25/10-4
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General information
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Wellbore history
GeneralThis well was drilled in two phases, a primary well bore 25/10-4, and a re-entry well bore 25/10-4 R. The well was drilled in the western part of the Balder Field in the North Sea. The primary objective was to establish the presence of a thick accumulation of Paleocene oil sand, and evaluate sand-shale distribution and reservoir quality. The top of the reservoir was anticipated to be at 1698 m subsea. As a secondary high-risk objective, the well was to be drilled to 2700 m to test for the presence of hydrocarbons in the Permian. This test was necessary as any hydrocarbons present could critically affect the design and location of a possible production platform.Operations and resultsAppraisal well 25/10-4 was spudded with the semi-submersible installation Glomar Biscay II on 8 December 1980 and drilled to TD at 2348 m in the Late Permian Zechstein Group where the well was suspended due at 18 January 1981 due to a pressing need for the rig to drill other Balder Field delineation wells, combined with unexpected delays in the 25/10-4 well progress as a result of lost circulation. The re-entry commenced on 29 May 1981 and deepened the well to 2550 m in a massive unconsolidated sand of Permian/ Carboniferous age. The top hole down to 30" casing depth at 214 m was drilled with seawater. Below 214 m the well, including the re-entry well, was drilled with seawater/gels/lignosulphonate.The main oil sand of Paleocene age was encountered between 1759.5 m and 1784.0 m. The net oil sand was 22 m thick. The Triassic section had several thin and oil-bearing sandstones not detected before in the area. A wire line FIT in one of these sands proved live oil. In total these sandstones made up 21 m net sand but the accumulation was considered insignificant. Cuttings from 2130 m (Early Jurassic) through Permian Zechstein and the upper part of the Permian/Carboniferous unconsolidated sandstone contained traces/shows of hydrocarbons.No cores were cut. A wire line FIT at 2226 m in a thin Triassic sandstone recovered 7500 cm3 oil with some mud.The well was permanently abandoned on 13 June 1981 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?NOCuttings at the Norwegian Offshore Directorate Cutting sample, top depth [m]Cutting samples, bottom depth [m]220.002350.00 -
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 typeCONDUCTOR30214.036214.00.00LOTINTERM.13 3/8497.017 1/2512.01.68LOTINTERM.9 5/81288.512 1/41305.01.71LOTLINER72279.08 1/22349.01.63LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]DEN NEU12722348DLL MLL16001949IEL AC GR SP1502343TEMP4511245 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit151569693740740920105811091203121914181487168216821720174717601874195019611961196319821985200321542314 -
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]pdf1.60pdf20.29pdf14.19 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4601.1035.0seawater7301.0851.0seawater11601.0738.0waterbased14501.1239.0waterbased17501.1044.0waterbased19101.1548.0waterbased21201.2051.0waterbased -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1150.0[m]DC1180.0[m]DC1210.0[m]DC1240.0[m]DC1270.0[m]DC1300.0[m]DC1330.0[m]DC1360.0[m]DC1390.0[m]DC1420.0[m]DC1450.0[m]DC1480.0[m]DC1510.0[m]DC1540.0[m]DC1570.0[m]DC1600.0[m]DC1620.0[m]DC1620.0[m]DCRRI1630.0[m]DCRRI1640.0[m]DCRRI1640.0[m]DC1650.0[m]DC1650.0[m]DCRRI1660.0[m]DCRRI1660.0[m]DC1670.0[m]DCRRI1675.0[m]DCRRI1678.0[m]DC1684.0[m]DCRRI1687.0[m]DC1696.0[m]DC1696.0[m]DCRRI1702.0[m]DC1705.0[m]DC1705.0[m]DCRRI1708.0[m]DC1711.0[m]DC1714.0[m]DC1717.0[m]DC1720.0[m]DC1720.0[m]DCRRI1723.0[m]DC1726.0[m]DC1729.0[m]DC1729.0[m]DCRRI1732.0[m]DC1738.0[m]DC1744.0[m]DC1744.0[m]DCRRI1750.0[m]DCRRI1750.0[m]DC1759.0[m]DCRRI1771.0[m]DC1790.0[m]DC1810.0[m]DC1830.0[m]DC1850.0[m]DC1870.0[m]DC1870.0[m]DCRRI1890.0[m]DC1900.0[m]DCRRI1910.0[m]DC1930.0[m]DC1950.0[m]DC1960.0[m]DC1970.0[m]DC1980.0[m]DC1980.0[m]DCRRI1990.0[m]DCRRI1990.0[m]DC2000.0[m]DC2000.0[m]DCRRI2010.0[m]DC2020.0[m]DC2050.0[m]DC2070.0[m]DC2090.0[m]DC2110.0[m]DC2130.0[m]DC2150.0[m]DC2170.0[m]DC2190.0[m]DC2210.0[m]DC2230.0[m]DC2250.0[m]DC2270.0[m]DC2290.0[m]DC2310.0[m]DC2330.0[m]DC2340.0[m]DC2346.0[m]SWC2350.0[m]DC2355.0[m]SWC2362.5[m]SWC2364.5[m]SWC2380.0[m]SWC2395.0[m]SWC2405.0[m]SWC2418.0[m]SWC2423.0[m]SWC2450.0[m]SWC2483.0[m]SWC2530.0[m]SWC