15/12-6 S
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General information
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Wellbore history
Block 15/12 is situated between the Jรฆren High to the south, Central Graben to the south-southwest, Andrew Ridge to the west, Ling Graben to the north and Viking Graben to the north-northwest. Well 15/12-6 S was the third well within the license area. It was drilled ca 3 km north of the 15/12-4 Varg Discovery well, which found 1.5 oil column in Jurassic sandstone. The main objective of 15/12-6 S was to test the hydrocarbon potential in Oxfordian sandstone in the north-western segment of the Beta west structure. Secondary objectives were Palaeocene sandstones (Maureen formation) and Triassic sandstones. Due to possible shallow gas problems, the well was moved 100 south to avoid this problem.Operations and resultsWell 15/12-6 S was spudded 19 August 1990 with the semi-submersible rig Deepsea Bergen and drilled to 3050 m in the Triassic Skagerrak Formation. While drilling the 12 1/4" hole the penetration stopped at 2560 m. The BHA was pulled out and it was found that the MWD tool had been twisted off. The hole was cemented back and sidetracked from 2495 m with increased mud weight. Ran 7" liner to 3046 m, and cemented inside the liner to 2960 m. No shallow gas was encountered. The well was drilled with bentonite spud mud and CMC/seawater down to 615 m, with gypsum/polymer mud from 615 m to 2757 m, and with gel/lignosulphonate mud from 2757 m to TD.Logs and shows indicated presence of hydrocarbons in the interval from 2428 to 2473 m in the late Cretaceous chalk but tests were not performed here due to tight formation. The Late Jurassic Oxfordian sandstone (Hugin Formation) came in at 2871 m, 80.5 m deeper than prognosed. It contained oil and from logs the OWC was found to be at 2943 m. There were no shows or other hydrocarbon indications below this depth.A total of seven cores were cut, six in the interval 2838 to 2966 m and the seventh from 2980 to 2988.5 m. An FMT run in Oxfordian sandstone gave 12 pressure readings out of 27 attempts. One sample was taken at 2935.5 m. The sample contained a mixture of mud filtrate and formation water with traces of hydrocarbons.The well was suspended on 4 November 1990 as an oil appraisal well, and was converted to development well (15/12-A-2).TestingTwo DST tests were performed in this well:DST 1 from 2922 - 2930 m produced 153.8 Sm3/d oil and 11.683 Sm3/d gas through a 12.7 mm choke. The GOR was 76 Sm3/Sm3. A breakthrough, possibly through a fault, occurred at the end of the cleanup flow in this test, and this totally changed well productivity and also altered the flowing temperature. Before the breakthrough the temperature was 127 deg C and still increasing. After breakthrough the temperature sunk to 123 deg C.DST 2 from 2875 - 2895 m produced 866 Sm3/d oil and 52530 Sm3/d gas through a 15.9 mm choke. The GOR was 61 Sm3/Sm3, the oil density was 0.843 g/cm3 and the gas gravity was 0.740 (air = 1). The reservoir temperature was measured to 127.5 deg 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]620.002787.