25/11-7
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General information
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Wellbore history
GeneralWell 25/11-7 was drilled ca 3 km west-south west of the 25/11-1 Balder discovery well on the Utsira High in the North Sea. The primary objective was to delineate topographic mounds developed in the Paleocene sands of the Balder Field. The primary targets were the Zone II sand (E-70 sand) which was found oil-bearing in the 25/11-5 and the Zone I-B sands which were found oil-bearing in the 25/11-6.Operations and resultsAppraisal well 25/11-7 was spudded with the semi-submersible installation Norskald on 3 October 1978 and drilled to TD at 1944 m in the Late Cretaceous Tor Formation. The well was drilled with Seawater/Gel/Lignosulphonate.The well penetrated the Utsira Formation and several Skade Formation sands and then penetrated a ca 600 m thick section of shales belonging to the lower Hordaland Group before top Balder Formation was encountered at 1697 m. The Balder Formation contained some shaley sands with poor to no oil shows. The massive I-B sand at 1750.3 m (Heimdal Formation) was the only significant oil sand in the well. The well proved 36 m of net oil sand with a clear oil-water contact at 1786.5 m (1761.5 m MSL), in reasonable agreement with the Balder Field contact at 1760 m MSL established in 25/11-6. The Zone II (E-70) sand was absent, or possibly an unrecognizable part of the I-B Sand.A total of 20.35 m core was recovered in four cores from the interval 1748.6 to 1772.3 m in the Lista and Heimdal Formations. No wire line fluid samples were taken.The well was permanently abandoned on 27 October 1978 as an oil appraisal well.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]1070.001945.30 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11748.61751.0[m ]21751.01753.0[m ]31753.01762.4[m ]41762.41772.3[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]23.7Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
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 typeCONDUCTOR30186.036186.00.00LOTINTERM.13 3/8396.017 1/2412.00.00LOTINTERM.9 5/81308.012 1/41325.00.00LOTOPEN HOLE1944.08 1/21944.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CAL13111845DLL MSFL15001945FDC CNL15001945GR149410HDT15001945ISF SONIC184410ISF SONIC3961316ISF SONIC13111944VELOCITY9301945 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit14959874276776792596097510551087166716671678169717011711171617511850186218751918192119211930 -
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]pdf1.28pdf100.03 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1860.00waterbased6941.08waterbased13251.06waterbased15311.11waterbased19441.13waterbased -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1090.0[m]DCCGG1110.0[m]DCCGG1150.0[m]DCCGG1190.0[m]DCCGG1220.0[m]DCCGG1300.0[m]DCCGG1350.0[m]DCCGG1360.0[m]DCCGG1370.0[m]DCCGG1380.0[m]DCCGG1400.0[m]DCCGG1430.0[m]DCCGG1440.0[m]DCCGG1450.0[m]DCCGG1460.0[m]DCCGG1470.0[m]DCCGG1480.0[m]DCCGG1490.0[m]DCCGG1560.0[m]DCCGG1580.0[m]DCCGG1600.0[m]DC1625.0[m]SWC1630.0[m]DC1638.0[m]SWC1652.0[m]SWC1655.0[m]DCCGG1659.0[m]SWC1665.0[m]DC1665.0[m]DCCGG1670.0[m]DCCGG1675.0[m]DCCGG1675.0[m]SWC1680.0[m]DCCGG1686.0[m]SWC1690.0[m]DCCGG1695.0[m]DC1698.0[m]SWC1700.0[m]DCCGG1705.0[m]DCCGG1705.0[m]DCCGG1710.0[m]DCCGG1715.0[m]DCCGG1717.0[m]SWC1720.0[m]DCCGG1725.0[m]DC1727.0[m]SWC1730.0[m]DCCGG1734.0[m]SWC1740.0[m]DCCGG1743.0[m]SWC1748.8[m]C1749.0[m]C1749.0[m]SWC1782.0[m]SWC1785.0[m]DC1803.0[m]SWC1815.0[m]DC1825.0[m]DCCGG1829.0[m]SWC1835.0[m]DCCGG1845.0[m]C1845.5[m]SWC1850.0[m]DCCGG1851.0[m]SWC1855.0[m]DCCGG1858.0[m]SWC1860.0[m]DCCGG1861.0[m]SWC1875.0[m]DCCGG1875.0[m]C1878.5[m]SWC1880.0[m]DCCGG1883.0[m]SWC1885.0[m]DCCGG1889.5[m]SWC1890.0[m]DCCGG1895.0[m]SWC1899.0[m]SWC1900.0[m]DCCGG1904.0[m]SWC1905.0[m]DC1908.0[m]SWC1914.0[m]SWC1918.0[m]SWC1920.0[m]DCCGG1925.0[m]DC1930.0[m]DC1940.0[m]SWC1945.3[m]C10000.0[m]C