25/10-12 S
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General information
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Wellbore history
GeneralWell 25/10-12 S was drilled to test the Kopervik Prospect on the west flank of the Utsira High, close to the Hanz Field in the North Sea. The primary objective was to test the hydrocarbon potential of Late Jurassic Intra-Draupne Formation sandstone. Secondary objective was sandstones in the Early-Middle Jurassic sequence (Statfjord-Sleipner-Hugin units)Operations and resultsWildcat well 25/10-12 S was spudded with the semi-submersible installation Island Innovator on 27 October 2014. The well was drilled to a total depth of 1800 m in Early Eocene sediments in the Hordaland Group. While running the 9 5/8" casing, the string became differentially stuck at 1520 m. The well was plugged back to the 20" casing shoe and technically sidetracked as 25/10-12 ST2. The latter was drilled to final TD at 2597 m (2570 m TVD) in the Smith Bank Formation. Only MWD logs are available from the well. Wireline logging was attempted at TD of the 8 1/2" hole, however, due to problems below the 9 5/8" casing shoe, no logging was possible. The well was drilled with seawater and high viscosity pills down to 558 and with Aquadril mud from 558 m to TD.Top Draupne Formation was penetrated at 2114 m (2087.3 m TVD). The Draupne Formation in the well consists of mudstones and interbedded thin beds of spiculitic sandstones. At 2124 m (2097.3 m TVD), the base of Draupne, there is a 1.7 m thick Intra-Draupne Formation sandstone. The well also penetrated 21 m and 19.5 m of high quality sand belonging to the Hugin and Sleipner Formations respectively, and approximately 198 m of Statfjord Group sediments with several well-developed sandy intervals. Some weak oil-shows were described in the Intra Draupne sandstones and in the Hugin-Sleipner sandstones, but no stain or cut were observed. The LWD pressure measurements showed a complex depletion history with five different pressure regimes implying several sealing intervals. The pressure points in the Triassic were hydrostatic.Four conventional cores were cut in the sidetrack. Cores 1 and 2 were cut from 2113 to 2136 m with 79 % total recovery. The core-log depth shift was 1.2 m for both cores. Cores 3 and 4 were cut from 2157 to 2201 m with 93 % total recovery. The core-log depth shift was 0.0 m for both cores. Formation pressures were acquired using a Baker TesTrak LWD tool No fluid sample was taken.The well was permanently abandoned on 18 January 2015 as a dry 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]560.001800.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12113.02129.7[m ]22132.02133.6[m ]32157.02181.9[m ]42182.82198.9[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]59.3Cores 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 typeCONDUCTOR30213.336218.00.00SURF.COND.20551.026558.01.69LOTPILOT HOLE558.09 7/8558.00.00INTERM.13 3/81428.117 1/21436.01.86LOTLINER9 5/82068.012 1/42076.01.81LOTOPEN HOLE2597.08 1/22597.00.00 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]MDT20722072MDT20742074MWD - ATK3 OTKII SDTK CCN ORD ZT13702076MWD - ATK3 OTKIISDTK ZTK BCPM NB495585MWD - OTK BCPM APX137556MWD - OTK BCPM2 LTK SD ZTKG20222597MWD - OTK BCPM2 ZTKG TTK23152485MWD - OTKII NBG BRES APX4941436XPT20782078XPT20802080XPT CALI20802080XPT CHAIN20782078 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit146146709790857857862101211221410154915971612188518851934194219862042207820812081208621072107211421142126215321532174219421942241224122492324243924392540 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1901.4012.0Water Based3001.031.0Water Based4251.2516.0Water Based5581.0430.0Water Based6481.1817.0Water Based9051.3519.0Water Based12671.1814.0Water Based13501.4029.0Water Based13511.1813.0Water Based14161.4024.0Water Based14361.1815.0Water Based15501.4023.0Water Based20321.3017.0Water Based22011.1611.0Water Based25971.149.0Water Based25971.2210.0Water Based