31/6-8
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General information
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Wellbore history
GeneralAppraisal well 31/6-8 was drilled in the south-west corner of the Troll East gas province, 50 m due north of well 31/6-7, which was junked and abandoned for technical reasons. The main objectives were to determine the lateral extent of the reservoir, to determine the fluid contacts in the Sognefjord Formation, and to obtain the best possible seismic correlation within the reservoir from well 31/6-1. In addition, an elaborate testing program was planned to obtain a number of reservoir engineering parameters.Operations and resultsWell 31/6-8 was spudded with the semi-submersible installation Treasure Seeker on 14 April 1985 and drilled to TD at Drilling the well proceeded without significant problems. The interval down to setting depth for 20" casing was not logged, as this interval was considered covered by logs from well 31/6-7. The well was drilled with spud mud down to 700 m, with KCl Polymer mud from 700 m to 1465 m, and with "drill in fluid" (NaCl, polymers, and CaCO3) from 1465 m to TD. An 8 m3 Imcospot/Pipelax pill was spotted at 2054 m to free the pipe, which was stuck.The Sognefjord Formation (1507-1661 m) was found gas bearing from 1507 m to 1573.5 m and oil bearing from 1573.5 to 1578.5 m where the oil/water contact was found. The oil zone was determined from petrophysical evaluation, core plug saturations and segregated sample recoveries. The hydrocarbon-bearing reservoir consisted of predominantly very fine to fine grained sandstones with some interbedded siltstones. The gross hydrocarbon column was 71.5 m and the net pay calculated to 67 m with an average porosity of 33% and average water saturation of 16.2 %. No hydrocarbon indications were recorded above 1507 m or below 1579 m.Twelve cores were cut in the Late to Middle Jurassic Sognefjord and Heather Formations from 1489 m to 1700 m (148 m total recovery). FMT segregated samples were taken at 1573.2 m (0.7 Sm3 gas, 0.5 l water/filtrate, and 6 l oil in 2.75 gallon chamber) and at 1578.8 m (0.1 Sm3 gas, 0.5 l oil, and 9.8 l water/filtrate in 2.75 gallon chamber).The well was temporarily suspended 25 may 1985, and subsequently re-entered for testing 20 July 1985.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]420.002137.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom21503.01512.0[m ]31520.01530.0[m ]41537.01551.0[m ]51555.01566.0[m ]61567.51586.0[m ]71586.01604.0[m ]81604.51623.0[m ]91623.01641.0[m ]101641.51659.0[m ]111663.01673.0[m ]121681.51699.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]162.0Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit32553898598511121224125612561264137113711385141214121485150716611705192719651985200820082025 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.30 -
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]pdf29.32pdf3.67pdf0.76pdf2.42 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01538155823.82.0152315230.03.0141614180.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.02.03.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.0260002.03.0 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL CCL GR12001596CET GR12001596CST7501442CST14461659CST16622124DLL MSFL GR CAL14371655HDT11001442ISF LSS GR SP6872140LDL CNL GR CAL6871442LDL CNL NGS GR CAL14372142RFT14871640RFT15591578SHDT14371659SHDT16472142TEMP4001400VELOCITY6872140 -
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 typeCONDUCTOR30411.036416.00.00LOTSURF.COND.20687.026700.01.54LOTINTERM.13 3/81437.017 1/21465.01.59LOTINTERM.9 5/81646.012 1/41660.01.57LOTOPEN HOLE2138.08 1/22138.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4161.35WATER BASED16.04.19857001.0810.020.0WATER BASED17.04.19857001.106.013.0WATER BASED18.04.19857000.00WATER BASED19.04.19857001.2028.018.0WATER BASED21.04.19857001.2018.07.0WATER BASED21.04.19857001.106.013.0WATER BASED18.04.19857001.2028.018.0WATER BASED21.04.19857001.2018.07.0WATER BASED21.04.19857001.2018.07.0WATER BASED23.04.19857001.2018.07.0WATER BASED23.04.19858601.2019.08.0WATER BASED25.04.19859461.16WATER BASED21.08.198510831.2718.05.0WATER BASED26.04.198510831.2718.06.0WATER BASED25.04.198510831.2718.05.0WATER BASED26.04.198511711.2418.09.5WATER BASED29.04.198511851.16WATER BASED21.08.198512211.2416.07.0WATER BASED29.04.198512211.2316.08.0WATER BASED30.04.198512211.2417.08.0WATER BASED29.04.198512211.2416.07.0WATER BASED29.04.198512211.2316.08.0WATER BASED30.04.198513541.2315.011.0WATER BASED02.05.198514651.2518.012.0WATER BASED02.05.198514651.2519.012.0WATER BASED06.05.198514651.2519.011.0WATER BASED06.05.198514651.2622.010.0WATER BASED06.05.198514651.2519.012.0WATER BASED06.05.198514651.2519.011.0WATER BASED06.05.198514651.2622.010.0WATER BASED06.05.198514821.16WATER BASED21.08.198514821.16WATER BASED22.08.198514821.16WATER BASED29.08.198514821.16WATER BASED14.08.198514821.16WATER BASED19.08.198514891.2010.08.0WATER BASED07.05.198515041.2015.010.0WATER BASED08.05.198515121.16WATER BASED05.09.198515121.16WATER BASED06.09.198515121.16WATER BASED09.09.198515371.2025.014.0WATER BASED09.05.198515621.16WATER BASED29.08.198515621.16WATER BASED30.08.198515621.16WATER BASED03.09.198515671.2049.012.0WATER BASED10.05.198515701.1615.014.0WATER BASED11.09.198515800.00WATER BASED23.05.198516051.2013.08.0WATER BASED13.05.198516151.209.05.0WATER BASED26.07.198516151.209.05.0WATER BASED30.07.198516151.03WATER BASED30.07.198516151.03WATER BASED31.07.198516151.16WATER BASED02.08.198516151.16WATER BASED06.08.198516151.209.05.0WATER BASED30.07.198516151.03WATER BASED30.07.198516151.03WATER BASED31.07.198516151.16WATER BASED02.08.198516151.16WATER BASED06.08.198516191.16WATER BASED08.08.198516191.16WATER BASED09.08.198516191.16WATER BASED13.08.198516191.16WATER BASED08.08.198516191.16WATER BASED09.08.198516191.16WATER BASED13.08.198516191.16WATER BASED06.08.198516411.2013.08.0WATER BASED13.05.198516601.2013.08.0WATER BASED13.05.198516601.2011.09.0WATER BASED14.05.198516601.2013.07.0WATER BASED15.05.198516601.2013.08.0WATER BASED21.05.198516601.2013.07.0WATER BASED15.05.198516601.2013.08.0WATER BASED21.05.198516601.2011.09.0WATER BASED14.05.198516631.2013.07.0WATER BASED21.05.198516891.2013.08.0WATER BASED21.05.198518711.2015.010.0WATER BASED21.05.198520591.2015.08.0WATER BASED21.05.198521380.0025.07.198521381.2026.07.198521381.2014.09.0WATER BASED22.05.198521381.2026.07.198521381.2014.09.0WATER BASED21.05.198521381.2014.09.0WATER BASED22.05.1985 -
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]pdf0.20