15/12-11 S
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General information
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Wellbore history
GeneralExploration well 15/12-11 S was a joint operation of Production Licence 038 and 116. It was drilled in the northwestern area of block 15/12 and north of the Varg Field. Well 15/12-1 nearby to the northwest had shows in the Middle Jurassic Hugin Formation, but this was inconclusive with respect to moveable hydrocarbons. Block 15/12 is structurally located in the junction between the Jµren High to the southeast, the Ling Depression to the east, the Sleipner Terrace towards the north and the Witch Ground Graben to the west. The prospect was defined as a multi-target structure, situated on a rotated fault block. Primary targets were Tertiary sandstones of the Heimdal Formation in a genuine closure, in addition to sandstones of the Middle Jurassic Hugin Formation. Secondary high-risk targets were sandstones of Eocene, Late Jurassic and Triassic age.Operations and resultsExploration well 15/12-11 S was spudded with the semi-submersible drilling installation "Deepsea Bergen" on 10 April 1997 and drilled to TD at 3597 m (3464 m TVD RKB) in sandstones of the Triassic Skagerrak Formation. The well was drilled with seawater and hi-vis pills down to 407 m and with KCl / polymer / Glycol (ANCO 208) mud from 407 m to TD.Sandstone was encountered in all of the possible prospective levels except in the Late Jurassic. The two primary targets however, were more silt/shale dominated than expected. The upper part of the Heimdal Formation, penetrated at 2680 m had a lower reservoir quality than expected. These distal parts of the formation were relatively shaly/silty. More massive and porous sand of the Heimdal Formation was penetrated deeper, but too deep with respect to a Maureen Field oil spill. The lower reservoir, the Hugin Formation was penetrated at 3395 m, and was slightly thicker than prognosed. The only indications of hydrocarbons observed during drilling of 15/12-11 S were weak shows in the Hegre and Vestland Groups and a very weak cut fluorescence on the core from the Heimdal Formation. The gas values stayed constantly low during drilling through the reservoirs. Some gas peaks were measured while drilling the Hugin Formation, but these were associated closely to coal layers. Both the Heimdal and Hugin Formations were proved water bearing through wire line logging.A total of two cores were cut. The first coring recovered only 0.5 m from the Heimdal Formation (2724 m to 2724.5 m). The second coring recovered 18.6 m from the Hugin Formation (3399.4 m to 3418.0 m).Pressure tests were carried out in the Middle Jurassic Hugin and Sleipner formations and in the Triassic Skagerrak Formation. No fluid sample was taken.The well was permanently abandoned as a dry well with weak shows on 19 May 1997.TestingNo drill stem test was performed. -
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]410.002850.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12724.02724.5[m ]23400.03418.6[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]19.1Cores 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 typeCONDUCTOR30169.036170.00.00LOTSURF.COND.18 5/8394.026400.01.69LOTINTERM.13 3/81386.017 1/21390.01.85LOTINTERM.9 5/82879.012 1/42880.01.85LOTOPEN HOLE3597.08 1/23597.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]ARI MSFL LDL CNL GR AMS28793597FMI GPIT DSI NGT AMS28793597FMI GPIT GR AMS13862860FMI NGT DSI AMS13862866FMS GR ACTS28793597HALS PEX AMS13862866MDT ACTS GR33983570MDT GR ACTS33983570MDT GR AMS22742704MSCT GR23102695MSCT GR23102690MSCT GR27702810MSCT GR28182838MSCT GR28182842MSCT GR32293582MWD - GR RES DIR4072886MWD - GR RES DIR28863597VSP19103578 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1229671130132322702309253025302572261226802813282528402840285629223128314632213221323432413241332233953395341935443544 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.58 -
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]pdf3.16pdf34.47 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4071.04SPUD MUD6321.2623.0KCL MUD13951.3219.0KCL MUD14351.4224.0KCL MUD27261.4531.0KCL MUD28861.4531.0KCL MUD28881.4840.0KCL MUD30531.5141.0KCL MUD30911.5036.0KCL MUD32641.5036.0KCL MUD33171.5033.0KCL MUD33991.5328.0KCL MUD34001.5027.0KCL MUD34201.5027.0KCL MUD35971.5027.0KCL MUD