34/7-7
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General information
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Wellbore history
GeneralWell 34/7-7 was drilled on the western side of the “Inner Main Fault” near the geographic centre of the Snorre Field. The objectives were to test the reservoir quality of the Statfjord Group and the Oil-Water Contact, expected to be at 2611 m. Further objectives were to test the subdivision and reservoir characteristics of the Triassic Lunde Formation.Operations and resultsWildcat well 34/7-7 was spudded with the semi-submersible installation Treasure Saga on 17 September 1985 and drilled to TD at 3526 m in the Late Triassic Lunde Formation. A 17 1/2” pilot hole was drilled from 455 m to 995 m to check for shallow gas before opening up to 26”. No shallow gas was seen. Some fishing jobs were required during logging and testing, otherwise operations proceeded without significant problems. The well was drilled with spud mud down to 455 m, with gel mud from 455 m to 995 m, with gypsum/polymer mud from 995 m to 2562 m, and with gel mud from 2562 m to TD.Well 34/7-7 penetrated top reservoir at 2561.1 m. The OWC was defined at 2615 m in the Statfjord Group. The average log porosity in the oil zone is 26.2%, the net/gross is 0.37, and the average water saturation is 26.2%. Weak oil shows were seen from around 2140 m in sandstone and siltstone from early Campanian in the Shetland Group (top Kyrre Formation) and down to to the top Dunlin Group at 2455 m. Through the Dunlin Group down to the top Statfjord reservoir at 2561 m, the shows became stronger. Below the OWC, a sandstone interval at the bottom of the Statfjord (2640 - 2644 m) had good oil shows. Going into the Upper Lunde, the shows disappear.Nineteen cores were cut and recovered during drilling of the well. Core 1 to 8 were cut from 2563 to 2669.5 m through the whole Statfjord Group and the first meters of the Upper Lunde Formation. Core 9 to 19 were cut in the interval 2888.2 to 3336.7 m in the Upper Lunde Formation. Total core recovery was 197.25 m (94.1%). The core - log depth shifts for the individual cores varied from -0.6 m to +1.8 m. FMT oil samples were taken at 2613.5 m and 2564.8 m.The well was permanently abandoned on 16 December as an oil appraisal well.TestingTwo Drill Stem Tests (DST) were carried out in the Statfjord Group, Eiriksson Formation.DST 1 tested the interval 2561.5-2569.5 m at the top of the oil zone. The test produced 1720 Sm3 oil /day through a 14.3 mm choke. At stock tank conditions the GOR was 68 Sm3/Sm3, the oil density was 0.8362 g/cm3, and the gas gravity was 1.059 (air = 1). The bottom hole temperature was 93 °C.DST 2 tested the interval 2611.7-2614.7 m just above the OWC. The test produced 980 Sm3 oil /day through a 71.8 mm choke. At stock tank conditions the GOR was 62.5 Sm3/Sm3, the oil density was 0.8403 g/cm3, and the gas gravity was 1.081 (air = 1). The bottom hole temperature was 93 °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]460.003526.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12562.02568.0[m ]22569.02574.8[m ]32585.02593.5[m ]42593.52613.0[m ]52614.02623.3[m ]62624.02635.3[m ]72635.52655.0[m ]82656.02667.7[m ]92877.02886.4[m ]102886.42895.7[m ]112895.72905.0[m ]122905.02913.5[m ]132913.72923.1[m ]142923.12932.3[m ]152932.42941.6[m ]162941.62950.8[m ]172951.12963.8[m ]183320.03328.5[m ]193329.03337.5[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]194.7Cores 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 availableDSTDST12561.502569.50OIL13.11.1985 - 15:00YESDSTDST1,10.000.00OIL23.11.1985 - 00:00YESDSTTEST22611.002614.00OIL08.12.1985 - 00:00YES -
