7/11-1
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General information
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Wellbore history
GeneralWell 7/11-1 was drilled on eastern side of the Breiflabb Basin in the southern North Sea, ca 3km from the UK Border. The main objective was to test the hydrocarbon potential of the Tertiary and the Mesozoic sediments. Specific objectives were Paleocene sandstone, the Late Cretaceous carbonate section, and the Jurassic. Sandstones in the Early Cretaceous and Triassic were seen as possible secondary targets.Operations and resultsWildcat well 7/11-1 was spudded with the semi-submersible installation Ocean Viking on 26 February 1986 and drilled to TD at 3974 m in Late Permian Zechstein Salt. The only significant drilling problem encountered was sloughing of shale between ca 1675 m and 2315 m. Deviation was negligible above 3500 m, from where it increased from 4.5 deg to 11.5 deg at approximately 3960 m. The true vertical depth therefore probably is 4-5 m short of measured depth at TD. A Drispac-Flosal-Desco mud system was used to a depth of 3290 m. At this depth the system was converted to a sodium chloride saturated Drispac-Flosal-Desco system. The salt saturated system was used to total depth.The well proved gas and condensate in three tests in a 5 m thick intra-Balder Formation sand (DST 5) and the Forties Formation from top at 2904 m down to 2989 m (DST 3 and 4). Below this depth DST 1 and 2 produced only minor amounts of hydrocarbons due to tight formation. Top salt came in under the Late Cretaceous Hidra Formation at 3740 m.Three cores were taken in the Paleocene sandstone in the intervals 2922.7 - 2932.8 m, 2932.8 - 2949.9 m, and 2952.9 - 2966.9 m. A fourth core at TD had no recovery. No wire line fluid samples were taken.The well was permanently abandoned on 15 June 1968 as a gas/condensate discovery.TestingFive drill stem tests were performed.DST 1 was performed from the interval 3124 to 3161 m. This test produced only diesel with "dark brown dissolved hydrocarbon".DST 2 was performed from the interval 3101 to 3108 m. This test produced 0.8 m3 oil in water out of 5 m3 in total.DST 3 was performed from the interval 2977 to 2989 m. The test produced 106 Sm3 condensate and 167000 Sm3 gas /day through a 5/8" choke. This corresponds to a Gas/Condensate Ratio of 1575 Sm3/Sm3. Reported reservoir temperature was 113 deg C.DST 4 was performed from the interval 2904 to 2956 m. The test produced 135 Sm3 condensate and 714000 Sm3 gas /day through a 3/4" choke. This corresponds to a Gas/Condensate Ratio of 5280 Sm3/Sm3. Maximum flow on variable chokes up to 2" was up to 430 Sm3 condensate and 1254000 Sm3 gas /day . Reported reservoir temperature was 110 deg C.DST 5 was performed from the interval 2877 to 2882 m. The test produced 76 Sm3 condensate and 184000 Sm3 gas /day through a 26/64" choke. This corresponds to a Gas/Condensate Ratio of 2412 Sm3/Sm3. Reported reservoir temperature was 109 deg 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]484.633962.40 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom19589.09618.5[ft ]29622.09644.0[ft ]39688.09701.0[ft ]Cores at the Norwegian Offshore Directorate Total core sample length [m]19.7Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit105152728682868288329043069317331733454370037033740 -
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]PDF1.68PDF6.31PDF8.71PDF3.97PDF0.11PDF0.36PDF0.15PDF1.06PDF2.87PDF4.40PDF3.14PDF5.72PDF10.12PDF2.71PDF0.50PDF0.87PDF0.69PDF1.22PDF1.19PDF1.02PDF0.14PDF0.40PDF1.81PDF1.36PDF17.09PDF2.82PDF9.24PDF1.61PDF1.59PDF0.07 -
Documents – Norwegian Offshore Directorate papers
Documents – Norwegian Offshore Directorate papers Document nameDocument formatDocument size [MB]pdf24.45pdf68.80pdf32.57pdf12.36 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0312431620.02.0310231096.33.02979298815.84.02904295619.05.02877288210.3Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.02.03.01134.01105.0109Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.02.03.010616700015754.013571400052805.0761840002412 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL21653124CCL27443128CDM4523970FDC19653970GR61452IES4523149LL31253970ML31253970MLL4523970SGR4523970SNP19653148VSP4523974 -
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 typeCONDUCTOR30141.036141.00.00LOTSURF.COND.20457.026463.00.00LOTINTERM.13 3/81965.017 1/21982.00.00LOTINTERM.9 5/83124.012 1/43145.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured01.1460.0waterbased12191.0740.0waterbased19811.1460.0waterbased24691.3950.0waterbased28961.4950.0waterbased31391.5550.0waterbased39741.4340.0waterbased -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit9500.00[ft ]9500.00[ft ]9510.00[ft ]9530.00[ft ]9560.00[ft ]9570.00[ft ]9590.00[ft ]9890.00[ft ]10150.00[ft ]9638.50[ft ]