25/8-12 S

Exploration · Appraisal · P&A · Oil · Esso Exploration and Production Norway A/S · Balder · PL 027

25/8-12 S is an appraisal exploration wellbore in the North Sea, drilled by Esso Exploration and Production Norway A/S, entered May 29, 1999, to 2,096 m in the Smith Bank Fm.

Discovery 25/8-11 Ringhorne · On the map →

2,096: m total depth · 2,085 m vertical
127: m water depth
May 29, 1999: entered · completed Jun 9, 1999
Smith Bank Fm: at total depth · Late Triassic
33.8: m of core in 1 core
82: °C bottom-hole temperature

SODIR FACTPAGES · RECORD UPDATED NOV 4, 2026 · RELEASED JUN 9, 2001

On file for this wellbore

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

Drilling

Drilling facility: MÆRSK JUTLANDER · Semisub steel
Drilling days: 12
Kelly bushing elevation: 23 m
Maximum inclination: 11.63000011°
Drilling permit: 954-L
Licensing round: 2-A
Plugged and abandoned: —
Core samples available: Yes
Cuttings samples available: Yes
Position · ED50: 59.28960° N, 2.44429° E
Hydrocarbons in: Hermod Fm · Paleocene
Hydrocarbons in: Statfjord Gp · Early Jurassic

Well history

WRITTEN BY THE NORWEGIAN OFFSHORE DIRECTORATE

General

Well 25/8-12 S was drilled to appraise the southern extension of the 25/8-11 discovery on the Ringhorn structure. In the Ringhorn structure, the BCU is also the base of the chalk and represents the overall top of the Lower Jurassic reservoir interval. The primary objective for 25/8-12 S was Lower Jurassic. Paleocene Hermod sands was a secondary target.

Operations and results

Appraisal well 25/8-12 S was spudded with the semi-submersible installation "Mærsk Jutlander" on 29 May 1999 and drilled to TD at 2096 m in the Triassic Smith Bank Formation. The well was drilled with sea water down to 990 m and with oil based mud ("Environment") from 990 m to TD. Top Hermod sands were encountered at 1785.1 m. They consisted of an upper thin sand and a lower massive sand. Several pressure points within the sands confirm a water gradient in the main sand (1790-1803 m). Elevated resistivity indicates hydrocarbons in the interval from 1787-1789 m (1756 - 1758 m TVD SS). Top Statfjord Formation was found at 1905.9 m. MDT data and other open-hole wireline data confirm oil down to (ODT) 1947 m (1914 m TVD SS), and water up to (WUT) 1959 m (1926 m TVD SS). This is consistent with the OWC of 1917.5 m TVD SS established in the 25/8-11 where it was penetrated within a massive sand. Seven MDT oil samples were collected at 1923 m, within the main Jurassic sand reservoir. Pressure was 187.5 bars and temperature (measured, not static) ranged from 80.2 deg C to 80.5 deg C during the sampling. One core was cut from 1905 m to 1941 m in the Statfjord Formation. Well 25/8-12 S was permanently plugged back to the 9 5/8" casing at 984 m on June 8 1999 for sidetrack 25/8-12 A. It is classified as an oil appraisal well.

Testing

No drill stem test was performed

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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