7120/7-3
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General information
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Wellbore history
GeneralWildcat well 7120/7-3 is located on the Ringvassøy-Loppa Fault Complex west of the Hammerfest Basin and the Snøhvit Field. The primary objective of the well was to test possible hydrocarbon accumulations in sandstones of Middle to Lower Jurassic age.Operations and resultsThe well was spudded with the semi-submersible rig West Vanguard on 18 March 1984 and drilled to TD at 3062 m in the Early Jurassic Nordmela Formation. The well was drilled with seawater and bentonite down to 331 m, with lignosulfonate/gypsum/polymer mud from 331 m to 715 m, with gypsum/polymer mud from 715 m to 1720 m, with polymer mud from 1720 m to 2625 m, and with lignite/polymer mud from 2625 m to TD. The 36" hole had to be reamed before setting of the 30" casing. During cementing of 20" casing returns were lost. Technical problems occurred when testing the BOP stack before drilling out of the 20" casing shoe, and after the 13 3/8" casing job. Mud problems occurred when drilling out of the 20" casing shoe due to cement contamination. Because of tilted wellhead two attempts to run in the casing was needed. When running in an 8 1/2" bit to perform leak off test below the 9 5/8" casing shoe, problems occurred getting the bit through wearbushing in wellhead. After this 4 kg junk was recovered from the hole.The well penetrated Tertiary, Cretaceous, and Jurassic sediments. Lithology down to 2759 m (Base Cretaceous) was dominantly claystone with stringers of sandstone/siltstone/Limestone/Dolomite. The Late Jurassic Hekkingen Formation from 2759 m to 2889 m consisted of shale with stringers of siltstone and limestone and traces of sand. Pyrite was seen in trace amounts in the upper part and was abundant in the lower part of the sequence. From 2889 m to TD, in the Middle to Early Jurassic, the lithology was sandstone with shale interbeds. Trace to faint shows were recorded in claystone cuttings below 1200 m. Good shows, probably residual oil, was recorded on core 2 in the top 1.5 m of the Middle Jurassic Stø Sandstone. Poor to fair shows were seen in sandstones on the cores below this depth down to 2909 m and occasionally on cuttings below 2909 to TD.Geochemical analyses showed that the sediments are marginally mature already at 1350 m, and have reached peak oil maturity from 2750 m down to TD. The Late Jurassic interval from 2759 m to 2863 m is the best source rock in the well with potential for gas and light oil. The claystones above the Jurassic contain sequences with fair to medium source potential, particularly in the Late - Middle Barremian from ca 2170 m to 2580 m has a total organic content in the range 2% - 4% throughout. However, Hydrogen Index was found to be quite moderate throughout the well, not exceeding 150 mg/g in any source sequence.Three cores were cut in the interval from 2867 m to 2910 m in the Middle to Late Jurassic Jurassic. A segregated RFT sample was taken at 2889.5 m. It recovered only water. The well was permanently abandoned as dry with shows on 9 June 1984.TestingNo drill stem test was performed -
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]332.003058.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12867.02884.4[m ]22885.02898.5[m ]32899.02909.5[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]41.4Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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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 typeCONDUCTOR30331.536331.50.00LOTSURF.COND.20700.026715.01.56LOTINTERM.13 3/81700.017 1/21720.01.79LOTINTERM.9 5/82605.012 1/42625.01.59LOTOPEN HOLE3062.08 1/23062.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL CST 9 5/8'00CBL VDL GR 13 3/8'00CBL VDL GR 20'00HDT GR7001412ISF SON GR281715ISF SON GR7001718ISF SON GR16982621ISF SON MSFL GR26053059LDT CNL GR331715LDT CNL GR16982621LDT CNL NGT26053060LDT GR7001719MWD3352735RFT28872998SHDT GR16982623SHDT GR26053059VSP6503050 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit28138038013121312149614962570267927592863288928892969 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.51 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf2.11 -
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]pdf26.91 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured3651.058.024.0WATER BASED4501.06WATER BASED5501.08WATER BASED7251.108.04.0WATER BASED9501.1416.015.0WATER BASED10251.1512.017.0WATER BASED12301.2117.016.0WATER BASED16001.2016.019.0WATER BASED17301.3015.08.0WATER BASED19301.4813.011.0WATER BASED21451.3012.016.0WATER BASED22251.4013.017.0WATER BASED26351.2017.013.0WATER BASED28151.2518.016.0WATER BASED28551.3521.018.0WATER BASED29101.3821.014.0WATER BASED