34/8-8
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General information
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Wellbore history
GeneralWell 34/8-8 was drilled to appraise the N-1 segment of the 34/8-1 Visund discovery on Tampen Spur in the Northern North Sea. The N-1 segment is estimated to contain approximately 30% of the resources in the Brent-North area. Confirmation of these resources was critical for reservoir management and production layout in future development plans. The primary objectives of the well were thus to confirm the resources in the Brent Group and to obtain data that could be used in reservoir engineering studies on improved oil recovery. Secondary objectives were evaluations of the Statfjord Formation and the Lunde B/C Formation. The well design and location was chosen primarily to evaluate the Brent target with respect to defining fluid contacts in clean sands, avoid faults, and penetrate as close as possible to the erosion edge of the top of the Brent Group.Operations and resultsAppraisal well 34/8-8 was spudded with the semi-submersible installation Transocean 8 on 30 June 1992 and drilled to TD at 3625 m in the Late Triassic Lund Formation. After drilling to 1430 m in the 12 1/4" section the drill string got stuck. 16.55 m of the BHA was left in the hole and the hole was plugged back to 1354 m where a minor technical sidetrack was performed. After setting the 30" casing an industry strike caused ca 5 days downtime. The well was drilled with spud mud down to 1364 m, and with Anco 2000 glycol mud from 1364 m to TD.The Brent Group was encountered at 2921 to 3077 m. It was oil bearing and wire line logs confirmed an OWC at 2971 m, while RFT pressure tests suggested a free water level between 2973.4 m and 2976.8 m. From a gross Brent Group thickness of 156 m, a net pay thickness of 97 m was identified. An average porosity of 20.6% and average Sw of 34.7% were computed for the Brent Group oil zone. The Cook Formation, from 3122.5 to 3260 m, was found to be water wet without shows. The Amundsen Formation, from 3287 to 3387.5 m, was mainly claystone, but had a 12 m thick sandstone towards its base. The Amundsen Formation was water wet without shows. The Statfjord Formation was penetrated from 3387.5 to 3475 m. From a gross thickness of 87.5 m, a total net sand thickness of 46.25 m was recognised. The Lunde Formation was encountered at 3475 m and continued to TD. Both the Statfjord and Lunde formations were water wet without shows. Apart from in the oil bearing Brent reservoir, oil shows were recorded only in cuttings from thin sand stringers at 2460 m, 2515 m, and 2615 m in the Kyrre Formation.Ten conventional cores were cut in the well. The whole of the Brent Group was cored in eight cores and two cores were taken in the Hegre Group. RFT fluid samples were taken at 2923.3 m in the Brent oil zone (water and filtrate), 2940 m in the Brent oil zone, at 2983.5 m in the Brent water zone (water and some gas), at 3390 m in the top of the Statfjord Formation (water and some gas).The well was suspended on 24 August 1992 with the provision for further testing. It is classified as an oil appraisal.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]1370.003620.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12885.02912.0[m ]22912.02919.0[m ]32920.52948.0[m ]42948.02975.8[m ]52976.53004.0[m ]63004.03031.5[m ]73031.53066.0[m ]83068.53083.0[m ]93503.03517.2[m ]103567.43575.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]215.1Cores 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 typeLaboratory2880.0[m]DCGEOSTR2887.0[m]DCGEOSTR3258.0[m]SWCHYDRO3367.0[m]SWCHYDRO3440.0[m]SWCHYDRO3477.0[m]SWCHYDRO3482.0[m]SWCHYDRO3565.0[m]SWCHYDRO -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit36411151164119013681401152715591829182918731998199822322877287728832901290129022921292129352967300830773077312332603287338834743474 -
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]pdf22.13 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CST GR28303596CST GR30933596DIL LSS GR SP CAL AMS3602735DIL LSS LDL CNL NGL SP AMS27643622DLL MSFL LDL CNL GR SP AMS27643294FMI GR27643622MWD - GR RES DIR3643625NMRT28623105NMRT28653110RFT GR29223256RFT HP GR29222964RFT HP GR29833505RFT HP GR33903390SUMT GR GHMT28603105VELOCITY14103600 -
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 typeCONDUCTOR30451.036452.00.00LOTINTERM.13 3/81351.017 1/21353.01.66LOTINTERM.9 5/82765.012 1/42766.01.82LOTLINER73170.08 1/23625.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4321.0314.0WATER BASED4521.0614.0WATER BASED6211.2024.0WATER BASED9001.2023.0WATER BASED11121.0513.0WATER BASED13481.3914.0WATER BASED13601.3924.0WATER BASED13641.3914.0WATER BASED13901.3812.0WATER BASED13921.3920.0WATER BASED14301.3919.0WATER BASED15121.4026.0WATER BASED17671.3925.0WATER BASED21791.4729.0WATER BASED24591.4728.0WATER BASED27651.4730.0WATER BASED28851.6229.0WATER BASED29161.6230.0WATER BASED29481.6233.0WATER BASED29901.6528.0WATER BASED30061.6037.0WATER BASED30321.6229.0WATER BASED30741.6233.0WATER BASED31091.6730.0WATER BASED31141.6232.0WATER BASED31721.7030.0WATER BASED33001.6233.0WATER BASED34751.6031.0WATER BASED35161.6034.0WATER BASED36251.6034.0WATER 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]pdf0.22