31/2-5 R

Exploration · Appraisal · Suspended · Oil/gas · A/S Norske Shell · Troll · PL 054

31/2-5 R is an appraisal exploration wellbore in the North Sea, drilled by A/S Norske Shell, entered Jun 12, 1981, to 2,525 m in the Hegre Gp.

Discovery 31/2-1 (Troll Vest) · On the map →

2,525: m total depth · 2,525 m vertical
333: m water depth
Jun 12, 1981: entered · completed Jul 20, 1981
Hegre Gp: at total depth · Triassic
—: m of core
79: °C bottom-hole temperature

SODIR FACTPAGES · RECORD UPDATED NOV 4, 2026 · RELEASED JUL 20, 1983

On file for this wellbore

What the Directorate holds from this wellbore. Each opens the section that lists it.

Drilling

Drilling facility: BORGNY DOLPHIN · Semisub steel
Drilling days: 39
Kelly bushing elevation: 25 m
Maximum inclination: 1.5°
Drilling permit: 263-L2
Licensing round: 4
Plugged and abandoned: —
Core samples available: No
Cuttings samples available: No
Position · ED50: 60.77117° N, 3.43152° E
Hydrocarbons in: Sognefjord Fm · Late Jurassic

Well history

WRITTEN BY THE NORWEGIAN OFFSHORE DIRECTORATE

General

Wildcat well 31/2-5 is located in the southern part of the oil province in the Troll West area, some 6 km west of the discovery well 31/2-1, in a downthrown fault block. It was drilled in 1980 and found a 21 m thick oil zone in excellent reservoir sandstone. The oil column in this location was found to be significantly thicker than in other wells in the area. The objective of the re-entry was to perform a production test in the oil zone.

Operations and results

Wildcat well 31/2-5 was re-entered (31/2-5 R) with the semi-submersible installation Borgny Dolphin on 12 June 1981. The cement suspension plug (1204 -1465 m) was drilled out and a test was carried out.

After testing a cement plug was set from 1261 m to 1450 m and again suspended on 20 July 1981.

Testing

One drill stem test was carried out. The oil zone was perforated from 1582 m to 1588 m and acidized to reduce impairment of the formation caused by completion fluids. The interval was then tested through gravel pack and produced 906 Sm3 (5700 bbl) oil /day on a 64/64" choke. The GOR was 53 Sm3/Sm3 and the oil gravity was 29 deg API. Opening up the choke to 2 x 64/64" the rate increased to 1177 Sm3 (7400 bbl)/day and the GOR increased to 243 Sm3/Sm3. Gas chromatographic analyses of the crude showed a bacterially degraded oil where the n-alkanes were almost absent.

Around this wellbore

This wellbore on Sodir FactPages →

About this data

Norwegian Offshore Directorate (Sodir) FactPages, mirrored nightly and used under the Norwegian Licence for Open Government Data (NLOD). Depths are metres along the wellbore from the kelly bushing unless a row gives its own unit; older cores are filed in feet. A zero the Directorate files for an unmeasured pressure, density, or temperature is shown as a dash.

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