ID: 293
OBJECTID: 293
wlbNpdidWellbore: 298
wlbName: 7/12-4
wlbHistory:

General

Well 7/12-4 was drilled as an appraisal well on the Ula Field in the North Sea. The main objective was to evaluate the extent and hydrocarbon potential of the Late Jurassic sands in the south eastern flank of the structure.

Operations and results

Appraisal well 7/12-4 was spudded with the semi-submersible installation Nordskald on 11 September 1977 and drilled to TD at 3623 m in Early Jurassic sediments of the Bryne Formation. Operations proceeded without significant problem. The well was drilled with fresh water/gel down to 498 m and with lime/Drispac mud from 498 m to TD.

The target reservoir Ula Formation was encountered at 3445 m, while the underlying Bryne Formation came in at 3529 m. Net sand in the reservoir was 73 m with porosity from 10 to 23%, permeability from a few millidarcy to 1750 millidarcy, and water saturation from 5 to over 60%. The reservoir was oil-bearing with a possible OWC at 3551 m in the Bryne Formation based on disappearance of oil shows; however, drill stem tests showed that the producible contact between oil and water was between 3530 and 3536 m.

Seven cores were cut from near top Ula Formation at 3447.5 m to 3556.7 m in the Bryne Formation. The recovery was 100% in core one to six and 96% in core seven. RFT fluid samples were taken at 3458 m (oil, emulsion and water), 3467 m (emulsion) and at 3528 m (water)

The well was suspended on 12 December 1977 for possible use as a producer at a later stage. It is classified as an oil appraisal well.

Testing

Production test
wlbHistoryDateUpdated: 2016-07-06T00:00:00