25/11-16
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General information
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Wellbore history
GeneralWell 25/11-16 was drilled south of the Balder Field complex on the Utsira High in the North Sea. The main objective was to test the hydrocarbon potential of the Heimdal Formation within the "Hanna" mound. Possible younger sand developments in the Lista and Sele Formations were secondary targets.Operations and resultsWildcat well 25/11-16 was spudded with the semi-submersible installation Vildcat Explorer on 29 June 1992 and drilled to TD at 1945 m in the Late Cretaceous Hod Formation. The well was drilled with spud mud down to 1339 m and with CaCO3/Nacl mud from 1339 m to TD.The primary target Heimdal Formation was encountered from 1767 m to 1872 m. Gross thickness is 105.75 m with 83.9 m net sand. The formation was oil bearing with 18.87 m net pay of heavy oil (0.85 g/cc at reservoir conditions) down to a series of claystone beds at 1786 m. The average porosity in the oil zone was 37.5% and the average Sw was 12.8%. The reservoir sand is very poorly consolidated, homogenous and has a net to gross ratio in the oil zone of 0.96. The average range of both horizontal and vertical permeabilities is 10 to 14 Darcies. A free water contact was established at 1793 m from MDT data. The oil/water contact appears to occur at the base of the sand unit at ca 1790 m (1765 m TVD MSL). In addition to oil shows in the Heimdal Formation oil zone oil two isolated shows were recorded in thin sand stringers at 1713 m in the Balder Formation and at 1735 m in the Sele Formation.A total of 200 m core was recovered from 14 cores taken in the interval 1699 m to 1914 m (93% recovery), starting 1 m below the top of the Balder Formation and ending 17 m into the Tor Formation. A total of 26 pressure points were recorded with the MDT tool. Fluid samples were taken at 1774 m, 1793.5 m, and 1838 m.The well was suspended without testing on 24 July 1992 as an oil discovery.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]1340.001945.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11699.01713.0[m ]21713.01725.7[m ]31730.01740.3[m ]41747.51748.0[m ]51748.51767.0[m ]61767.51784.0[m ]71784.51786.0[m ]81786.01803.0[m ]91803.01820.7[m ]101821.01838.4[m ]111839.01854.0[m ]121855.01881.3[m ]131882.01886.0[m ]141887.01914.5[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]198.9Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1365.0[m]DCCGG1395.0[m]DCCGG1430.0[m]DCCGG1450.0[m]DCCGG1490.0[m]DCCGG1510.0[m]DCCGG1520.0[m]DCCGG1530.0[m]DCCGG1565.0[m]DCCGG1590.0[m]DCCGG1620.0[m]DCCGG1650.0[m]DCCGG1685.0[m]DCCGG1697.0[m]DCCGG1712.0[m]CCGG1715.5[m]CCGG1722.1[m]CCGG1731.7[m]CCGG1733.4[m]CCGG1733.7[m]CCGG1738.1[m]CCGG1749.9[m]CCGG1752.7[m]CCGG1760.9[m]CCGG1774.2[m]CCGG1788.5[m]CCGG1792.4[m]CCGG1798.0[m]CCGG1810.1[m]CCGG1817.3[m]CCGG1836.1[m]CCGG1856.6[m]CCGG1861.1[m]CCGG1872.2[m]CCGG1874.4[m]CCGG1876.9[m]CCGG1880.9[m]CCGG1884.9[m]CCGG1890.0[m]CCGG -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit145663764836836953152115621698169817331739176718721885189718971936 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf2.84 -
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]pdf17.29 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CST GR13551939DIL DSI LDL CNL NGT SP AMS13351926DLL MSFL GR AMS13361934FMI GR13351615FMI GR15801940MDT GR AMS15241871MWD - GR RES DIR1451945VSP5901930 -
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 typeCONDUCTOR30232.036233.00.00LOTINTERM.9 5/81333.012 1/41335.01.70LOTLINER71764.08 1/21945.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2321.06WATER BASED3401.06WATER BASED11451.06WATER BASED16991.282.5WATER BASED17301.2825.0WATER BASED17671.2824.0WATER BASED18031.2820.0WATER BASED18551.2821.0WATER BASED18551.2821.0WATER BASED19141.2819.0WATER BASED19451.2819.0WATER BASED -
Pressure plots
Pressure plots The pore pressure data is sourced from well logs if no other source is specified. In some wells where pore pressure logs do not exist, information from Drill stem tests and kicks have been used. The data has been reported to the NPD, and further processed and quality controlled by IHS Markit.Pressure plots Document nameDocument formatDocument size [MB]pdf0.19