34/7-4
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General information
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Wellbore history
GeneralWell 34/7-4 was drilled on the Snorre E structure in the northern part of block 34/7. The primary objectives were to further appraise the reservoir potential of the Statfjord Formation in the E-structure extension of the Snorre Discovery, to test the oil/water contact found in wells 34/7-1, and to test the reservoir quality in this area. A secondary objective was to test the reservoir potential in the upper Lunde Formation, which contain oil in an up-dip location.Operations and resultsAppraisal well 34/7-4 was spudded with the semi-submersible installation Treasure Saga on 19 November 1984 and drilled to TD at 3115 m in the Late Triassic Lunde Formation. No significant problems occurred during drilling of the well. The well was drilled with spud mud down to 963 m, with gypsum/polymer mud from 963 m to 2759 m, and with lignosulphonate mud from 2759 m to TD.Except for the sandy Utsira Formation (Late Miocene/Pliocene) and an Early Eocene sandstone unit (1625-1664 m) in the lower part of the Hordaland Group, the well proved mainly claystones down to the Early Jurassic Statfjord Formation at 2535.5 m. The Statfjord Formation was 92 m thick and was oil bearing down to claystones in top Lunde Formation at 2627.5 m. No definite oil-water contact was seen. The N/G ratio in the Statfjord Formation was 0.26. The average porosity was 20 % and the average water saturation was 44%. The Lunde Formation proved mainly a claystone/siltstone sequence in the upper part, while the lowermost 265 m proved a sequence of alternating sandstones and claystones with limestone stringers. Of this sequence some 123 m can be considered as net. The Lunde Formation reservoir was water bearing.Three cores totalling 24.6 m (recovered 22.3 m. 91% recovery) were cut in the Statfjord Formation from 2533 m to 2557.5 m. Core depths were from 2.0 to 4.0 m short of logger's depth. Another two cores were attempted at 2558.5 m and 2559 m, but these gave no recovery. Two FMT-chambers containing reservoir fluid were collected in the Statfjord Formation at 2537 m and 2555 m. These samples proved not to be representative, since the bubble point pressures were too low.The well was permanently abandoned on 16 January 1985 as an oil appraisal.TestingOne drill stem test was carried out in the interval 2547.0 - 2563.0 m in the Statfjord Formation. The zone produced clean oil at a rate of 865 Sm3 /day through a 9.5 mm choke with a wellhead pressure of 130 bar. The reservoir pressure was 386.5 bar and the temperature 91deg C at 2555.0 m. The formation permeability was estimated to 1330 mD and no heterogeneities were observed during the test.The separator GOR was 34 Sm3/Sm3 and the dead oil density was 0.843 g/cc with a Formation Volume Factor of 1.27.> -
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]490.003116.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12533.02536.7[m ]22537.52552.5[m ]32552.52557.6[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]23.8Cores 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 availableDST2563.002547.00YESDSTDST10.000.00YES -
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 typeCONDUCTOR30469.036473.00.00LOTSURF.COND.20953.026971.01.51LOTINTERM.13 3/81015.017 1/21930.01.78LOTINTERM.13 3/81915.017 1/21930.01.90LOTINTERM.13 3/81915.017 1/21930.01.78LOTINTERM.9 5/82745.012 1/42756.01.90LOTINTERM.9 5/82745.012 1/42756.00.00LOTOPEN HOLE3115.08 1/23115.00.00LOTOPEN HOLE3115.08 1/23115.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0254725639.5Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.0192.000131.000385.000Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.0865350000.8330.74033 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CALIPER9531229CDL CN GR19152755CDL CN GR27443073COREGUN00COREGUN00DIELECTRIC24502748DIFL LSBHC9531930DIFL LSBHC GR469970DIFL LSBHC GR19152758DIFL LSBHC GR27443118DIPLOG19152750DIPLOG27443117DLL MLL GR24502757FMT19152750FMT27443117GR120473SPECTRALOG19152750SPECTRALOG27443068VSP3183118 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit345111811871625167516851685171218481848199824962496250425172517253626282628 -
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]pdf1.78pdf37.52 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4081.03100.0WATER BASED21.11.19844731.03100.0WATER BASED21.11.19847021.1062.057.0WATER BASED23.11.19849711.1556.049.0WATER BASED26.11.19849711.2256.056.0WATER BASED26.11.19849711.2259.056.0WATER BASED26.11.19849711.2253.050.0WATER BASED27.11.19849711.2252.048.0WATER BASED27.11.19849711.0754.016.0WATER BASED30.11.19849711.0754.016.0WATER BASED03.12.19849711.2256.056.0WATER BASED26.11.19849711.2259.056.0WATER BASED26.11.19849711.2253.050.0WATER BASED27.11.19849711.2252.048.0WATER BASED27.11.19849711.0754.016.0WATER BASED30.11.19849711.0754.016.0WATER BASED03.12.198411171.1448.018.0WATER BASED11.12.198415521.2748.018.0WATER BASED11.12.198416521.3248.018.0WATER BASED11.12.198419031.3748.018.0WATER BASED12.12.198419301.4426.019.0WATER BASED13.12.198419301.4422.020.0WATER BASED17.12.198419301.4422.020.0WATER BASED17.12.198420721.4433.017.0WATER BASED17.12.198422861.5622.015.0WATER BASED17.12.198423811.6024.018.0WATER BASED18.12.198424981.6950.018.0WATER BASED20.12.198425371.6950.016.0WATER BASED20.12.198425591.6947.013.0WATER BASED27.12.198425591.6949.014.0WATER BASED27.12.198425591.6949.014.0WATER BASED27.12.198425831.6951.015.0WATER BASED06.01.198526301.6948.014.0WATER BASED27.12.198426881.6949.015.0WATER BASED27.12.198427491.6950.016.0WATER BASED27.12.198428101.6050.018.0WATER BASED01.01.198529971.6050.018.0WATER BASED01.01.198531151.6048.013.0WATER BASED06.01.198531151.6049.018.0WATER BASED01.01.198531151.6048.013.0WATER BASED06.01.1985 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1190.0[m]DCRRI1210.0[m]DCRRI1220.0[m]DCRRI1240.0[m]DCRRI1260.0[m]DCRRI1270.0[m]DCRRI1280.0[m]DCRRI1290.0[m]DCRRI1310.0[m]DCRRI1330.0[m]DCRRI1850.0[m]DCRRI1865.0[m]DCRRI1880.0[m]DCRRI1895.0[m]DCRRI1910.0[m]DCRRI