34/10-8
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General information
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Wellbore history
GeneralWell 34/10-8 was drilled on the southern part of the Gullfaks Field. The primary objective was to test sandstones of Middle Jurassic age. Secondary objectives were sandstones in the Early Jurassic.Operations and resultsAppraisal well 34/10-8 was spudded with the semi-submersible installation Deepsea Saga on 8 March and drilled to TD at 2214 m in the Early Jurassic Cook Formation. Some problems with lost circulation was encountered when circulating prior to cementing the 13 3/8" casing. Also the drill string became stuck during plug back operations at 2037 m and 9 days were lost when fishing for it. The well was drilled with Gel/spud mud down to 875 m and with gel/lignosulphonate from 875 m to TD.The Middle Jurassic Brent Group sandstones came in with Tarbert Formation on top at 1821 m and the Ness Formation at 1853 m. The Tarbert and Ness formations were hydrocarbon-bearing with a 151 m gross pay zone from1821 to 1972 m. The Early Jurassic sandstones of the Cook Formation were water saturated. Above the reservoir good oil shows were recorded on limestone from 1712 to 1745 m and on limestone/mudstone/siltstone from 1665 to 1705 m. Otherwise traces of oil shows were recorded above the reservoir up to a depth of 1220 m. No shows were recorded below the oil bearing reservoir.A total of 13 cores were taken from 1823 to 1976 m, with a total recovery of 140 m. The RFT tool was run in the Brent sand and good data was obtained from 1826 to 2006 m. Fifteen out of seventeen tests were successful. In the Ness zone a fluid sample was taken at 1950 m.The well was permanently abandoned on 25 May 1980 as an oil appraisal well.TestingThe well was perforated and tested in the interval 1869 to 1873 m in the Brent Group, Ness Formation. The test produced 498 Sm3 oil and 33900 Sm3 gas /day. The GOR was 68 Sm3/Sm3, the oil gravity was 29.5 deg API, and the gas gravity was 0.622 (air = 1). After the flow test an injection test was performed, indicating a fracture pressure of ca 5500 psig. -
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]230.002216.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11823.01828.5[m ]21828.51832.5[m ]31839.01851.5[m ]41856.51860.8[m ]51861.51869.0[m ]61877.01883.6[m ]71885.01898.5[m ]81898.51908.5[m ]91908.51925.0[m ]101925.01939.5[m ]111939.51956.0[m ]121956.01956.6[m ]131964.01975.8[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]123.8Cores 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 availableDSTDST 11845.001848.0017.05.1980 - 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 typeCONDUCTOR30216.036216.00.00LOTSURF.COND.20858.026875.01.63LOTINTERM.13 3/81470.017 1/21483.01.75LOTINTERM.9 5/81735.012 1/41745.01.90LOTLINER71917.08 1/22216.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01845184812.7Drill 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]1.05010.882117 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL6001727CBL VDL15821877CST17482210DLL MSFL GR18002017FDC CAL GR8581483FDC CNL GR14701744HDT17322216ISF SON GR SP2162216 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1589339461096136515341534157517191719182118211853197520052040205420542133 -
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]pdf1.31pdf22.29pdf8.43pdf2.72pdf2.15pdf26.84pdf1.44pdf2.10pdf3.06pdf0.20pdf0.45pdf3.42pdf1.09 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2001.0890.0waterbased7551.0945.0waterbased8251.1039.0waterbased10251.0844.0waterbased13501.2644.0waterbased15501.6546.0waterbased16101.7248.0waterbased17351.8053.0waterbased -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit1840.00[m ]1828.00[m ]1842.00[m ]