35/8-3
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General information
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Wellbore history
GeneralWell 35/8-3 was drilled in the southern end of the Sogn Graben in the Northern North Sea. The primary objective was to assess the hydrocarbon potential of the Brent Group sandstones, which flowed gas-condensate in wells 35/8-1 and 35/8-2. The Brent Group was expected to be 212 m thick and to be encountered at a depth of 3631 m subsea. Secondary objectives were Late Jurassic Intra-Heather Formation sandstones, and possible Intra-Early Cretaceous sandstones.Operations and resultsWildcat well 35/8-3 was spudded with the semi-submersible installation Treasure Scout on 6 July 1988 and drilled to TD at 3944 m (3947 m logger's depth) in the Middle Jurassic Brent Group. No shallow gas was observed. While drilling the 12 1/4" section the drill string got stuck in Heather sands at 3539 m. After 7 days unsuccessful fishing the hole was plugged back to 3308 m. It was sidetracked from 3371 m and drilled to section TD at 3560 m. The BHA got stuck a second time at 3863 m in the 8 1/2" section. After 5 days with several fishing attempts by jarring the BHA was fished after spotting a diesel based fluid. The diesel was circulated out and the well was drilled to its final TD. The well was drilled with spud mud down to 830 m, with Drispac and seawater from 830 m to 2174 m, and with KCl/polymer mud from 2174 m to TD.Hydrocarbon indications while drilling were minor except in the Late Jurassic Heather sands. Log analyses of the Heather sands indicated a probable gross gas column of 70 m with a net pay of 31.9 m. Average porosity in the net sand was 15.6% with an estimated average water saturation of 22%. An RFT pressure-depth plot confirmed a gas column with an estimated 0.162 psi/ft (3.66 KPa/m) pressure gradient. No gas/water contact was apparent. Shows were encountered while drilling the Brent Group sands, but analyses of wire line logs and RFT's indicated the interval was water bearing. No reservoir rocks were encountered in the Early Cretaceous age formations.One conventional core was cut from 3830 to 3848.4 m. Recovery was 100% and consisted of sands and shales of the Ness Formation, Brent Group. Two RFT fluid samples were taken at 3467 m (0.04 Sm2 gas and 10 litres mud filtrate with trace of oil), and at 3859.5 m (10 litres mud filtrate and formation water, no gas or oil).The well was permanently abandoned on 15 October 1988 as a gas 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]840.003944.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13830.03848.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]18.0Cores 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 typeLaboratory2730.0[m]DCRRI2745.0[m]DCRRI2760.0[m]DCRRI2775.0[m]DCRRI2790.0[m]DCRRI2805.0[m]DCRRI2824.0[m]DCRRI2840.0[m]DCRRI2857.0[m]DCRRI2875.0[m]DCRRI2890.0[m]DCRRI2905.0[m]DCRRI2926.0[m]DCRRI2941.0[m]DCRRI2959.0[m]DCRRI2978.0[m]DCRRI3002.0[m]DCRRI3018.0[m]DCRRI3034.0[m]DCRRI3048.0[m]DCRRI3146.0[m]DCRRI3176.0[m]DCRRI3206.0[m]DCRRI3236.0[m]DCRRI3266.0[m]DCRRI3294.0[m]DCRRI -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit3967301468146815301663172017741787179217921960312231273140314032163318331833953465354738103810382038803896 -
Geochemical information
