2/7-7
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General information
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Wellbore history
GeneralWell 2/7-7, was drilled to appraise the southern part of the Eldfisk structure in North Sea. The primary objective was to test the Danian Limestone, expected to be about 120 m thick.Operations and resultsAppraisal well 2/7-7 was spudded with the semi-submersible installation Ocean Viking on 2 January 1973 and drilled to TD at 3084 m in the Early Cretaceous Rødby Formation. The well was drilled with seawater and hi-vis sweeps down to 497 m and with gypsum/lignosulphonate mud from 497 m to TD. 4-6% diesel additive was used below 497 m.The Danian Limestone was found to be highly fractured, only3 0 m thick, and yielded commercial quantities of oil and gas on one drill stem test. The Late Cretaceous, which was 195 m thick, was also found to contain hydrocarbons, and yielded commercial amounts of oil and gas on two out of three drill stem tests. The Danian Limestone and the upper part of the Late Cretaceous were thinner than expected due to a fault throwing Campanian on Turonian rocks.No cores were cut and no fluid samples were taken.The well was permanently abandoned on 29 March 1973 as an oil appraisal.TestingFour intervals in the chalk section were perforated and testedDST's 1 and 2 tested the interval 2911 to 2925. The interval gave a weak flow with headed oil + gas. The oil gravity was measured to 36.2 °API.DST 3 tested the interval 2838 to 2905 m. The interval produced after acidizing 977 Sm3 oil and 387900 Sm3 gas /day through a 1.5 " choke. The GOR was 397 Sm3/Sm3, the oil gravity was 36.8°API, and the gas gravity was 0.7078 (air = 1).DST's 4 and 5 tested the interval 2827 to 2833 m. The interval produced after acidizing 1024 Sm3 oil and 443400 Sm3 gas /day through a 1.5 " choke. The GOR was 433 Sm3/Sm3 and the oil gravity was 37°API.DST 6 tested the interval 2789 to 2822 m. The interval produced after acidizing 1179 Sm3 oil and 497800 Sm3 gas /day through a 1.4" choke. The GOR was 422 Sm3/Sm3, the oil gravity was 35.8°API, and the gas gravity was 0.6883 (air = 1).DST 2 (2911 to 2925 m) and DST 4 (2827 to 2833 m) were misruns due to leaks. -
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]518.163081.53 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit9716022677267726882723276927922792282228292963296730183018 -
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]pdf1.24pdf16.46 -
Documents – Norwegian Offshore Directorate papers
Documents – Norwegian Offshore Directorate papers Document nameDocument formatDocument size [MB]pdf72.88pdf0.82pdf0.56 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0291129250.03.02838290538.05.02827283338.06.02789282238.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.03.05.06.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.03.09764156914265.010455181934966.01179526693447 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BHC4873072CBL22862916CBL23472950CBL23472804CBL25912835CCL29052954CDM24263078CNL25912954FDC27433048FDC CNL27433048GR97487IES4873082ISF12192439ML MLL27433048VELOCITY4813072 -
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 typeCONDUCTOR30133.036133.00.00SURF.COND.20487.026497.00.00INTERM.13 3/81219.017 1/21232.00.00INTERM.9 5/82428.012 1/42439.00.00OPEN HOLE3085.08 1/23085.00.00 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1301.07seawater4881.37barite24381.71barite30801.73barite