31/6-5
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General information
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Wellbore history
GeneralWell 31/6-5 was drilled in the southern part of the Troll East gas province, 30 m from well 31/6-4, which was junked for technical reasons. The main purpose was to appraise and test possible oil and gas accumulations in sandstones of Late to Middle Jurassic age, and to give further information about lateral facies changes within the reservoir sandstones.Operations and resultsAppraisal well 31/6-5 was spudded with the semi-submersible installation Deepsea Bergen on 5 March 1984 and drilled to TD at 2082 m in the Early Jurassic Drake Formation. In the 26" hole lost circulation occurred at 653 m, two cement plugs were set. Several wiper trips were taken due to tight hole. After setting of the 20" casing, the BOP had to be repaired due to leaking during pressure testing. A drilling break occurred at 1476 m in the 12 1/4" hole. The well was drilled with the spud mud from the previous hole (31/6-4) treated with CMC-EHV down to 389 m, with seawater/gel mud from 389 m to 663 m, with KCl/polymer mud from 663 m to 1720 m, and with seawater/gel/CMC mud from 1720 m to TD.Sandstone of Late to Middle Jurassic age (Sognefjord Formation) was encountered at 1518 m with a 52 m gas column and a 4 m oil column. The gas/oil contact was at 1570 m and the oil/water contact at 1574 m. Oil shows were recorded on sidewall cores on top Fensfjord Formation sandstone from 1722 m to 1726 m and on a sandstone SWC from 2010 m in the Ness Formation. Ten cores were cut from 1470 m to 1721 m in the Late to Middle Jurassic sequence (Heather Formation to Fensfjord Formation). One FMT fluid sample was taken in the oil zone 1571.5 m. Geochemical analyses showed the oil to be biodegraded.The well was permanently abandoned on 16 March 1984 as a gas and oil appraisal.TestingThe Sognefjord Formation was tested through gravel pack from the interval 1558 m to 1568 m. The first test gave a non-representative flow due to obstructions in the hole. The second test, termed Test 1A, was ok and produced gas at a maximum rate of 1266000 Sm3/day on a 1.5" choke. Geochemical analyses showed the gas to be 92.4% methane and biodegraded. -
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]410.002081.50 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11470.01497.3[m ]21497.01518.0[m ]31523.01550.5[m ]41550.51557.4[m ]51557.51584.0[m ]61584.01611.0[m ]71611.01637.8[m ]81638.01665.8[m ]91665.51693.5[m ]101693.01720.7[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]246.2Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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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 availableDSTTEST1A1568.001558.0015.05.1984 - 11:30YES -
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 typeCONDUCTOR30389.236390.50.00LOTSURF.COND.20649.026656.01.54LOTINTERM.13 3/81424.017 1/21445.01.76LOTINTERM.9 5/81706.912 1/41721.01.62LOTOPEN HOLE2082.08 1/22082.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01558156838.1Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.01266000 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]4-ARM DIP STRATADIP14242081ACBL3231424CALIPER14931534CDL CNL GR CAL14242079CDL GR CAL6491445COLLARLOG14001600DIFL BHC AC GR SP CAL3892082DLL MLL GR14242079DLWD401504FMT14901602PHOTONLOG14881580SPECTRALOG14242076VDL11501705VELOCITY10002080 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit3274558168169601080114411441157125612561312134713881388148015181677170219371972199920352035 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.33 -
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]pdf28.81pdf1.31pdf6.37pdf0.81pdf0.30pdf17.51pdf3.73pdf0.60pdf1.43pdf5.61pdf0.25pdf9.77pdf10.32pdf2.28pdf1.19pdf0.88pdf15.53pdf16.88pdf6.44 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4301.0540.0WATER BASED5501.0739.0WATER BASED6601.1054.0WATER BASED7601.2247.0WATER BASED10651.2348.0WATER BASED11551.2247.0WATER BASED12601.2649.0WATER BASED15801.2252.0WATER BASED17251.1059.0WATER BASED -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory690.0[m]SWCSTATO752.0[m]SWCSTATO790.0[m]SWCSTATO850.0[m]SWCSTATO890.0[m]SWCSTATO930.0[m]SWCSTATO1010.0[m]SWCSTATO1050.0[m]SWCSTATO1110.0[m]SWCSTATO1130.0[m]SWCSTATO1310.0[m]SWCSTATO1380.0[m]SWCSTATO1395.0[m]SWCSTATO1400.0[m]SWCSTATO1410.0[m]SWCSTATO1415.0[m]SWCSTATO1425.0[m]SWCSTATO1430.0[m]SWCSTATO1440.0[m]SWCSTATO1442.0[m]SWCSTATO1446.0[m]SWCSTATO1452.0[m]SWCSTATO1456.0[m]SWCSTATO1460.0[m]SWCSTATO1468.0[m]SWCSTATO1473.7[m]SWCSTATO1518.0[m]SWCSTATO1520.0[m]SWCSTATO1786.0[m]SWCSTATO1821.0[m]SWCSTATO1880.0[m]SWCSTATO1993.0[m]SWCSTATO1998.0[m]SWCSTATO2036.0[m]SWCSTATO2046.0[m]SWCSTATO2080.0[m]SWCSTATO -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit1492.55[m ]1525.35[m ]1536.50[m ]1556.50[m ]1562.35[m ]1573.15[m ]1587.10[m ]1591.40[m ]1601.75[m ]1610.50[m ]1627.50[m ]1637.90[m ]1646.73[m ]1660.00[m ]1664.00[m ]16.00[m ]1677.50[m ]1686.70[m ]1698.00[m ]1491.00[m ]1493.00[m ]1514.00[m ]1517.00[m ]1591.00[m ]1525.00[m ]1573.00[m ]1537.00[m ]1541.00[m ]1547.00[m ]1557.00[m ]1562.00[m ]1580.00[m ]1587.00[m ]1602.00[m ]1611.00[m ]1622.00[m ]1628.00[m ]1638.00[m ]1647.00[m ]1653.00[m ]1711.00[m ]