31/2-2
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General information
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Wellbore history
GeneralWell 31/2-2 was drilled some 4 km east of the discovery well 31/2-1 on seismic line 79-416 at SP 200. The concession requirement for the wells were complete penetration of the prospective Jurassic sequence and terminate in Triassic or older. The particular objectives of well 31/2-2 were: to evaluate lateral variation of reservoir parameters eastwards on the flank of the structure: to test the zone of oil shows seen in 31/2-1 in better reservoir conditions, to test the gas accumulation in a down-dip location: to evaluate the nature of the seismic flatspot, and to provide geological calibration of seismic reflectors above the reservoir for improved regional evaluation.Operations and resultsWell was spudded with the semi-submersible installation West Venture on 27 February 1980 and drilled to TD at 1857 m in the Middle Jurassic Krossfjord Formation. The 36" hole was drilled without incident to 433 m using seawater with viscous pills spotted on connections. From 422 m to 433 m hard drilling was experienced. This was interpreted as a boulder bed similar to that found at a comparable depth in the previous 31/2-1 well. Problems were encountered with the stability of the temporary guide base, and the well had to be abandoned. The rig was moved NE 25 m and re-spudded on 29 February. The well was drilled with seawater and hi-vis pills down to 800 m, and with gypsum/lignosulphonate mud from 800 m to TD.Top reservoir (Sognefjord Formation) came in at 1544 m and was gas bearing down to a gas/oil contact at 1579 m, and oil-bearing from 1579 m down to an oil/water contact at 1591 m. Both contacts were clearly defined on logs, the gas/oil contact was confirmed by RFT pressure gradients, and moveable oil was confirmed by RFT sampling at 1587.5 m and 1590 m. Gas samples were obtained from 1548 m and 1571 m. Weak oil shows began at 1561 m in the gas zone, strong shows with stained and bleeding cores and a paraffinic smell were observed in the oil zone. Oil shows ceased at 1602 m.Coring started at 1515 m in the Draupne Formation and terminated below the oil-water contact. A 120 m interval was cored with 94.2 m of core in 13 cores recovered at surface.After coring and logging of the Late Jurassic sandstones the well was suspended at the 9 5/8 casing shoe and the rig towed to Bergen for inspection and repairs on 22 April 1980.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]490.002600.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11515.01521.1[m ]21525.01527.0[m ]31535.01547.6[m ]41553.01560.0[m ]51560.01569.0[m ]61569.01578.0[m ]71578.01581.0[m ]81585.01598.0[m ]91598.01603.6[m ]101604.01606.4[m ]111608.01617.0[m ]121617.01626.0[m ]131626.01632.5[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]94.2Cores 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 typeCONDUCTOR30398.036400.00.00LOTSURF.COND.20768.026780.01.72LOTINTERM.13 3/81438.017 1/21448.01.64LOTINTERM.9 5/81817.012 1/41826.01.65LOTOPEN HOLE2568.08 1/22568.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL CCL GR7751825CBL GR CCL3541844FDC CNL GR CAL430797FIT15061506FIT15951595HDT14691855HDT18452590ISF BHC GR SP430809ISF BHC GR SP18002590LSS CTR18452590LSS GR14691855MSFL DLL SP CAL14691855RFC CNL GR CAL18002590RFT10RFT28VELOCITY00 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit35565065070311241124120513031374142414241431147014701545166517001848 -
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]pdf5.70pdf8.88pdf2.76pdf1.32pdf2.48pdf0.51pdf0.17pdf0.27pdf0.77pdf0.75pdf6.21pdf19.85pdf14.80pdf12.53pdf0.16pdf12.76pdf12.64pdf11.26pdf6.20pdf0.84pdf0.57pdf0.07pdf8.08pdf3.79pdf5.02pdf3.96pdf8.36pdf28.43pdf24.38pdf0.48pdf0.70pdf3.90pdf1.52pdf0.06pdf0.03pdf0.02pdf0.03pdf0.02pdf0.04pdf2.58pdf1.22pdf0.79pdf2.78pdf0.09pdf0.89pdf1.99pdf0.55pdf1.37pdf0.86pdf1.75pdf1.83pdf0.13pdf1.48pdf0.30pdf0.28pdf7.44pdf10.03pdf6.68pdf11.62pdf8.95pdf8.22pdf2.42pdf3.02pdf0.77pdf9.04pdf1.79pdf1.33pdf1.07pdf0.32pdf0.30pdf0.70pdf0.19 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured7081.2241.0seawater10001.2249.0seawater14081.2250.0seawater16241.2645.0seawater -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory870.0[m]DCGEOCH900.0[m]DCGEOCH930.0[m]DCGEOCH960.0[m]DCGEOCH990.0[m]DCGEOCH1167.0[m]DCGEOCH1203.0[m]DCGEOCH1233.0[m]DCGEOCH1263.0[m]DCGEOCH1287.0[m]DCGEOCH1317.0[m]DCGEOCH1347.0[m]DCGEOCH1377.0[m]DCGEOCH1398.0[m]DCGEOCH1428.0[m]DCGEOCH1455.0[m]DCGEOCH