30/11-4
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General information
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Wellbore history
GeneralWell 30/11-4 was drilled north-east of the Frigg area in the Fensal Sub-basin in the North Sea. Previous well 30/11-3 was abandoned at top Statfjord Group for technical reasons, due to high pressures, without being production-tested. Well 30/11-4 was then proposed as a virtual re-drill, only some 400 m NE of 30/11-3. The objective of the well was to test the hydrocarbon potential of the Middle Jurassic Vestland Group sandstones and the Early Jurassic Statfjord Group sandstones in a westward tilted horst blockOperations and resultsWildcat well 30/11-4 was spudded with the semi-submersible installation Dyvi Delta on 25 January 1984 and drilled to TD at 5255 m in Late Triassic sediments belonging to the Statfjord Group . At 2179 m the drill string parted, leaving a 24 m fish in the hole. After unsuccessful fishing the well was sidetracked from 1918 m. The well was drilled with bentonite and brack water down to 813 m, with KCl/polymer mud from 813 m to 4205 m, with gel/lignosulphonate/lignite mud from 4205 m to 5059 m, and with gel/polymer lignite mud from 5059 m to TD.Well 30/11-4 penetrated water bearing reservoir sands in the Tertiary Frigg and Heimdal formations. The Vestland Group was penetrated at 3434 m. This section had oil shows at 3434 m to 3470 m, where some oil emulsion was retrieved by RFT, at 3514 m to 3550 m, and at 3635 m to 3650 m. An anomaly in the reservoir pressure occurred at about 3580 m where a siltstone/claystone interval possibly acts as a seal/pressure barrier. A total of 615 m of sands and shales assigned to the Statfjord Group, between 4640 m and TD in the well. Log interpretation pointed towards the presence of at least 75 metres of sands with porosities up to 20% and water saturations as low as 40%. The Group had gas shows and weak oil/condensate shows on the cores. Subsequent microscopic studies on the cores, taken near to the top of the Group, have revealed that, although rather high porosities are locally preserved, permeability is destroyed by clay mineral authigenesis.Five cores were cut in the well. One was cut in the Vestland Group from 3514 - 3532 m. The remaining four were cut in the Statfjord Group in the intervals 4632 - 4649 m, 4652 - 4666 m, 4839 - 4839.4 m, and 5011- 5011.4 m. The two latter were junk basket cores. A depth shift of ca 10 m downwards has to be applied on the cores in order to match with logger’s depth. A segregated RFT fluid sample was taken at 3452 m in the Vestland Group. It contained water, gas, and oil emulsion.The well was permanently abandoned on 24 July 1984 as a dry well with shows.TestingThe Vestland Group was not considered worth testing. Two drill stem tests were performed in the Statfjord Group.DST 1 tested the interval 5015 to 5029 m. The test flowed only insignificant and non-representative fluids, even after acid stimulation. Extremely tight formation was concluded. Maximum temperature, measured at 5000.6 m, was 167 °C.DST 2 tested the intervals 4823 - 4837 m and 4854 - 4875 m. The test produced prior to acidization some 5 to 6 m3 formation water and some bubbles of gas over a period of 3 days at a flowing bottom hole pressure declining from 479 to 90 bar. After stimulation with 12 m3 acid the well produced 22 m3 water during 20 hours. The interval was concluded to be very tight. Maximum temperature, measured at 4809 m, was 162 °C. -
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]260.005255.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13514.03531.5[m ]24635.04645.7[m ]34652.04664.9[m ]44839.04839.4[m ]55011.05011.4[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]41.9Cores 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 typeCONDUCTOR30239.036250.00.00LOTSURF.COND.20796.026812.01.10LOTINTERM.13 3/82362.017 1/22375.01.79LOTINTERM.9 5/84192.012 1/44205.01.94LOTLINER75046.08 1/25059.02.09LOTOPEN HOLE5255.05 7/85255.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BGT GR7962330CBL VDL GR2482351CBL VDL GR10504202CBL VDL GR34285047CYBERLOOK23624202DLL MSFL GR23634200DLL MSFL GR46005058DLL MSFL GR50515220HDT30504200HDT42005062ISF BHC GR239812ISF BHC GR8122333ISF BHC GR23634202ISF BHC GR42015059ISF BHC GR42024846LDL CNL GR239813LDL CNL GR42024841LDL CNL GR46005059LDL CNL GR50515224LDL CNL NGS23204030NGS23204030RFT26073915RFT46445064RFT50735203SWC00VELOCITY05059 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1395141080198921602160219923452597261126112870315631933225326232623283343434343668401040104210427343194640 -
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]pdf2.73pdf15.08 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured5121.065.018.0WATER BASED8171.0716.013.0WATER BASED10191.0814.011.0WATER BASED13101.1016.016.0WATER BASED16941.0914.013.0WATER BASED20411.1014.014.0WATER BASED24601.2019.019.0WATER BASED38751.2524.019.0WATER BASED42051.26WATER BASED42191.30WATER BASED43101.35WATER BASED45631.5526.015.0WATER BASED46521.6024.014.0WATER BASED46921.5820.013.0WATER BASED48991.5923.016.0WATER BASED50691.5823.013.0WATER BASED50861.5627.015.0WATER BASED51951.5828.013.0WATER BASED -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory3517.6[m]CSPT3526.9[m]CSPT3529.6[m]CSPT -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit4657.10[m ]4635.80[m ]4642.30[m ]4660.70[m ]4839.00[m ]