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12838.02864.6[m ]22865.02891.8[m ]32892.02907.9[m ]42910.02937.4[m ]52937.62953.0[m ]62953.02964.4[m ]72980.02988.3[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]131.8Cores 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 typeLaboratory1250.0[m]DCGEOCH1270.0[m]DCGEOCH1280.0[m]DCGEOCH1300.0[m]DCGEOCH1310.0[m]DCGEOCH1330.0[m]DCGEOCH1340.0[m]DCGEOCH1360.0[m]DCGEOCH1370.0[m]DCGEOCH1390.0[m]DCGEOCH1400.0[m]DCGEOCH1420.0[m]DCGEOCH1430.0[m]DCGEOCH1450.0[m]DCGEOCH1460.0[m]DCGEOCH1480.0[m]DCGEOCH1490.0[m]DCGEOCH1510.0[m]DCGEOCH1520.0[m]DCGEOCH1540.0[m]DCGEOCH1550.0[m]DCGEOCH1570.0[m]DCGEOCH1580.0[m]DCGEOCH1600.0[m]DCGEOCH1610.0[m]DCGEOCH1630.0[m]DCGEOCH1640.0[m]DCGEOCH1660.0[m]DCGEOCH1670.0[m]DCGEOCH1690.0[m]DCGEOCH1700.0[m]DCGEOCH1715.0[m]DCGEOCH1730.0[m]DCGEOCH1750.0[m]DCGEOCH1760.0[m]DCGEOCH1780.0[m]DCGEOCH1790.0[m]DCGEOCH1810.0[m]DCGEOCH1820.0[m]DCGEOCH1840.0[m]DCGEOCH1850.0[m]DCGEOCH1870.0[m]DCGEOCH1880.0[m]DCGEOCH1900.0[m]DCGEOCH1910.0[m]DCGEOCH1930.0[m]DCGEOCH1940.0[m]DCGEOCH1951.0[m]SWCSTATOIL1960.0[m]DCGEOCHEM1970.0[m]DCGEOCHE1990.0[m]DCGEOCHE2000.0[m]DCGEOCHE2020.0[m]DCGEOCHE2030.0[m]DCGEOCHE2050.0[m]DCGEOCHE2060.0[m]DCGEOCHE2080.0[m]DCGEOCHE2110.0[m]DCGEOCHE2120.0[m]DCGEOCHE2140.0[m]DCGEOCHE2150.0[m]DCGEOCHE2170.0[m]DCGEOCHE2180.0[m]DCGEOCHE2200.0[m]DCGEOCHE2210.0[m]DCGEOCHE2230.0[m]DCGEOCHE2240.0[m]DCGEOCHE2260.0[m]DCGEOCHE2270.0[m]DCGEOCHE2290.0[m]DCGEOCHE2300.0[m]DCGEOCHE2306.0[m]DCGEOCHE2310.0[m]SWCSTATOIL2318.0[m]DCGEOCHEM2324.0[m]DCGEOCHE2342.0[m]DCGEOCHE2360.0[m]DCGEOCHE2372.0[m]DCGEOCHE2384.0[m]DCGEOCHE2402.0[m]DCGEOCHE2417.0[m]DCGEOCHE2417.0[m]SWCSTATOIL2426.0[m]DCGEOCHEM2432.0[m]DCGEOCHE2736.0[m]SWCSTATOIL2747.5[m]SWCSTATOI2755.0[m]SWCSTATOI2761.3[m]SWCSTATOI2768.5[m]SWCSTATOI2780.5[m]SWCSTATOI2787.5[m]SWCSTATOI2791.5[m]SWCSTATOI2803.5[m]SWCSTATOI2810.9[m]SWCSTATOI2821.9[m]SWCSTATOI2835.5[m]SWCSTATOI2839.2[m]CSTATOI2840.5[m]C2840.6[m]C2845.2[m]CSTATOIL2845.2[m]CSTATOI2849.5[m]C2850.5[m]CSTATOIL2856.5[m]CSTATOI2861.7[m]CSTATOI2866.3[m]CSTATOI2868.5[m]C2868.6[m]CSTATOIL2869.5[m]C2871.4[m]CSTATOIL2871.5[m]C2887.3[m]CSTATOIL2896.4[m]CSTATOI2899.1[m]C2900.8[m]CSTATOIL2901.5[m]CSTATOI2912.5[m]C2913.5[m]C2913.6[m]CSTATOIL2926.3[m]CSTATOI2929.5[m]CSTATOI2936.5[m]C2936.7[m]CSTATOIL2942.7[m]CSTATOI2943.7[m]CSTATOI2947.4[m]CSTATOI2947.4[m]C2950.2[m]CSTATOIL2951.0[m]CSTATOI2951.8[m]CSTATOI2953.9[m]CSTATOI2957.2[m]CSTATOI2960.0[m]CSTATOI2986.2[m]CSTATOI3047.0[m]SWCSTATOI -
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 availableDSTTEST12922.002930.0013.10.1990 - 20:00YESDSTTEST22875.002895.0024.10.1990 - 19:30YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit10710201252231123112323235124212428242825482708273227462746283428712871294929792979 -
Geochemical information
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Documents โ reported by the production licence (period for duty of secrecy expired)
Documents โ reported by the production licence (period for duty of secrecy expired) Document nameDocument formatDocument size [MB]pdf2.12pdf13.79 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.02922293012.72.02875289515.9Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[ยฐC]1.010.0001232.08.000127Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.0154116830.8500.795762.0866525300.8430.74061 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]ACBL VDL GR951701ACBL VDL GR14502926CDL CNL GR CAL23452756DIFL AC SP GR27423048DIFL ACL SP GR16992756DIPLOG GR24012755DIPLOG GR27433049FMT GR24292470FMT HP GR29763032MLL DLL GR27423019MWD - GR RES DIR1703090SP27423049VELOCITY5003050ZDL CN SL27423049 -
Casing and leakโoff tests
Casing and leakโoff tests Casing typeCasing diam.
