formation. The well was drilled with seawater and hi-vis pills down to 478 m, with KCl/Polymer/GEM mud from 478 m to 794 m, with Performadril mud from 794 m to 2336 m, and with Baradril-N mud from 664 m to TD.

Base Triassic/top Falk Formation gas-filled carbonates was encountered at 1911 m (1787 m TVD). The well penetrated a 117-metre TVD gas column in the Carboniferous Falk formation, and a 720-meter horizontal section was drilled in the Falk and Ørn formation. The horizontal section is situated 32 metres under the gas-oil contact at 2161 m (1905 m TVD), and