ID: 409
OBJECTID: 409
wlbNpdidWellbore: 414
wlbName: 33/9-9
wlbHistory:

General

Well 33/9-9 was drilled in the northern part of the Statfjord field, about 1.6 km southeast of 33/9-3 well on the Tampen Spur in the northern North Sea. The objectives were to provide structural and stratigraphic control on the Brent reservoirs, and to provide stratigraphic control and to establish an oil/water contact for the Statfjord reservoir.

Operations and results

Appraisal well 33/9-9 was spudded with the semi-submersible installation Borgny Dolphin on 27 July 1977 and drilled to TD at 3100 m in Late Triassic sediments in the Statfjord Formation. The well was drilled with seawater down to 486 m and with a seawater/lignosulphonate mud system from 486 m to 1993 m. At 1993 m, TD in the 17 1/2" section, the hole was displaced to a freshwater/Lignosulphonate mud system. At the same point diesel was added to free the 13 3/8" casing which had become differentially stuck. After that the mud contained initially 5% diesel decreasing to traces of diesel at to 2489 m. From 2489 m to final TD the freshwater/Lignosulphonate mud system was without measurable diesel.

No hydrocarbon shows were reported above the Brent Group. The Brent Group was found at 2413 m, 77.5 m deeper than prognosed 44.0 m thinner than anticipated in comparison to 33/9-3. Good oil shows were encountered at the top of the Brent Formation and continued throughout the reservoir down to top Dunlin Group at 2504 m. The entire Brent Group was oil-filled and it was above the field oil/water contact of 2609.1 m (2584.1 MSL). Log calculations showed that of the 87.0 m of gross oil section 84.6 m was net sand with 27.5% average porosity and 13.1% average water saturation. The Dunlin Group came in at 2504 m and log interpretation indicated a 23.2 m gross oil bea
wlbHistoryDateUpdated: 2016-07-06T00:00:00