34/10-7
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General information
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Wellbore history
GeneralWell 34/10-7 was drilled on the eastern segment of the Gullfaks Field. The primary objective was to test sandstones of Middle Jurassic age. Secondary objective was sandstones of Early Jurassic age: the Cook and the Statfjord Formations.Operations and resultsAppraisal well 34/10 7 was spudded with the semi-submersible installation Ross Rig on 7 January 1980 and drilled to TD at 2550 m in the Late Triassic Lunde Formation. Two major problems were encountered during drilling. The first one concerned water sensitive clays which caused difficulties when underreaming the hole for both the 16" liner and the 13 3/8" casing. The second problem was the leak off test below the 9 5/8" casing shoe. While circulating prior the second leak off test the formation broke down. Four cement squeezes were required before a proper formation test was obtained. The well was drilled with spud mud down to 845 m and with gel/lignosulphonate mud from 845 m to TD.Weak to good oil shows were recorded from 1320 m in the lower Hordaland Group and downwards, mostly in limestone. Strong shows with live oil in the mud were recorded between 1380 and 1415 m. Oil shows of variable strength continued all the way down through the Hordaland, Rogaland and Shetland Groups. The Shetland Group was found resting directly on the Early Jurassic Cook Formation sandstone at 1810 m. Oil was found in sandstones of the Cook and Statfjord Formations. No oil/water contact was observed in the Cook Formation. In the Statfjord Formation an oil water contact was found at 2066 m.A total 53.2 m core (67% recovery) was recovered in 5 cores in the interval from 1813 m to 1892 m. A sixth core was taken with 100% recovery from 1942 to 1949 m. RFT fluid samples were taken at 1821 m in the Cook Formation and at 2055 m in the Statfjord Formation.The well was suspended on 23 March 1980 as an oil appraisal well.TestingOne drill stem test was performed from perforation at 1858 - 1856 m in the Cook Formation. The test produced 471 Sm3 oil and 59200 Sm3 gas /day through a 40/64" choke. The GOR was 126 Sm3/Sm3, the oil density was 0.832 g/cm3, and the gas gravity was 0.68 (air = 1) with 0.5% CO2. The maximum temperature at perforation depth was 77.7 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]294.002248.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11813.01819.0[m ]21821.01839.0[m ]31839.01853.7[m ]41857.01865.0[m ]51875.01882.2[m ]61942.01949.6[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]61.5Cores 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 availableDST1833.001840.00YESDSTDST 11558.001865.0017.03.1980 - 15:00YESDSTTEST21835.001865.00OIL01.07.1983 - 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 typeCONDUCTOR30291.036292.00.00LOTSURF.COND.20823.026845.01.51LOTLINER161346.019 1/21415.01.77LOTINTERM.13 3/81565.0181572.01.90LOTINTERM.9 5/81692.012 1/41700.02.02LOTLINER71977.08 1/21990.02.05LOTOPEN HOLE2250.062250.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01833184015.9Drill 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]1.04710.832126 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BGT8321572CBL CCL GR12991565CBL VDL CCL GR11001976CCL12431926COMPUTED RØ RHGX PHIX16992248CYBERDIP16922249DLL MSFL GR16921989FDC CNL GR CAL16852249FDC GR CAL8321571HDT16922249ISF SON GR SP2282248LS SON18001920SON18001920 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit229895934965101510631100113011801308151515151568166616661750181018101937194520532053214021802180 -
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]pdf1.39pdf23.47pdf0.44pdf0.44pdf34.36pdf0.31pdf2.83pdf0.69pdf2.75pdf0.89pdf0.05pdf0.63pdf0.30pdf0.45pdf1.96pdf3.16pdf4.49pdf0.22pdf0.65pdf2.51pdf4.07pdf1.42pdf4.52 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured01.0656.0WATER BASED2041.04120.0WATER BASED3501.0656.0WATER BASED6951.0965.0WATER BASED8231.0852.0WATER BASED11461.1151.0WATER BASED12921.1245.0WATER BASED13901.3575.0WATER BASED15471.6880.0WATER BASED16751.7564.0WATER BASED17881.8553.0WATER BASED -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit1818.90[m ]1818.00[m ]1822.80[m ]1823.10[m ]1825.70[m ]1828.70[m ]1834.70[m ]1838.70[m ]1877.40[m ]1849.10[m ]1815.00[m ]1823.00[m ]1826.00[m ]1833.00[m ]1836.00[m ]1845.00[m ]1879.00[m ]