31/2-5 R2

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

31/2-5 R2 is an appraisal exploration wellbore in the North Sea, drilled by A/S Norske Shell, entered Mar 22, 1984, 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
Mar 22, 1984: entered · completed Apr 22, 1984
Hegre Gp: at total depth · Triassic
—: m of core
79: °C bottom-hole temperature

SODIR FACTPAGES · RECORD UPDATED NOV 4, 2026 · RELEASED APR 22, 1986

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: 32
Kelly bushing elevation: 25 m
Maximum inclination: 1.5°
Drilling permit: 263-L3
Licensing round: 4
Plugged and abandoned: Apr 22, 1984
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 tested in the re-entry 31/2-5 R in 1981. The objective of the second re-entry was to test and quantify the water mobility (oil-water coning behaviour) in the aquifer zone underlying the oil column to provide input for the Field Development Plan of the Troll Field.

Operations and results

Wildcat well 31/2-5 R was re-entered (31/2-5 R2) with the semi-submersible installation Borgny Dolphin on 22 March 1984. The cement suspension plug (1261 m to 1450 m) was drilled out and a test was carried out.

The well was permanently abandoned on 22 April 1984.

Testing

A 3 m interval directly above the oil-water contact (1566-1569 m SS) was production tested. The test was conducted in three periods, a cleanup period (PT-2A), a period before acid treatment (PT-2B), and a period after acid treatment (PT-2C) The oil sample available from the NPD was sampled in PT-2B. The well produced up to 1002 Sm3 (6300 bbl) liquid /day. The water cut decreased in two days from high initial values (> 40%) to a stable value of 20%, independent of the liquid rate. The stable water cut was apparently controlled exclusively by the relative mobilities of oil and water. The rate dependence of the Productivity Index, significant before the acid job, almost disappeared after acidizing.

Around this wellbore

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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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