25/7-1 S
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General information
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Wellbore history
GeneralWell 25/7-1 S was drilled in the southern part of the Viking Graben, close to the UK border. The primary objective was test Late Jurassic sands in a down thrown fault block located northwest of the Balder Field. Secondary objectives were Middle Jurassic sandstones and the Paleocene Heimdal Formation sands, if developed. Prognosed TD was 4525 m.Operations and resultsWildcat well 25/7 1S was spudded with the semi-submersible installation Nortrym on 14 April 1986 and drilled to TD at 3592 m in Silurian basement. While tripping from 1525 m the pipe became stuck and this resulted in a 38 m fish being left in the hole from 1067 to 1105 m. The kick off to bypass the fish was at 1024 m. The hole was then drilled to 2094 m before becoming stuck at 1930 m during a trip. The drill string was freed again after 5 days. Drilling then proceeded to 2477 m at which depth the pipe became stuck for a further 17 hours. The well was drilled with seawater down to 1024 and with KCl/polymer mud from 1024 m to TD. Two % diesel was added to the mud below 3241 m to alleviate high torque.The original geological model for the prospect was wrong. Jurassic - Devonian rocks were not found. A possible explanation is that drilling took place along a fault zone. No good hydrocarbon indications or fluorescence were observed in the well. One sample at 2084 m (Balder Formation) was described as having an orange/brown medium fluorescence, occasionally bright, with a fast, strong, cream/white fluorescent cut.One core was cut at 3547.0 - 3554.8 m across an indeterminate, possibly Triassic section overlying basement, and a second at 3589.0 - 3592.0 m in basement rock. No wire line fluid samples were taken.The well was permanently abandoned on 19 July 1986 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]260.003590.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13589.03591.5[m ]23547.03554.8[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]10.4Cores 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 typeLaboratory1901.0[m]DCRRI1919.0[m]DCRRI1940.0[m]DCRRI1961.0[m]DCRRI1979.0[m]DCRRI2000.0[m]DCRRI2009.0[m]DCRRI2024.0[m]DCRRI2069.0[m]DCRRI2081.0[m]DCRRI2090.0[m]DCRRI2111.0[m]DCRRI2120.0[m]DCRRI2141.0[m]DCRRI2159.0[m]DCRRI2411.0[m]DCRRI2447.0[m]DCRRI -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit15250792510171992199220662177241425722572261528593217352235223551 -
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]pdf2.68pdf13.83 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]HRT CCL602300ISF LSL MSFL GR32852401ISF SLS GR SP32723349ISF SLS GR SP34503592ISF SLS MSFL GR2522200LDL CNL GR10102201LDL CNL GR25232808LDL CNL GR32723592SHDT GR32723592VELOCITY10003575WST VSP10003575 -
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 typeCONDUCTOR30252.036252.00.00LOTINTERM.201009.0261024.00.00LOTINTERM.13 3/82396.017 1/22409.00.00LOTINTERM.9 5/83273.012 1/43286.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2521.0460.02681.0WATER BASED16.04.19867271.13WATER BASED18.04.198610241.10WATER BASED21.04.198611081.2020.025.0WATER BASED02.05.198611511.0810.020.0WATER BASED25.04.198615251.2018.023.0WATER BASED28.04.198617251.2824.029.0WATERBASED06.05.198619341.3024.029.0WATERBASED06.05.198620941.3224.020.0WATERBASED12.05.198620940.0032.022.0WATERBASED13.05.198621671.3234.027.0WATER BASED19.05.198622331.3237.023.0WATER BASED19.05.198623781.3238.026.0WATER BASED19.05.198624091.3140.036.0WATERBASED23.05.198624091.3338.020.0WATERBASED05.06.198624681.3238.030.0WATERBASED05.06.198632061.4030.025.0WATERBASED15.06.198632201.5041.015.0WATERBASED16.06.198632411.5640.015.0WATERBASED17.06.198632851.6847.016.8WATERBASED19.06.198632861.7347.014.4WATERBASED22.06.198633831.9038.012.4WATERBASED29.06.198634211.9038.010.5WATERBASED29.06.198634761.9238.010.5WATERBASED02.07.198635921.9228.08.6WATERBASED13.07.198635920.0028.08.6WATERBASED13.07.198635920.0025.07.2WATERBASED16.07.198635920.0019.04.3WATERBASED17.07.198635920.00WATERBASED19.07.1986