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 typeCONDUCTOR30450.036455.00.00LOTSURF.COND.20969.026995.01.50LOTINTERM.13 3/81862.017 1/21878.01.90LOTINTERM.9 5/82750.012 1/42765.01.85LOTOPEN HOLE3526.08 1/23526.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.02562257014.32.02615261217.5Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.02.036.00026.00026.000Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.01720447200.840262.01001394000.84039 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CDL CNL GR18592762CDL GR4501875DIFL LS BHC GR4503524DIP18592759DLL MLL GR24502762FMT25622743FMT27973426MWD4493522SP24502762VSP10003920 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit3299681068114711471678167816931793183718372139244524452455245525602560262926782678 -
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]pdf3.90pdf19.56 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4551.03WATER BASED23.09.19858551.6823.010.1WATER BASED16.12.19858961.118.043.0WATER BASED23.09.19859951.116.046.0WATER BASED23.09.198510001.1052.019.0WATER BASED26.09.198514481.2552.020.0WATER BASED30.09.198518581.4250.021.0WATER BASED30.09.198518781.4250.020.0WATER BASED30.09.198518781.4548.019.0WATER BASED01.10.198518781.5317.010.1WATER BASED07.10.198518781.4518.019.0WATER BASED02.10.198520221.5322.08.2WATER BASED07.10.198523451.6826.08.7WATER BASED07.10.198524751.6830.09.6WATER BASED07.10.198525601.6820.07.7WATER BASED18.11.198525601.6823.06.3WATER BASED18.11.198525611.6823.09.6WATER BASED18.11.198525611.6823.09.6WATER BASED20.11.198525611.6821.09.1WATER BASED25.11.198525611.6825.010.6WATER BASED25.11.198525621.6821.07.2WATER BASED07.10.198525621.6823.06.8WATER BASED07.10.198525621.6824.08.2WATER BASED07.10.198525641.6020.05.8WATER BASED21.10.198525641.6824.05.8WATER BASED21.10.198526111.6824.06.3WATER BASED08.10.198526121.6823.010.1WATER BASED09.12.198526201.6824.06.3WATER BASED11.10.198526401.6822.06.8WATER BASED11.10.198526861.6825.07.2WATER BASED03.11.198526861.6823.011.1WATER BASED19.11.198526861.6820.09.1WATER BASED28.11.198526861.6819.07.7WATER BASED01.12.198526861.6823.010.1WATER BASED09.12.198526861.6822.09.6WATER BASED09.12.198526861.6822.09.6WATER BASED16.12.198526861.6820.07.7WATER BASED18.11.198526861.6823.010.6WATER BASED19.11.198526861.6820.08.7WATER BASED27.11.198526861.6818.07.2WATER BASED28.11.198526861.6818.07.7WATER BASED28.11.198526861.6821.08.2WATER BASED01.12.198526861.6819.07.2WATER BASED01.12.198526861.6820.07.7WATER BASED01.12.198526861.6821.08.7WATER BASED04.12.198526861.6818.09.6WATER BASED09.12.198526861.6825.07.7WATER BASED04.11.198526861.6825.07.7WATER BASED05.11.198526861.6826.08.7WATER BASED08.11.198526861.6826.08.7WATER BASED11.11.198526861.6825.08.2WATER BASED11.11.198526861.6823.07.7WATER BASED13.11.198526861.6824.07.7WATER BASED13.11.198526861.6820.08.2WATER BASED18.11.198527501.6020.04.8WATER BASED31.10.198527501.6018.05.8WATER BASED21.10.198527651.6824.05.8WATER BASED16.10.198527651.6824.05.8WATER BASED16.10.198529051.6019.05.8WATER BASED24.10.198529321.6015.05.3WATER BASED24.10.198529601.6016.05.8WATER BASED24.10.198529881.6017.06.8WATER BASED24.10.198531331.6016.05.3WATER BASED24.10.198532801.6017.06.8WATER BASED28.10.198533361.6017.06.3WATER BASED28.10.198533381.6016.05.8WATER BASED28.10.198535261.6017.05.3WATER BASED31.10.198535261.6020.05.3WATER BASED31.10.198535261.6019.05.3WATER BASED31.10.1985 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory2443.0[m]SWCR.R.I2457.0[m]SWCR.R.I2515.0[m]SWCR.R.I