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Exploration wellbore: 25/10-1

General information

Wellbore history

General

Well 25/10-1 is located in the western part of the Balder Field in the North Sea. It was drilled on the crest of an Eocene structure up dip from the 25/11-1 Balder Discovery well, which had thin, oil-bearing Lower Eocene sands underlain by wet Paleocene sands. The purpose was to test this structure, and it was anticipated that 25/10-1 would find the Paleocene sands structurally higher and oil-bearing.

Operations and results

Appraisal well 25/10-1 was spudded with the vessel Glomar Grand Isle on 4 August 1969. The pipe got stuck at 1572 m. Fishing was unsuccessful and a technical sidetrack was made. The well was drilled to 1747 m (TD) into Paleocene shale belonging to the Sele Formation, where it was plugged and suspended due to severe winter autumn storms. A later re-entry would complete the well objectives. Initial drilling from the set floor to 997 m was with sea water and gel. From 997 m to TD, the mud system consisted of seawater/spersene XP-20, Splinex mud.

Down to top Oligocene at 1247 m the sediments were composed of soft clays and unconsolidated sands and silts with no indication of hydrocarbons. The lower part of the well section (Early Eocene, Balder Formation) was predominantly grey shale with very thin sands developed below a volcanic ash zone near the base. These sands had good oil shows and tested 24.8 - 25.1 deg API gravity oil on wire line formation tests in the re-entry well 25/10-1 R, but were too thin to be considered commercial.

The section from 1664.8 to TD in this well was cored all through in eight cores, with near 100% total recovery. A further five cores in partially overlapping lithology, were cut in the re-entry well 25/10-1 R. No wire line tests were performed in this well, but a number of wire line FITs, including fluid sampling, were taken in the re-entry well.

The well was suspended on 16 October 1969. It is classified as a well with shows.

Testing

No drill stem test was performed.

Cuttings available at the NPD

Interval [m]: 385.57 - 1706.88

Cores available at the NPD

No cores in this wellbore.

Scanned core photos

5480-5487ft	5487-5497ft	5497-5508ft	5508-5517ft	5517-5526ft
5526-5537ft	5537-5549ft	5550-5560ft	5560-5572ft	5572-5584ft
5584-5596ft	5596-5605ft	5605-5613ft	5619-5628ft	4528-5636ft
5636-5645ft	5645-5453ft	5653-5662ft	5662-5671ft	5671-5680ft
5688-5696ft	5696-5705ft	5705-5713ft	5713-5719ft	5719-5727ft
5727-5733ft	5680-5687ft	5687-5696ft	5696-5705ft	5705-5714ft
5725-5732ft	5732-5741ft	5741-5750ft	5750-5756ft	5767-5776ft
5776-5785ft	5785-5794ft	5794-5797ft	5799-5859ft	5799-5859ft
5799-5859ft	5799-5859ft	5799-5859ft	5799-5859ft	5799-5859ft
5859-5919ft	5859-5919ft	5859-5919ft	5859-5919ft	5859-5919ft
5859-5919ft	5859-5919ft

Palynological slides available at the NPD

No palynological slides in this wellbore.

Oil samples available at the NPD

No oil samples available.

Casing and leak-off tests

Mud

Drill stem test

No drill stem test in this wellbore.

Available logs

Lithostratigraphy

Composite log

No composite log presently available.

Geochemical information available at the NPD

No geochemical data presently available. Regional geochemical studies which include data from this well may however be filed on a different well.

Documents reported by the licencees (period for duty of secrecy expired)

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Old NPD WDSS reports, NPD papers and other related documents

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