31/5-2
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General information
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Wellbore history
GeneralWell 31/5-2 is a replacement well for well 3/5-1 in the southern part of the Troll West Field. Well 31/5-1 was terminated at 860 m and junked due to an incident where the BOP and riser was lost. Due to this, the rig left the location and went to Bergen for repairs. It returned to the location five days later for drilling 31/5-2. The purpose of the well was to test the reservoir qualities, the oil/gas columns, and the hydrocarbon/water contact in the area.Operations and resultsAppraisal well 31/5-2 was spudded with the semi-submersible installation Treasure Saga on 5 October 1983 and was drilled to TD at 2500 m in the Late Triassic Hegre Group. A total of 5 days were lost on setting the 18 3/4" x 9 5/8" seal-assembly, otherwise no significant technical problems occurred in the operations. The well was drilled with seawater and hi-vis pills down to 860 m and with KCl/polymer mud from 860 m to TD.Well 31/5-2 penetrated top reservoir at 1521 m. The interval 1521 - 1569 m was gas bearing with 30% porosity and 15% water saturation. The interval from 1569 - 1582 m was oil bearing with 27% porosity and 30% water saturations. These intervals were the only hydrocarbon bearing intervals in the well. Between 1569 and 1582 m there were good shows in the cores. They showed brown oil stain, golden-yellow fluorescence and instant cloudy, milky, white cut. There was strong hydrocarbon odour.A total of six cores were taken in the interval 1505.0 -1599.9 m, covering the basal 16 m of the Draupne Formation and the upper 78 m of the Sognefjord Formation. The core recovery was 81%. FMT segregated fluid samples were taken at 1563 m (gas), 1575 m (oil at 135 bar), and 1581 (oil at 90 bar).After surveying, logging and sidewall coring, the well was plugged back to 1902 m and suspended on 11 November 1984. The well was to be re-entered at a later stage for testing.TestingNo drill stem test was performed -
Cuttings at the Norwegian Offshore Directorate
Cuttings at the Norwegian Offshore Directorate Cuttings available for sampling?YESCuttings at the Norwegian Offshore Directorate Cutting sample, top depth [m]Cutting samples, bottom depth [m]870.002500.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11505.01505.5[m ]21506.81521.9[m ]31524.81542.5[m ]41543.21570.4[m ]51570.51588.3[m ]61589.01601.4[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]90.8Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Casing and leak–off tests
Casing and leak–off tests Casing typeCasing diam.
[inch]Casing depth
[m]Hole diam.
[inch]Hole depth
[m]LOT/FIT mud eqv.
[g/cm3]Formation test typeCONDUCTOR30415.036418.00.00LOTSURF.COND.20848.026860.01.53LOTINTERM.13 3/81415.017 1/21430.01.63LOTINTERM.9 5/81952.012 1/41965.01.63LOTOPEN HOLE2500.08 1/22500.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]ACBL7931428ACBL12501965CDL CNL GR CAL8482492DIFL BHC LSBHC ACL GR8482495DLL MLL GR14151962FMT14151964FMT19522498HRD14152488SPECTRALOG14151955TEMP8211382 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit342670121012101286138214321432144114501450146514751475151615211642167418261908195720362036217621942225232323362393 -
Geochemical information
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Documents – reported by the production licence (period for duty of secrecy expired)
Documents – reported by the production licence (period for duty of secrecy expired) Document nameDocument formatDocument size [MB]pdf17.02pdf3.90 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured8941.1017.019.0WATER BASED12771.3420.020.0WATER BASED14351.2716.019.0WATER BASED20081.2313.016.0WATER BASED20881.2114.016.0WATER BASED23501.1713.016.0WATER BASED24671.2011.011.0WATER BASED -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory965.0[m]SWCIKU1182.0[m]SWCIKU1220.0[m]SWCIKU1250.0[m]SWCIKU1280.0[m]SWCIKU1290.0[m]SWCIKU1307.5[m]SWCIKU1421.5[m]SWCIKU1438.0[m]SWCIKU1465.0[m]SWCIKU1480.0[m]SWCIKU1485.0[m]SWCIKU1492.0[m]SWCIKU1499.0[m]SWCIKU1502.0[m]SWCIKU1604.0[m]SWCIKU1615.0[m]SWCIKU1633.0[m]SWCIKU1637.0[m]SWCIKU1645.0[m]SWCIKU1653.0[m]SWCIKU1665.0[m]SWCIKU1673.0[m]SWCIKU1682.0[m]SWCIKU1687.0[m]SWCIKU1693.0[m]SWCIKU1708.0[m]SWCIKU1717.0[m]SWCIKU1727.0[m]SWCIKU1737.0[m]SWCIKU1748.0[m]SWCIKU1753.0[m]SWCIKU1763.0[m]SWCIKU1774.0[m]SWCIKU1795.0[m]SWCIKU1806.0[m]SWCIKU1822.0[m]SWCIKU1825.0[m]SWCIKU1838.0[m]SWCIKU1853.0[m]SWCIKU1869.0[m]SWCIKU1874.0[m]SWCIKU1910.0[m]SWCIKU1917.0[m]SWCIKU1920.0[m]SWCIKU1935.0[m]SWCIKU1940.0[m]SWCIKU1948.0[m]SWCIKU1977.0[m]SWCIKU1982.0[m]SWCIKU1986.5[m]SWCIKU2011.0[m]SWCIKU2039.0[m]SWCIKU2053.0[m]SWCIKU2107.0[m]SWCIKU2115.0[m]SWCIKU2126.0[m]SWCIKU2135.0[m]SWCIKU2144.0[m]SWCIKU2153.0[m]SWCIKU2163.0[m]SWCIKU2171.0[m]SWCIKU2175.0[m]SWCIKU2186.0[m]SWCIKU2197.0[m]SWCIKU2205.0[m]SWCIKU2230.0[m]SWCIKU2333.0[m]SWCIKU2340.0[m]SWCIKU2358.0[m]SWCIKU2369.0[m]SWCIKU