2/7-2
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General information
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Wellbore history
GeneralWell 2/7-2 was drilled on the Grensen Nose structural element in the Central Graben of the North Sea. The primary targets for the well were Paleocene Sands and Danian Limestones; the secondary targets were Late Cretaceous carbonates, Early Cretaceous sandstones, Jurassic sandstones, and possibly Permo-Triassic sandstone reservoirs.Operations and resultsWell 2/7-2 was spudded with the semi-submersible installation Ocean Viking on 13 December 1970 and drilled to TD at 3964 m in the Early Permian Rotliegend Group. No significant technical problem was encountered in the operationsThe well was drilled with sea water and viscous slugs down to 594 m and with sea water, lignosulphonate, and 2 - 7 % oil from 594 m to TD.The well encountered the Late Paleocene Balder Formation at 2856 m, top Ekofisk Formation at 2966 m, and top Tor Formation at 3005 m. The Jurassic was encountered at 3862 m and consisted of 13 m Mandal Formation. Total organic carbon content in the Mandal Formation was 7-9 %, estimated to be of middle oil window maturity (vitrinite reflectance ca 0.75). The Mandal Formation rested directly on sandstones of the Rotliegend Group. Good oil shows decreasing to no shows were observed on cores 1 and 2 (3013.9 to 3027.9 m) in the Tor Formation. Otherwise no significant shows or other hydrocarbon indications were reported from the well.Three cores wore cut with 100% recovery. Cores 1 and 2 were cut from 3013.9 to 3027.9 m, while core 3 was cut in basaltic rock at TD from 3955.1 to 3963.6 m. No wire line pressures or fluid samples were taken.The well was permanently abandoned on 2 March 1971 as a minor oil discovery.TestingOne DST through perforations of the 9 5/8 inch casing was carried out with the following results:DST No. 1 perforated 4 shots per foot in the interval 3005.3 - 3017.5 m in the uppermost Tor Formation. The test flowed 6.83 m3 load water + 0.68 sm3 oil of 35.4 deg API gravity through a 1 inch choke. After acidization it flowed 54.6 Sm3 oil of 35.6 deg API gravity + 44.7 m3 formation water (35000 ppm chloride) and 4814 Sm3 gas through a 1 inch choke. The GOR was 88 Sm3/Sm3. -
Cuttings at the Norwegian Offshore Directorate
Cuttings at the Norwegian Offshore Directorate Cuttings available for sampling?NOCuttings at the Norwegian Offshore Directorate Cutting sample, top depth [m]Cutting samples, bottom depth [m]601.983959.35 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom19888.09904.0[ft ]29904.09934.0[ft ]312976.013004.0[ft ]Cores at the Norwegian Offshore Directorate Total core sample length [m]22.6Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit981478285628562871290529402966296630053194374337453752375237583791386238623875 -
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]pdf2.09pdf22.39 -
Documents – Norwegian Offshore Directorate papers
Documents – Norwegian Offshore Directorate papers Document nameDocument formatDocument size [MB]pdf72.88pdf0.54pdf0.56 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0300630180.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.0 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BHC GR5883962CBL943189DLL29273204FDC29273964GR91588GRN CCL27443093HDT28353207IES5873965ML MLLC29273208SNP28353209SRS913961 -
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 typeSURF.COND.30129.036129.00.00LOTINTERM.20587.026595.00.00LOTINTERM.13 3/81589.017 1/21604.00.00LOTINTERM.9 5/83189.012 1/43207.00.00LOTOPEN HOLE3965.08 1/23965.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1201.56waterbased5901.86waterbased16021.68waterbased32031.68waterbased -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit9885.00[ft ]9904.00[ft ]