6507/11-5 S

General

The Midgard field is situated in the northeastern part of the Halten Terrace on a north south trending horst system, which is separated into 4 major segments. Four wells have been drilled on the Midgard Field, one in each of the segments Alfa, Beta, Gamma and Delta. Well 6507/11-5S was drilled as an appraisal well in the Gamma segment. The main objective of the well was to confirm the oil zone in the Ile Formation and to become a future gas producer on the Midgard field. The well should collect data on reservoir quality and fluid distribution related to both the oil and gas zones in the Midgard field.

Operations and results

Wildcat well 6507/11-5 S was spudded with the semi-submersible installation Deepsea Trym on 5 September 1997 and drilled to TD at 2695 m in the Middle Jurassic Ror Formation. Major operational problems were encountered leading to significant downtime. Firstly, one day was lost when the well drilled into shallow gas class II at 582 m. The well was killed and a cement plug was set. The 20" casing had to be set above the shallow gas zone. Second, fourteen days were lost due to heave compensator failures. Third, three days were lost when logging tools got stuck and failures on logging equipment appeared. The well was vertical down to 700 m where it built angle to 19.5 deg at 1350 m. This angle was kept down to TD. The well was drilled with seawater and hi-vis pills down to 547 m and with KCl/PAC mud from 547 m to TD.

The 6507 /11-5 S well proved 114 m TVD of gas and 11.5 m TVD of oil in the Fangst Group. This was deduced from FMT sampling and petrophysical evaluation of wire line logs. The GOC was found at 2605 m (2515 m TVD RKB) and the OWC at 2617.4 m (2526.5 m TVD RKB). Three wire line fluid samples were taken in Ile (FMT gas sample at 2592.9 m, RCI oil sample at 2608.3 m, and FMT water sample at 2622.1 m), and one in Garn (FMT gas sample at 2500 m).

The well was suspended on 28 October a