16/1-31 S
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General information
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Wellbore history
GeneralWell 16/1-31 S was drilled to test the Jorvik prospect on the Utsira High, about 4 kilometres northeast of the Edvard Grieg platform in the North Sea. The primary objective was to prove oil in conglomerates from the Triassic Age in an extension of the Edvard Grieg basin toward the east.Operations and resultsAppraisal well 16/1-31 S was spudded with the semi-submersible installation Leiv Eiriksson on 10 March 2019 and drilled to TD at 2220 m in conglomerates of indeterminate Triassic to Permian age. Operations proceeded without significant problems. The well was drilled with seawater and hi-vis pills down to 602 m and with Polymer water-based mud from 602 m to TD.The well penetrated the Early Cretaceous Åsgard Formation directly overlying top of the target reservoir at 1938 m (1866.4 m TVD). The reservoir contained an oil column of about 30 metres in conglomerates and conglomeratic sandstones, presumably of Triassic Age and with generally poor reservoir quality. There was around one metre of sandstone of good quality in the upper part of the reservoir section. The oil/water contact was not proven. Pressure measurements showed that the area is in communication with the Edvard Grieg field. The reservoir pressure was depleted 9-10 bar compared to the Edvard Grieg before start of production.Below 1968 m and down to 2028 m shows are described on cores as: faint to moderate odour, 40% patchy weak, dark yellow direct fluorescence, slow blooming good bluish white cut fluorescence, 30% moderately, cream fluorescent residue. Patchy shows (cut and fluorescence) was described on sidewall cores down to 2176.5 m.Three cores were cut in the interval 1940 to 2034.5 m. Recoveries were 100%, 97.7%, and 99.3% in cores 1, 2 and 3 respectively. MDT fluid samples were taken at 1938.61 m (oil) and 1964.57 m (oil).The well was plugged back for side-tracking (16/1-31 A) on 10 May 2019. The well was initially classified as a wildcat but has been reclassified as an oil appraisal well.TestingA drill stem test was conducted from perforations in the interval 1945.15 to 2001.9 m. The test produced oil and gas at relatively low rates, between 21 to 24 Sm3 oil and 4900 to 8000 Sm3 gas /day through a 26/64” choke. The GOR was between 233 and 333 Sm3/Sm3, but this was likely not representative due to slugging. The temperature at gauge depth 1920.9 m was 80.2°C. -
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]610.002220.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11940.01967.2[m ]21967.22004.1[m ]32005.02034.3[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]93.4Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Oil samples at the Norwegian Offshore Directorate
Oil samples at the Norwegian Offshore Directorate Test typeBottle numberTop depth
MD [m]Bottom depth
MD [m]Fluid typeTest timeSamples availableMDT0.000.00YESMDT1939.570.00OIL17.04.2019 - 00:00NOMDT1913.600.00OIL16.04.2019 - 00:00NO -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit13613677787193094511941510160416491750175017611793187418991899191119231929192919311938 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0194520029.52.0194520029.5Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.09.4002.08.400Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.02149002332.0248000333 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]FMI MSIP GR1001912FMI MSIP GR15002221HRLA PEX HNGS GR19102221MDT GR19382080MWD - GR PWD RES DIR AC179599MWD - INC GR RES PWD CAL DEN N A13352220MWD - PWD DIR221590MWD - PWD GR147192MWD - RES PWD GR DIR AC5951334XLR GR13761600XLR GR14001905XLR GR19182199XPT NEXT CMR19102221 -
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 typeCONDUCTOR30203.136203.10.00SURF.COND.20595.026602.01.50FITPILOT HOLE602.09 7/8602.00.00INTERM.13 3/81337.617 1/21345.01.88LOTLINER9 5/81910.212 1/41911.01.65LOTLINER72219.68 1/22220.00.00 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2031.051.0PHB Sweep2031.501.0KCl/Polymer/GEM5701.3021.0HP WBM6021.3015.0HP WBM6021.041.0PHB Sweep6021.5017.0KCl/Polymer/GEM6101.3016.0HP WBM10201.3020.0HP WBM13451.3019.0HP WBM13451.4523.0HP WBM13991.4525.0HP WBM19111.1219.0HP WBM19111.4530.0HP WBM19301.1216.0HP WBM20351.1217.0HP WBM20351.1413.0HP WBM20801.1214.0HP WBM22201.3021.0HP WBM22201.131.0KCl Brine22201.1211.0HP WBM