ID: 378
OBJECTID: 378
wlbNpdidWellbore: 383
wlbName: 30/6-4
wlbHistory:

General

Well 30/6-4 was drilled on the Alpha structure on the Gullfaks fault block in the North Sea. The primary objective was to test hydrocarbon accumulations in Middle Jurassic sandstones and to define the hydrocarbon contacts. Gas was the expected hydrocarbon phase.

Operations and results

Well 30/6-4 was spudded with the semi-submersible installation Deepsea Saga on 17 February 1981 and drilled to TD at 2942 m in the Early Jurassic Amundsen Formation. Total depth for the well was reached 10 days before prognosed although 5 days were spent on rig repair when the heave compensator fell down. Apart from this accident no major problems were encountered in the drilling phase. The well was drilled in favourable weather condition. The well was drilled with spud mud down to 962 m, with KCl/polymer mud from 962 m to 1862 m, and with gel/lignosulphonate mud from 1862 m to TD.

Sporadic fluorescence was recorded on cuttings from limestone/siltstone stringers in the Paleocene and Cretaceous. Top Cretaceous had good shows on cuttings and sidewall core in the interval 2300 - 2305 m, and two valid RFT pressure points indicated a gas gradient over the interval.

Top Brent Group, Ness Formation was encountered at 2597 m with an oil-filled Etive Formation from 2630 m to 2686 m. No oil/water contact was found, but combined pressure data from the well and three previous wells on the structure indicated a gas/oil contact at 2528 m.

Four cores were cut from 2638 m in the Etive Formation to 2692.5 m, a few meters into the underlying Drake Formation. One RFT oil sample of good quality was taken at 2633 m.

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