25/2-21
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General information
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Wellbore history
GeneralWell 25/2-21 is the replacement well for 25/2-20, which was junked due to stuck pipe. It was drilled to test the shallow Liatårnet Prospect in the Fensal Sub-basin east of the Frigg Field in the North Sea. The primary objective was to prove hydrocarbons in the Early Miocene Skade Formation (“Liatårnet sand”).Operations and resultsWildcat well 25/2-21 was spudded with the semi-submersible installation Deepsea Stavanger on 1 July 2019 and drilled to TD at 1200 m in the Late Oligocene sediments in the Hordaland Group. Operations proceeded without significant problems. The well was drilled with seawater and hi-vis pills down to 987 m and with KCl water-based mud from 987 m to TD.Massive Utsira Formation sands were penetrated from at 280 m to 1012.5 m. An 11-meter thick claystone sequence capped the main Liatårnet sand, which was encountered at 1023.5 m. The Liatårnet sand was 28 m vertically thick and hydrocarbon bearing. The entire reservoir was cored and logged. Formation pressure tests in the sands gave a gradient range between 0.8 – 0.9 g/cc. The shallowest oil show in the well is described in thin sandstones at 1018 m, in thin sandstone stringers within the cap rock claystone over the Liatårnet sands. Strong oil shows with fluorescence, cut, stain and bleeding oil were seen throughout the Liatårnet oil-bearing sand to its base at 1052 m.There were no shows below 1052 m. No fluid contacts could be established. A deeper sand penetrated from 1098 to 1010 m was water-bearing with a clear water gradient.Three cores were cut. Core 1 was cut from 1024.8 to 1042.4 m with 96.3% recovery. Cores 2 and 3 were cut from 1042.7 to 1060.8 m with 100% recovery. Despite several attempts to take an MDT fluid sample, only one bottle was filled during sampling in run 1E at 1025.5 m. Schlumberger Saturn probe was used during this sampling. One 420 cc MPSR bottle were filled after major troubles with sand infill in lines and pump. MPSR bottle was sent to Stratum Reservoir laboratories for analysis. After major challenges in opening the MPSR bottle, pressure was bled of and content was proved to be a slurry of sand and oil. In addition, a small quantity of oil was drained from the cores on the rig. Onshore analyses proved a biodegraded, heavy oil.The well was permanently abandoned on 15 July 2019 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]991.001200.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11025.81041.8[m ]21042.71046.4[m ]31046.41060.8[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]34.0Cores 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 typeCONDUCTOR36203.042206.40.00SURF.COND.9 5/8984.012 1/4987.01.36FITOPEN HOLE1024.88 1/21024.80.00 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]FMI PPC MSIP HRLA PEX HNGS GR9211200FTNG10351035IBC CBL153986LWD - DI140206LWD - GR RES PWD SON206986LWD - RES PWD GR NEU DEN SON9861200MDT10251107XPT NEXT MRX GR10031172 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit141280101310241052 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured3001.03Water3001.10Water9871.20Water10421.20Water12001.20Water12001.21Water -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory991.0[m]CPETROSTR1003.0[m]CPETROS1012.0[m]CPETROS1024.0[m]CPETROS1025.6[m]CPETROS1028.9[m]CPETROS1030.9[m]CPETROS1046.5[m]CPETROS1049.8[m]CPETROS1050.6[m]CPETROS1052.6[m]CPETROS1053.9[m]CPETROS1057.1[m]CPETROS1059.8[m]CPETROS1069.0[m]CPETROS1087.0[m]CPETROS1105.0[m]CPETROS1123.0[m]CPETROS1144.0[m]CPETROS1168.0[m]CPETROS1195.0[m]CPETROS1200.4[m]CPETROS