2/7-4
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General information
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Wellbore history
GeneralWell 2/7-4 is located in the southern part of the Norwegian North Sea and ca 10 km south east of the Ekofisk Field. The primary objective was the Danian Chalk, expected to be 90 m thick and possibly completely hydrocarbon bearing.Secondary objective was Late Cretaceous carbonates, especially in the upper part, which could be oil bearing in communication with the Danian. Planned TD was at 3353 m in the Late Cretaceous. In the event that hydrocarbon shows were still evident at the proposed TD the well would be deepened until potential productive zones were completely penetrated.Operations and resultsWildcat well 2/7-4 was spudded with the semi-submersible installation Ocean Viking on 23 June 1972 and drilled to TD at 3356 m in the Late Cretaceous Tor Formation. The well was drilled without significant problems.The "Danian Chalk" (Ekofisk Formation) was encountered at 3096 m, and the Late Cretaceous Tor Formation at 3186 m. Both formations were oil bearing. DST's and logs indicate oil down to 3225 m, while the deepest test at 3291 - 3266 m produced water, some gas, and trace oil. Oil shows were recorded on cores in the interval 3133 m to 3246 m.Twelve cores were cut from 3116 m to 3264 in the Ekofisk and Tor Formations. No wire line fluid samples taken.The well was permanently abandoned on 3 September 1972 on as an oil discovery.TestingSix DST's were conducted in the Ekofisk and Tor Formations. Maximum production data after acid treatment follows: DST 1 tested the interval 3292 - 3266 m in the Tor Formation and produced 67 m3/day water, 2800 Sm3/day gas, and trace oil. DST 2 tested the interval 3197 - 3234 m in the Tor Formation and produced 1054 Sm3 oil and 273600 Sm3 gas /day on a 44/64" choke. The GOR was 260 Sm3/Sm3 and the oil gravity was 37.7 deg API. DST 3 tested the interval 3149 - 3170 m in the Ekofisk Formation and produced 200 Sm3 oil and 71200 Sm3 gas /day on a 36/64" choke. The GOR was 357 Sm3/Sm3 and the oil gravity was 44.5 deg API. DST 4 from the interval 3127 m to 3145 m in the Ekofisk Formation produced only water cushion: no formation fluid came to surface. DST 5 and DST 6 tested the interval 3106 m to 3114 m in the Upper Ekofisk Formation and produced small quantities of oil and gas to the surface from a nearly tight formation. -
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]487.683352.80 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom110224.010258.0[ft ]210258.010302.0[ft ]310302.010344.0[ft ]410359.010379.0[ft ]510380.010396.0[ft ]610405.010448.0[ft ]710448.010474.0[ft ]810477.010517.0[ft ]910517.010535.0[ft ]1010563.010580.0[ft ]1110605.010651.0[ft ]1210651.010679.0[ft ]Cores at the Norwegian Offshore Directorate Total core sample length [m]114.0Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory3174.5[m]COD3185.0[m]COD3185.6[m]COD3188.2[m]COD3190.3[m]COD3210.2[m]COD -
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 availableDST0.000.00YESDST0.000.00OILYES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit99174929452945296130083077309630963186 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.28 -
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]pdf18.33 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0326632920.02.0319732200.03.0314931700.04.0312731450.05.0310631140.06.0310631140.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.02.03.04.05.06.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.02.01054271833.020070794.05.077366.081444 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BHC4883351CBL10332429CBL23473242CBL23713326CDM24293355CDM AP PP12082438DL30483352FDC30613355GR1073351GR NL30183328IES4883356PML C30493356VELOCITY4883352 -
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 typeCONDUCTOR30177.036187.00.00LOTINTERM.20610.026622.01.86LOTINTERM.13 3/82093.017 1/22110.01.88LOTINTERM.9 5/83383.012 1/43390.00.00LOTLINER73710.08 1/23723.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1321.07seawater4871.31waterbased12191.4945.0waterbased24381.7147.0waterbased33531.7148.0waterbased