ID: 257
OBJECTID: 257
wlbNpdidWellbore: 262
wlbName: 2/7-3
wlbHistory:

General

Well 2/7-3, was drilled on the southern compartment of the Eldfisk structure in the North Sea. The Eldfisk structure is a NNW-SSE trending partly salt-related anticlinal structure located between the Valhall and Embla fields to the south and the Ekofisk Field to the north. The primary objectives were to test the Danian Limestone, and the possibility of Jurassic sandstone development on the crest of the Eldfisk structure. Both objectives were expected to be ca 120 m thick. The Late Cretaceous carbonate, lower Cretaceous sandstones and Triassic sandstones were secondary objectives.

Operations and results

Wildcat well 2/7-3 was spudded with the jack-up installation Orion on the 14 April 1972 and drilled to TD at 4359 m in the Permian Zechstein Group. Note that the Daily Report records Decca final fix as 56° 23' 01.7"N, 03° 14' 44.6"E, 60 meters off desired location, while other parts of the Completion Report seems to record the coordinates of the slightly different planned well location. The well was drilled with seawater and hi-vis sweeps down to 482 m, with gypsum-CMC lignosulphonate mud from 482 m to 3195 m, and with salt saturated gypsum-CMC lignosulphonate mud from 3195 m to TD. Between 482 m and TD diesel was added to the mud.

The Danian section was 90 m thick, highly fractured, and yielded commercial quantities of oil. Logs and two drill stem tests (DST 1 and DST 2) in the Late Cretaceous rocks indicated low porosity and permeability. One hundred and fifty gross meter of Jurassic sandstones was penetrated in the well. Log analysis indicated the sands are very shaly and silty. Three of the sidewall cores from this interval were described as hard, black shale and the fourth as a very calcareous sandstone. Although the logs
wlbHistoryDateUpdated: 2018-03-16T00:00:00