ID: 283
OBJECTID: 283
wlbNpdidWellbore: 288
wlbName: 2/11-5
wlbHistory:

General

Well 2/11-5 was drilled on the western lobe of the Hod Field to test the Late Cretaceous Chalk section. The well was located 1.8 km SSE of 2/11-2 which tested oil from a very thin Chalk section of the Lower Hod Formation. Structural interpretations were made showing a NW-SE trending graben traversing the West Hod lobe. Based on a model from East Hod, it was expected that the porous Tor Formation should be preserved below the unconformity within this structure.

Operations and results

Well 2/11-5 was spudded with the semi-submersible installation Dyvi Alpha on 18 May 1979 and drilled to TD at 2945 m in the Early Cretaceous Rødby Formation. No significant problem was encountered in the operations, however six days were spent repairing the BOP stack before it could be run and two days were spent while mixing oil-based mud. The well was drilled with seawater, bentonite and CMC EHV down to 1285 m, with gyp/CMC mud from 1285 m to 2320 m, with lignosulphonate mud from 2320 m to 2765 m, and with oil based "Oilfaze" mud from 2765 m to TD.

The Paleocene Ash Marker (Balder Formation) was encountered at 2715 m; 105 m low to prognosis. The top of the Chalk Group, Ekofisk Formation was encountered at 2822 m; 117 m low to prognosis. In total, the Chalk section was found to be 98 m thick, whereas 300 m was predicted. These discrepancies reflect the effects of the shallow gas in the area on the seismic data. The velocity corrections which were applied to the seismic were too large. As a consequence, the Chalk Group within the Graben was found below the oil-water contact of the area and no moveable hydrocarbons were encountered. Frequent oil shows were reported however, starting in the upper part of the Hordaland Group:              
wlbHistoryDateUpdated: 2016-07-06T00:00:00