25/11-9
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General information
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Wellbore history
GeneralWell 25/11-9 was drilled ca km west-south west of the 25/11-1 Balder discovery well on the Utsira High in the North Sea. The objective was to establish the presence of a thick accumulation of oil sand in the southern part of the Balder Field, and to confirm the reservoir quality of Lobe 8 penetrated in the 25/11-5 well. The top of the reservoir was anticipated to be at 1688 m subsea.Operations and resultsAppraisal well 25/11-9 was spudded with the semi-submersible installation Norskald on 4 November 1980 and drilled to TD at 1910 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 560 m thick section of shale/mudstone/siltstone belonging to the lower Hordaland Group before top Balder Formation was encountered at 1670 m. Drilling revealed two oil sand zones, one of Eocene age between 1708.5 m and 1742 m (Intra Balder Formation sand), the second of Paleocene age (Hermod Formation) between 1781 m and 1785 m, which is the Balder Field oil-water contact. A few thin sands in the upper Balder Formation from 1671 m to1694 m also appeared to be oil bearing. A second Hermod Formation from 1789 to 1818 m was water wet with some weak shows.Four conventional cores were attempted in the interval 1718 to 1744 m in the Intra Balder Formation Sandstone, but only 3.5 m from the first and 1.5 m from the last core was retrieved. No wire line fluid samples were taken.The well was permanently abandoned on 7 December 1980 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]220.001910.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11718.01721.5[m ]41734.01735.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]4.5Cores 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 typeCONDUCTOR30213.50.00.00INTERM.13 3/8482.30.00.00INTERM.9 5/81207.50.00.00OPEN HOLE1910.08 1/21910.00.00 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CDL CNL GR11851909DIPLOG12081909DLL MLL GR11921909IEL BHC AC SP GR1501908SWC12501895SWC17181790VELOCITY1501909 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1516207457707709351000102210401045107711121670167017131741176817821783178918181825185518631882188718871902 -
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]pdf1.40pdf3.91 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1451.04waterbased3001.05waterbased4731.08waterbased8201.1146.0waterbased12001.09waterbased16931.1166.0waterbased -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1250.0[m]SWC1300.0[m]SWC1310.0[m]SWC1320.0[m]SWC1378.0[m]SWC1405.0[m]SWC1450.0[m]SWC1500.0[m]SWC1557.0[m]SWC1600.0[m]SWC1630.0[m]SWC1649.0[m]DC1661.0[m]DC1673.0[m]DC1679.0[m]DC1690.0[m]SWC1695.0[m]SWC1705.0[m]SWC1712.0[m]SWC1718.0[m]SWC1723.0[m]SWC1725.0[m]SWC1728.0[m]SWC1730.0[m]SWC1733.0[m]SWC1743.0[m]SWC1748.0[m]SWC1752.0[m]SWC1755.0[m]SWC1760.0[m]SWC1765.0[m]SWC1770.0[m]SWC1772.0[m]DC1778.0[m]DC1782.0[m]SWC1784.0[m]DC1787.0[m]SWC1790.0[m]SWC1790.0[m]DC1805.0[m]SWC1820.0[m]SWC1820.0[m]DC1825.0[m]SWC1826.0[m]DC1832.0[m]DC1835.0[m]SWC1838.0[m]DC1841.0[m]DC1845.0[m]SWC1847.0[m]DC1853.0[m]DC1855.0[m]SWC1859.0[m]DC1865.0[m]SWC1865.0[m]DC1870.0[m]DC1875.0[m]SWC1877.0[m]DC1885.0[m]SWC1889.0[m]DC1889.0[m]DC1895.0[m]SWC1901.0[m]DC1910.0[m]DC