16/4-5
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General information
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Wellbore history
GeneralWell 16/4-5 was drilled on the Luno High prospect located south of the Luno field on the southern Utsira High in the North Sea. The general objectives were to refine the resource potential of the Greater Luno Area and to increase the regional understanding of the sedimentary sequences and fractured basement facies across the Utsira High. The specific objective was to prove the presence of oil bearing sandstones in the Late Jurassic to Early Cretaceous sequence or in conglomerates in the Triassic to Middle Jurassic sequence. The well would test the Luno regional oil-water contact at 1940 m MSL or the alternative oil-water contact established in well 16/1-12, 1928 m MSL. In case of a discovery test production rates in the variable reservoir facies by means of one or more DSTs would be conducted. Planned depth was 2300 m RKBOperations and resultsWildcat well 16/4-5 was spudded with the semi-submersible installation Transocean Winner on 2 February 2010 and drilled to TD at 2020 m in pre-Devonian basement rock. This was 280 m shallower than planned because the prognosed reservoir conglomerates or fractured basement were not encountered. At TD in the 12 1/4" section at 1790 m large quantities of mechanical and stress-release cavings, thought to originate from the Lista and Sele Formations, were circulated out of the hole. Otherwise the were no mud losses or other hole problems in the well. A very slow ROP of approximately 2.5 m/hr was obtained in the 8 1/2" hole below the core point with an insert bit. This was due to the hard, granitic formation. The well was drilled with seawater and hi-vis pills down to 600 m and with Glydril KCl mud from 600 m to TD.No Cretaceous or Late Jurassic age sandstones or Middle Jurassic to Triassic age conglomerates were encountered in the well. Well 16/4-5 proved oil shows in faulted/fractured granitic basement underlying red coloured marls of Hauterivian to Valanginian age. The granitic basement was highly fractured, as seen from the FMI log; however, analysis of the core showed that a large majority of these fractures were tightly cemented. Several fractures were open and contained traces of migrated hydrocarbons, mainly characterised by black tarry material, dry and flaky in some cases.Two cores were cut in the interval 1896 m to 1925.7 m across BCU and into basement. A number of attempts to measure formation pressures and take fluid samples were made using a Schlumberger MDT tool, however, the formation proved too tight. No pressure results were obtained. One MDT fluid sample recovered from 2002.5 m was found to contain drilling fluid only; otherwise no fluid samples were taken.The well was permanently abandoned on 7 March as a well with shows.TestingThe fractured granitic basement did not have reservoir characteristics, therefore the well was not production tested. -
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]610.002020.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11896.01898.7[m ]21898.01924.8[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]29.5Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
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 typeCONDUCTOR30207.036207.00.00LOTSURF.COND.13 3/8594.017 1/2600.01.70LOTPILOT HOLE606.09 7/8606.00.00LOTINTERM.9 5/81785.012 1/41790.01.50LOTOPEN HOLE2020.08 1/22020.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]FMI PPC MSIP17652026FMI PPC MSIP CBL VDL8931777HRLT PEX ECS HNGS17642021MDT GR18762002MWD LWD - GR RES PWD DIR125605MWD LWD - GR RES PWD DIR17851892MWD LWD - GR RES PWD DIR DEN NEU5951785MWD LWD - GR RES PWD DIR DEN NEU17852016VSI7052000 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit130752912991991120416771677168917191777178017801812187618951898 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.39 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]txt0.00txt0.25 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2091.50Water2091.05Water6001.30Water14401.35Water16171.20Water17901.38Water18981.20Water20201.20Water