25/10-7 S
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General information
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Wellbore history
GeneralWell 25/10-7 S is located southwest of the Balder area. The primary objective of the well was to evaluate resource potential in the Paleocene Heimdal Formation in the Bjørn Prospect. Secondary objective was to evaluate resource potential in the Lower Eocene interval based on a high amplitude seismic response.Operations and resultsExploration well 25/10-7 S was spudded with the semi-submersible installation "Vildkat Explorer" on 20 May 1996 and drilled to TD at 2617 m (2582 m TVD) in the Early Paleocene Ekofisk Formation. The well was drilled with seawater and bentonite down to 1102 m and with "ANCOVERT" oil based mud from 1102 m to TD. The well was drilled deviated to avoid shallow gas at a depth of 512-822 meters below sea level close to the proposed location. The surface location of 25/10-7 S was moved approximately 200 m south of the reservoir target location, and no shallow gas was seen at this location. The well was drilled vertically to 1165 m where angle was gradually built to max 25.8 degrees and then again reduced to 1& at 2000 m. Well time for 25/10-7 S was 19.78 days (vs. 31 days targeted) for $4.7 M (vs. an AFE of $6.7 M). A major contribution to the reduced time and cost was a reduction of the electric logging program from the planned 4 days to the actual of 0.6 days due to a labour dispute involving key service companies in Norway. A 233 m thick Heimdal Formation was penetrated by the well, starting at 2238 m. The secondary, Eocene target was a 22 m thick limestone. The plan was to cut one core in the top of the Heimdal sand, regardless of hydrocarbon shows. Coring continued after core no.2 based on shows described at well site. A total of five cores were cut from 2200-2378 m from the Lista Formation through a complete Heimdal sequence and into the Lista Formation again. Subsequent to the coring MWD logs reamed across cored interval showed reservoir to be water wet. In the end onshore geochemical analyses identified the core "shows" as contamination from the mud. In addition to the MWD GR-AIT-LDT-CNL-Array Sonic and VSP was run. The wire line logs showed a dry hole. The work program also had SWC's and MDT pressures and one sample planned, but as the wire line logs confirmed a dry hole, it was decided to abort the planned program and plug the well. The well was permanently abandoned as a dry well on June 8, 1996.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]1110.002617.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12200.02230.3[m ]22232.02269.2[m ]32269.22306.7[m ]42306.72342.4[m ]52342.42380.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]178.3Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit142586726823823105611031125115311941526153815531632208620862122218622382373240424272465249825692569 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.49 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf1.76 -
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]pdf1.94pdf121.79 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]AIT AS LDT CNL GR10852592MWD - GR EWR4 DIR2502605VSP GR13702515 -
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 typeSURF.COND.30202.036203.00.00LOTINTERM.9 5/81085.012 1/41086.00.00LOTOPEN HOLE2617.08 1/22617.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured9851.3943.0OIL BASED11021.3732.0OIL BASED17100.1747.0OIL BASED22001.3743.0OIL BASED22300.1737.0OIL BASED22651.3941.0OIL BASED23061.3741.0OIL BASED23801.3834.0OIL BASED25041.3735.0OIL BASED25471.3836.0OIL BASED26171.3940.0OIL BASED