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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]pdf22.26 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CST GR21803557CST GR35753942DIS LSS GR SP21603560DIS LSS GR SP CAL8192141DLL MAFL GR SP33003556DLL MSFL GR SP CAL35453941LDL CNL GR CAL21603561LDL CNL GR CAL35453946LSS GR35453943RFT GR38143946RFT HP GR34413467SHDT35453946VSP5003945 -
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 typeCONDUCTOR30531.036845.00.00LOTSURF.COND.20818.5261022.01.42LOTINTERM.13 3/82159.517 1/22174.01.65LOTINTERM.9 5/83545.512 1/43560.01.84LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4401.3213.04.0WATER BASED12.10.19884401.3211.03.0WATER BASED13.10.19886850.00WATER BASED15.08.19888450.00WATER BASED16.08.198811501.1415.06.2WATER BASED19.08.198812051.1414.06.2WATER BASED19.08.198814741.1414.06.2WATER BASED19.08.198817861.1515.05.7WATER BASED19.08.198818621.1816.05.2WATER BASED19.08.198819741.1815.06.2WATER BASED19.08.198820231.3213.08.0WATER BASED11.10.198820431.3213.08.0WATER BASED10.10.198821481.1814.05.7WATER BASED19.08.198821741.1814.03.8WATER BASED19.08.198821741.1813.03.3WATER BASED19.08.198821741.1814.05.7WATER BASED19.08.198822711.1814.05.7WATER BASED19.08.198823201.1812.04.8WATER BASED19.08.198824741.2010.04.8WATER BASED19.08.198825001.3213.08.0WATER BASED10.10.198825241.2012.04.8WATER BASED19.08.198826971.2512.06.7WATER BASED19.08.198828431.2510.04.8WATER BASED19.08.198828851.2510.04.8WATER BASED22.08.198829741.259.04.8WATER BASED22.08.198829951.2613.07.2WATER BASED22.08.198830621.2613.07.6WATER BASED22.08.198831271.2613.06.2WATER BASED22.08.198831661.2613.07.2WATER BASED22.08.198832161.2711.05.7WATER BASED22.08.198832911.2711.05.2WATER BASED22.08.198832921.2711.04.8WATER BASED22.08.198833001.3213.06.7WATER BASED29.08.198833451.3216.06.2WATER BASED29.08.198833711.3215.07.2WATER BASED30.08.198833771.2911.04.8WATER BASED22.08.198833791.3214.05.7WATER BASED31.08.198833961.3214.05.7WATER BASED02.09.198834021.3214.05.7WATER BASED02.09.198834261.3217.06.2WATER BASED05.09.198834351.0313.06.7WATER BASED22.08.198834501.6120.012.0WATER BASED10.10.198834631.3218.01.6WATER BASED05.09.198834671.3013.05.7WATER BASED22.08.198834921.3112.05.7WATER BASED22.08.198835001.3213.06.2WATER BASED22.08.198835021.3218.07.6WATER BASED05.09.198835391.3214.06.7WATER BASED23.08.198835391.3214.07.2WATER BASED24.08.198835391.3214.07.2WATER BASED25.08.198835391.3217.07.2WATER BASED26.08.198835391.3217.07.2WATER BASED29.08.198835391.3213.07.2WATER BASED22.08.198835601.3217.08.0WATER BASED08.09.198835601.3217.07.5WATER BASED13.09.198835601.3216.07.5WATER BASED06.09.198835601.3217.07.5WATER BASED08.09.198835601.3217.07.5WATER BASED09.09.198835601.3216.07.0WATER BASED13.09.198835631.4816.07.5WATER BASED14.09.198835981.4818.0WATER BASED14.09.198836101.4820.06.0WATER BASED15.09.198836741.6120.07.0WATER BASED16.09.198837321.6124.07.5WATER BASED19.09.198837371.6125.08.0WATER BASED19.09.198837501.6120.06.0WATER BASED07.10.198837631.6127.05.5WATER BASED19.09.198837841.6127.05.0WATER BASED20.09.198838061.6124.05.0WATER BASED21.09.198838331.6124.05.0WATER BASED22.09.198838531.6121.05.0WATER BASED23.09.198839441.6120.05.5WATER BASED26.09.198839441.6120.05.5WATER BASED27.09.198839441.6120.04.0WATER BASED29.09.198839441.6120.04.0WATER BASED30.09.198839441.6120.05.0WATER BASED04.10.198839441.6119.05.0WATER BASED04.10.198839441.6120.06.0WATER BASED05.10.198839441.6123.06.0WATER BASED26.09.198839441.6120.05.5WATER BASED28.09.198839441.6120.06.0WATER BASED06.10.1988 -
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]pdf0.22