2/4-17
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General information
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Wellbore history
GeneralThe Exploration well 2/4-17 was drilled on the NW Tor prospect situated in the Production License 018. The objective was to test the Late Jurassic and Early Permian sections in a rotated fault block on a terrace NW of the Tor Field. The block is situated in the Central Trough, which is part of the failed Mesozoic North Sea, rift system. The Central Trough comprises a complex series of narrow discontinuous highs and lows with a NW-SE trend. The most important basins are the Feda Graben, the Breiflab Basin and the Søgne Basin. From the Feda Graben/Breiflab Basin up to the Sørvestlandet High several rotated fault blocks form platforms and small highs, named the Cod Terrace, the Hitra High and the Steinbit Terrace. The NW Tor Prospect is situated on a Terrace between the Hitra High and the Feda Graben.Operations and resultsWildcat well was spudded with the 3-leg jack up installation on 29 February 1992 and drilled to TD at 5258 m in the Early Permian Rotliegendes Group. Drilling went without problems to 2081m were the well was sidetracked because the string became stuck while taking a survey. While pulling out of the hole, following the cutting core to a depth of 4357.1 m, an influx of gas occurred and the well was shut in. Following a 22 hours well kill operation, the well was brought back under control. A second technical sidetrack was taken at 4724 m due to a twist-off of the bottom hole assembly. The well was drilled with seawater/gel down to 466 m, with KCl mud from 466 m to 2146 m, with Soltex from 2146 m to 2582 m, with Soltex/Drispac from 2582 m to 4151 m, with HTHP mud from 4151 m to 4724 m, and with High Temp mud from 4724 m to TDTo thin hydrocarbon-bearing intervals were present in the Hod Formation. At 4340 m a major hydrocarbon bearing sand of the Late Jurassic Ula Formation was encountered. At 4520 to 5027 m an excellent quality aeolian dune sand of Early Permian age (Rotliegendes Group) was penetrated. The overall RFT pressure gradient in the sand showed water, but results in some intervals (e.g. 4600 m to 4650 m) suggested a different fluid (light hydrocarbons) from that shown by the logs (water). Post well organic geochemical analyses of a siltstone cuttings extract from 5029 m at the base of this unit indicated shows of hydrocarbons different from those of the Ula Formation. Further geochemical analyses of samples from this interval (5006 m to 5118 m) indicated source potential with TOC up to 2.9% and Hydrogen Index up to 190. The maturity level at this depth was measured as %Ro = 1.1 to 1.3, corresponding to the wet gas window. Because the 7" liner shoe was set at 5021 most of these samples must be seen as representative for the formation. The unit from 5027 m to TD was described generally as a "Rotliegendes mixed volcanic unit".One 60" core was cut in the lower Ula Formation, which consisted of major shallow marine sandstone, with marin silty sandstone in the base grading into thin lagoonal sand/silt/mudstone at the top. RFT pressures were taken during the logging of the 8 1/2 inch hole section. A segregated hydrocarbon sample at 4355 m was successful. However, measurement of the opening pressures revealed that the chambers hardly contained any gas, such that the samples were not representative of the reservoir fluid. Water samples were obtained at 4421 m and 4609 m.The well was completed on 29 February 1992 as a gas/condensate discovery.TestingTo DST tests were performed to investigate the to separate sand units. DST 1 in the Permian sandstone-unit (4523 - 4638 m) produced 860 Sm3 water/day. Samples taken from this test had a thin oil film on top of the water. DST 2 in the Upper Jurassic Lower Ula Formation (4341.0 - 4387.5 m) produced 774 Sm3 oil/day and 849510 Sm3 gas/day on a 15.875mm choke with a GOR of 1097 Sm3/ Sm3 -
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]475.505257.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom114235.014292.9[ft ]Cores at the Norwegian Offshore Directorate Total core sample length [m]17.6Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Oil samples at the Norwegian Offshore Directorate
Oil samples at the Norwegian Offshore Directorate Test typeBottle numberTop depth
MD [m]Bottom depth
MD [m]Fluid typeTest timeSamples availableDST4340.904387.5019.01.1992 - 20:00YES -
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 typeCONDUCTOR30204.036205.00.00LOTINTERM.20459.030460.01.62LOTINTERM.13 3/82133.017 1/22135.01.96LOTINTERM.9 5/84146.812 1/44148.02.17LOTLINER75021.08 1/25021.02.16LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0452346380.02.04341438815.92.1434043880.02.2434143880.02.3434143880.02.4434143880.02.5434143880.02.6434143880.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.01762.01602.12.22.32.42.52.6Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.02.07748490780.7990.73510972.12662.26102.35972.42.52.6 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CST00DLL BHC GR1361015350DLL MSFL BHC GR676613628DLL MSFL BHC GR1649017243DLL MSFL GR GPIT1361015350DLL MSFL NGL1361016485DLL MSFL SLS GR15087034FMS GR995013640FMS GR1361016485LDL CNL GR1361016498LDL CNL GR1649017257LDL NGL1649017257MSCT GR1024612901MWD67814235RFTB GR1023912898RFTB GR1424414423RFTB GR1428815132RFTB GR1483515384SDT NGL1361016484SHDT GR1649017181VSP170016350VSP300013025VSP940017250 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1101774305030503056309631183165318231923192333437294183418942834340434043894486448645184520 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.80 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf7.00 -
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]pdf81.35 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1921.03WATER BASED9031.1825.0WATER BASED13051.2623.0WATER BASED17951.5635.0WATER BASED18861.6250.0WATER BASED19361.8014.0WATER BASED19691.5036.0WATER BASED19961.6235.0WATER BASED20811.5636.0WATER BASED21461.6231.0WATER BASED22952.1232.0WATER BASED22952.1233.0WATER BASED23181.6726.0WATER BASED23771.8020.0WATER BASED25302.1232.0WATER BASED25601.7036.0WATER BASED26141.7020.0WATER BASED28481.7024.0WATER BASED29671.7122.0WATER BASED30391.7319.0WATER BASED31721.7328.0WATER BASED32691.7416.0WATER BASED33301.7427.0WATER BASED33841.7420.0WATER BASED35561.7525.0WATER BASED37231.7725.0WATER BASED37672.1231.0WATER BASED38891.7721.0WATER BASED39701.7721.0WATER BASED39701.7721.0WATER BASED41511.7715.0WATER BASED42402.1233.0WATER BASED42452.0428.0WATER BASED42502.1231.0WATER BASED42892.0633.0WATERBASED43072.1237.0WATER BASED43102.1232.0WATER BASED43142.0631.0WATER BASE43392.0834.0WATER BASED43532.1236.0WATER BASED43572.1028.0WATER BASED44212.1033.0WATER BASED44292.1050.0WATER BASED44322.1039.0WATER BASED44392.1228.0WATER BASED44392.1231.0WATER BASED44392.1238.0WATER BASED44952.1036.0WATER BASED45022.1036.0WATER BASED45122.1044.0WATER BASED45212.0647.0WATER BASED45262.1049.0WATER BASED45662.1027.0WATER BASED46232.1058.0WATER BASED46892.1036.0WATER BASED47172.1037.0WATER BASED47242.1032.0WATER BASED48032.1046.0WATER BASED49232.1048.0WATER BASED49622.0640.0WATER BASED50222.1034.0WATER BASED51151.9851.0WATER BASED51351.9839.0WATER BASED52582.1231.0WATER BASED