34/10-37 A

General

Well 34/10-37 was drilled in the Tampen Spur area, ca 8 km WNW of the Gullfaks Sør Field. The results from 34/10-37 indicated a more complex fault pattern at the crest of the structure than expected and it was decided to drill a sidetrack.

The objective of the sidetrack, 34/10 - 37 A, was to investigate the presence of a low angle fault at the crest of the D-prospect, which could explain the missing sections of the Tarbert Formation in 34/10-37. The well was planned to penetrate the top of the Brent Group at a higher level than in 34/10-37 and terminate 50 m TVD below the oil-water contact in the Brent Group.

Operations and results

Appraisal well 34/10 - 37 A was kicked off through casing at 2049 m in well 34/10-37 on 22 February 1995 using the semi-submersible installation Deepsea Bergen. It was drilled to TD at 2950 m in the Middle Jurassic Ness Formation. No significant problems were reported from the operations. The well was drilled with KCl/PAC mud from kick-off to TD.

In addition to the formations encountered in 34/10-37 the well encountered the Rødby Formation, the Mime Formation and the Draupne Formation. Well 34/10-37 A penetrated the top of the Brent Group 15 m deeper than prognosed, but higher than in 34/10-37. An almost complete sequence of the Tarbert Formation was found in this well. The Brent Group proved to be hydrocarbon bearing with an "oil down to" at 2622 m TVD MSL.

Four conventional core were cut from 2664 m to 2741 m in the Tarbert and Ness Formations. No FMT samples were collected in the well.

The well was suspended on 3 April 1995 as an oil appraisal

Testing

The well was tested over the interval 2667 to 2697 m, and flowed with a rate of 1950 Sm3/day oil and 645000 Sm3/day gas (GOR = 330 Sm3/Sm3). The bottom hole temperature measured during the test was 97.2 deg C. A total of 4235 Sm3 oil was transferred to the vessel Crystal Sea an