7/8-2
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General information
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Wellbore history
The 7/8-2 (Cero) well was drilled on a domal structure approximately 6 km long by 6 km wide, situated on the Jæren High in the North Sea. It was estimated that at Paleocene depth there would be close to 40 square km of closure with 140 m of vertical relief and at Early Cretaceous depth 27 square km of closure with 150 m of vertical relief. The principal objective horizons were Paleocene, Jurassic and Triassic sands with the Danian-Cretaceous limestone as a possible secondary objective.Operations and resultsWildcat well 7/8-2 was spudded with the semi-submersible installation Ocean Viking on 24 July 1973 and drilled to TD at 3006 m in anhydrite of the Zechstein Group. No significant problems are reported from the operations.The well had no hydrocarbons or shows of hydrocarbons. In the Paleocene no sand beds were developed, although sand was present as a loose, unconsolidated constituent in most of the clays and shales. The Danian and Late Cretaceous limestones were tight. The Late Cretaceous section was 150 m thinner than anticipated due to erosion of the Coniacian to Cenomanian formations at the base. The Jurassic succession was encountered at 2808 m and top Triassic at 2883 m. Two Triassic sands were encountered at 2911 - 2937 m and at 2972 - 2996 m. The Triassic section was thinner than expected, being truncated at 2996 by the Permian Zechstein Group.No cores were cut and no wire line fluid samples were taken in the well.The well was permanently abandoned on 29 August 1973 as a dry well.TestingNo drill stem test was performed. -
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]1237.493006.24 -
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 typeCONDUCTOR30142.036142.00.00LOTSURF.COND.20437.026450.00.00LOTINTERM.13 3/81209.017 1/21219.00.00LOTINTERM.9 5/82243.012 1/42255.00.00LOTOPEN HOLE3006.08 1/23006.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BHC4381215BHC-C12142256BHC-C22442931BHC-C28963005CDM22442931CDM AP22442931CDM PP22442931CDR22442931FDC23472992GR98438IES4381215IES12112259IES22442930IES28963006VELOCITY4383006 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit10814632180218021952295236623662440265728082822288328832997 -
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]pdf3.81pdf0.85 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1501.07seawater12201.1345.0seawater22501.5550.0waterbased30001.5555.0waterbased -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory9160.0[ft]CRRI9190.0[ft]CRRI9220.0[ft]CRRI9250.0[ft]DCRRI9280.0[ft]DCRRI9310.0[ft]DCRRI9340.0[ft]DCRRI9360.0[ft]DCRRI9390.0[ft]DCRRI9420.0[ft]DCRRI9460.0[ft]DCRRI9470.0[ft]DCRRI9490.0[ft]DCRRI9510.0[ft]DCRRI9530.0[ft]DCRRI9550.0[ft]DCRRI9570.0[ft]DCRRI9610.0[ft]DCRRI -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit9130.00[ft ]