2/5-8
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General information
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Wellbore history
GeneralWell 2/5-8 is located on the South East Tor Field in block 2/5 in the Central Trough in the North Sea. The overall outline of the field had previously been defined by the wells 2/5-3 and 2/5-5. The purpose of the well was to test the distribution of high-porosity, re-deposited chalk and productive zones west of the major NS trending crestal fault in the field. It was also planned to test the productivity of the chalk in both the Ekofisk and the Tor Formations on the flanks, confirm reserve calculations for the structure and get good oriented core coverage in both formations.Operations and resultsAppraisal well 2/5-8 was spudded with the semi-submersible installation Dyvi Stena on 18 September 1988 and drilled to TD at 3367 m in the Late Cretaceous Hod Formation. Drilling proceeded without significant problems. The well was drilled with seawater and pre-hydrated gel sweeps down to 370 m and with water based gypsum/polymer non-dispersed mud from 370 m to TD.Top Ekofisk came in at 3107 m and top Tor Formation at 3204 m. Two cores were cut in the interval 3115 - 3142.5 m in the Ekofisk Formation and another three cores in the interval 3207 - 3291 m in the Tor Formation. The chalk was of a relatively poor reservoir quality both in the Ekofisk and Tor Formation, and oil staining were only found along fracture planes in cores from the Tor Formation. The logs confirmed the negative result from the cores.No fluid samples were taken in the well.The well was permanently abandoned on 5 November 1988 as a dry well with shows.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]390.003365.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13115.03130.0[m ]23130.03142.0[m ]33207.03234.9[m ]43235.03263.0[m ]53262.03291.3[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]112.2Cores 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 typeCONDUCTOR30139.036166.00.00LOTSURF.COND.20359.026373.01.50LOTSURF.COND.20360.026373.01.50LOTINTERM.13 3/81582.017 1/21598.01.93LOTINTERM.9 5/83006.012 1/43017.01.92LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL GR CCL11002983CST GR30103360DIL BHC GR CAL15783013DIL SFL BHC GR30043366DLL MAFL GR30043368FMS GR30033368LDT CNL GR30043368MWD - GR RES DIR1463199RFT GR31113290VELOCITY16603365 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit921898295329532973304230903107310732043323 -
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]pdf31.95 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1461.0612.0WATER BASED3701.0312.0WATER BASED9871.2517.0WATER BASED15951.4329.0WATER BASED18601.6220.0WATER BASED21451.6221.0WATER BASED23001.6221.0WATER BASED27281.6221.0WATER BASED30171.6320.0WATER BASED31241.6223.0WATER BASED32531.6232.0WATER BASED33561.6232.0WATER BASED33670.00WATER BASED