15/5-2
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General information
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Wellbore history
GeneralWell 15/5-2 was drilled in the Ve Sub-basin in the North Sea, north of the Sleipner Vest Field and 15/5-1 Gina Krog Discovery. The main objective of the well was to test possible hydrocarbon accumulations in Middle to Late Jurassic Bathonian/Callovian transgressive sandstones and Middle Jurassic Bajocian deltaic sandstones. The well was located in a purposely off-crestal position on an approximately 16 km2 large structure some 7 km north-west of the 15/5-1 discovery.The well was planned to penetrate into the Triassic with a projected total depth of 4500 m.Operations and resultsWildcat well 15/5-2 was spudded with the semi-submersible installation Treasure Seeker on 16 August 1978 and drilled to TD at 4322 m in the Triassic Hegre Group. At 1267 m, the string unscrewed in a tight section, but it was fished without problems. After drilling to 2293 m, the string stuck when pulling out of hole. This time the fish was not recovered and a sidetrack was performed with kick-of at 1775 m. Heavy weather caused further delays, otherwise the drilling went forth without significant problems to TD. The well was drilled with seawater mud mixed with gel and Spersene down to 454 m, and with a Spersene/XP-20 (lignosulphonate) mud from 454 m to TD. At 2232 m 1% Diesel was added to the mud.Two hydrocarbon bearing sandstone intervals were penetrated by the well. In the Jurassic, only a thin Early to Middle Bathonian sandstone development was penetrated between 4035 m and 4055 m. Interbeds of siltstones and shales reduced the 20 m gross pay to a net pay of 7.3 m from wireline log interpretation. Average porosity and average water saturation over the pay interval was calculated to 14.3 and 41.7% respectively. The top of the Triassic sandstones was encountered at 4141.3 m and continued with interbeds of varicoloured shales and siltstones to TD. From wireline log evaluation hydrocarbon bearing sandstones were seen down to 4158.1 m. Below this a tight cemented sandstone appears, masking the exact hydrocarbon - water contact. Proven gross pay interval is thus 16.8 m while the net pay is 12.8 m. Average porosity over this interval has been calculated to 14.6 % and the average water saturation to 43 %.Above top Jurassic weak oil shows were observed on limestones at 2792 and 2828 m in the Tor Formation, between 3488 m and 3517 m in the Lower Hod and Blodøks formations, and between 3707 m and 3723 m in the Rødby Formation. In the Jurassic oil shows were recorded on sandstones from 4008 m to 4055 m. In the Triassic, no oil shows were seen despite the hydrocarbon saturation (gas) in the sandstones shown by the logs.Two cores were cut in the Middle Jurassic sequence. Core 1 was taken from 4013.6 m to 4020.6 m and recovered 5.1 m (72.8 %). The core was decided to be cut based on sandstone occurrence in the ditch cuttings, but only shale and coal beds were found in the core. Core 2 was cut from 4032.5 m to 4043.0 m and recovered 9.8 m (93.3 %). The core to log depth shift is ca +4.5 m for both cores. RFT fluid samples were attempted at 4148.5 m, 4145 m, 4053 m, and 4157.5 m. Only mud filtrate was retrieved at all depths.The well was suspended on 16 December 1978 for future re-entry and testing. It is classified 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]195.004323.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom14013.64018.8[m ]24032.54042.3[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]15.0Cores 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 typeLaboratory3765.0[m]DCRRI3820.0[m]DCRRI3850.0[m]DCRRI4034.1[m]CRRI -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit14575891016082128212821622204225226062650270527052782296735073588364736473759375938313960396039954113 -
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]pdf3.12pdf13.18 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CCL03696CPI40054295CST16552990CST30003710CST37203992CST37534288CST37534315CST37584140CST39124147CST39253964CST39684323DLL MSFL40004324FDC CNL4554325HDT15933712HDT36904323HRT5411589HRT26553652ISF SON1924326RFT39904292RFT40530RFT41480RFT41570VELOCITY5004323 -
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 typeCONDUCTOR30194.036194.50.00LOTSURF.COND.20454.026469.00.00LOTINTERM.13 3/81598.017 1/21615.00.00LOTINTERM.9 5/83696.012 1/43714.00.00LOTLINER74300.08 1/24322.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1941.20waterbased4691.14waterbased14621.20waterbased36821.34waterbased38721.43waterbased40131.59waterbased -
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]pdf0.21