[inch]Casing depth
[m]Hole diam.
[inch]Hole depth
[m]LOT/FIT mud eqv.
[g/cm3]Formation test typeCONDUCTOR30167.036167.00.00LOTINTERM.20599.026615.01.56LOTINTERM.13 3/81700.017 1/21715.01.82LOTINTERM.9 5/82743.012 1/42757.01.97LOTLINER73046.08 1/23050.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured6150.00WATER BASED23.08.19906151.03DUMMY27.08.19906181.1515.05.0WATER BASED27.08.199013551.1521.05.5WATER BASED27.08.199017101.3021.05.5WATER BASED28.08.199017101.3023.06.5WATER BASED29.08.199017101.3023.06.0WATER BASED30.08.199017101.3022.06.0WATER BASED31.08.199018511.4020.06.0WATER BASED04.09.199021551.4020.06.0WATER BASED04.09.199022001.5022.06.5WATER BASED04.09.199023101.5023.06.0WATER BASED04.09.199023101.5023.06.0WATER BASED05.09.199023101.5023.06.5WATER BASED06.09.199023101.5523.06.5WATER BASED07.09.199023101.5523.07.0WATER BASED10.09.199023101.5022.06.5WATER BASED04.09.199023101.5523.06.0WATER BASED10.09.199023101.5823.08.0WATER BASED14.09.199023101.6125.010.0WATER BASED17.09.199023101.6126.09.5WATER BASED17.09.199023101.6124.010.0WATER BASED18.09.199023101.6125.010.0WATER BASED17.09.199023101.5523.06.0WATER BASED10.09.199023101.5523.07.0WATER BASED13.09.199023451.5023.06.0WATER BASED04.09.199024741.5022.06.5WATER BASED04.09.199024951.5523.06.5WATER BASED07.09.199025111.5523.07.0WATER BASED10.09.199025201.5523.06.0WATER BASED10.09.199025601.5023.06.5WATER BASED06.09.199025601.5023.06.0WATER BASED05.09.199025871.5523.06.0WATER BASED10.09.199027431.3215.04.0WATER BASED25.09.199027431.3228.04.0WATER BASED05.10.199027431.3230.05.0WATER BASED08.10.199027431.3228.05.0WATER BASED08.10.199027431.3228.04.5WATER BASED08.10.199027431.3224.05.0WATER BASED26.09.199027431.3222.05.0WATER BASED27.09.199027431.3224.04.0WATER BASED01.10.199027431.3228.05.0WATER BASED01.10.199027431.3223.05.0WATER BASED26.09.199027431.3228.04.0WATER BASED01.10.199027431.3221.04.0WATER BASED01.10.199027431.3221.04.0WATER BASED02.10.199027431.3226.04.0WATER BASED03.10.199027431.3228.04.0WATER BASED04.10.199027571.6126.09.5WATER BASED17.09.199027571.6124.010.0WATER BASED18.09.199027571.6125.010.0WATER BASED17.09.199027571.6125.010.0WATER BASED20.09.199027571.6125.010.0WATER BASED20.09.199027571.6126.010.0WATER BASED21.09.199027571.6126.010.0WATER BASED24.09.199027571.6126.010.0WATER BASED25.09.199027571.5523.07.0WATER BASED13.09.199027571.6125.010.0WATER BASED17.09.199027571.5823.08.0WATER BASED14.09.199028301.3215.04.0WATER BASED25.09.199028651.3223.05.0WATER BASED26.09.199028761.3228.04.0WATER BASED05.10.199028761.3228.05.0WATER BASED08.10.199028761.3230.05.0WATER BASED08.10.199028761.3228.04.5WATER BASED08.10.199029101.3224.05.0WATER BASED26.09.199029521.3222.05.0WATER BASED27.09.199029661.3224.04.0WATER BASED01.10.199029851.3228.04.0WATER BASED01.10.199029851.3228.05.0WATER BASED01.10.199029851.3221.04.0WATER BASED02.10.199029851.3221.04.0WATER BASED01.10.199030191.3226.04.0WATER BASED03.10.199030501.3228.04.0WATER BASED04.10.199030501.3230.05.0WATER BASED08.10.199030501.3228.04.0WATER BASED05.10.199030501.3228.05.0WATER BASED08.10.199030501.3228.04.5WATER BASED08.10.1990 -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit2892.20[m ]2892.80[m ] -
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