7/7-1
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General information
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Wellbore history
GeneralWell 7/7-1 was the first well in license 148, and was designed to drill a tilted block on the Jæren High close to the UK border. Early/Middle Jurassic events resulted in uplift and erosion, such that Jurassic sediments at the well location are missing. Due to the Tertiary uplift and eastward tilting of the Shetland Platform, along with a relative drop in sea level, this tilting gave rise to an eastward drainage pattern. Submarine fan sandstones derived from deltaic and barrier bar complexes in the Morray Firth area were deposited in the Central Graben and on to the Jæren High. Several lobe systems developed, giving rise to continuous and periodic sandstone deposition as the lobes migrated laterally. The eastern pinch out of these systems occurs in blocks 7/4 and 7/7. The primary objective of this well was an anticlinal closure at the Base Cretaceous Unconformity level, the C-prospect, Triassic sandstones. The secondary objective was the B-prospect, Paleocene sandstones, a possible closure along a pinch out of a sandy sequence consisting of distal turbidites. Some high amplitude anomalies indicated shallow gas between 241 to 395 m. The nearest one at 308 m was situated approximately 300 m east of the well location. Sticky and swelling "gumbo" clays are common in the area.Operations and resultsWildcat well 7/7-1 was spudded with the semi-submersible installation Deepsea Bergen 30 December 1989 and drilled to TD at 3500 m in the Triassic Smith Bank Formation. The well was drilled with seawater and gel down to 572 m, with gypsum/polymer mud from 572 m to 3263 m, and with bentonite/lignosulphonate mud from 3263 m to TD. Apart from some tight hole problems, drilling went without severe problems. No shallow gas was encountered. The well was drilled approximately 200 m into the Triassic, which consisted of brick red sandstones, interbedded with siltstone / claystone. The Paleocene sandstones came in nearly 60 m below the prognosed depth, and only minor amounts of sand was encountered (Andrew Formation). No indication of hydrocarbons was seen in this well. Two conventional cores were cut, one from 2786 m to 2803 m in the Paleocene Andrew Formation and a second from 3286 m to 3313.5 m driller's depth (3291.5 m to 3319 m loggers depth) in the Smith Bank Formation. A total of 125 sidewall cores were attempted, and 118 sidewall cores were recovered. No fluid samples were taken. The well was permanently abandoned on 20 February 1990 as a dry hole.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]590.003500.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12786.02803.0[m ]23296.03313.5[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]34.5Cores 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 typeCONDUCTOR30167.036168.00.00LOTINTERM.20567.026580.01.64LOTINTERM.13 3/82548.0182565.01.86LOTINTERM.9 5/83251.012 1/43263.01.63LOTOPEN HOLE3500.08 1/23500.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL GR13332554CBL VDL GR19033253DIFL ACL CDL CNL GR25483260DIFL ACL CDL CNL GR32533502DIFL ACL CDL GR5672567DIPS GR32543499FMT GR32903317MLL SPL32533505MWD5723500SWC GR20212566SWC GR26493258SWC GR32603503VSP1003490 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit106125626262626266027582780280828302830292531083243324332883288 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.57 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf0.23 -
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]pdf18.43 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured5761.03WATER BASED05.01.19905801.03WATER BASED05.01.19905801.03WATER BASED08.01.199025651.5629.06.0WATER BASED16.01.199025651.5626.06.0WATER BASED16.01.199025651.5625.05.0WATER BASED17.01.199025681.5021.05.0WATER BASED24.01.199026851.5022.04.0WATER BASED25.01.199026901.5021.04.5WATER BASED26.01.199027641.5022.06.0WATER BASED29.01.199027861.5021.05.0WATER BASED29.01.199028031.5023.05.0WATER BASED29.01.199029031.5024.06.5WATER BASED30.01.199029971.5027.06.0WATER BASED31.01.199030471.5027.05.5WATER BASED02.02.199030541.5025.04.5WATER BASED05.02.199031141.5025.05.0WATER BASED06.02.199032631.5025.05.5WATER BASED07.02.199032631.5023.05.0WATER BASED07.02.199032631.5027.05.0WATER BASED08.02.199032841.5545.06.0WATER BASED12.02.199032841.5543.06.5WATER BASED14.02.199032841.5542.05.0WATER BASED14.02.199032841.5543.05.5WATER BASED15.02.199032941.5540.012.5WATER BASED20.02.199032941.5540.010.0WATER BASED20.02.199032941.5543.05.5WATER BASED16.02.199032941.5542.010.5WATER BASED20.02.199033651.5543.06.5WATER BASED14.02.1990 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory2022.0[m]SWCSTATO2074.0[m]SWCSTATO2111.0[m]SWCSTATO2122.0[m]SWCSTATO2135.0[m]SWCSTATO2143.2[m]SWCSTATO2175.0[m]SWCSTATO2225.0[m]SWCSTATO2275.0[m]SWCSTATO2310.0[m]SWCSTATO2325.0[m]SWCSTATO2344.0[m]SWCSTATO2360.0[m]SWCSTATO2382.2[m]SWCSTATO2400.0[m]SWCSTATO2415.0[m]SWCSTATO2431.0[m]SWCSTATO2450.0[m]SWCSTATO2464.0[m]SWCSTATO2479.0[m]SWCSTATO2500.0[m]SWCSTATO2513.5[m]SWCSTATO2530.0[m]SWCSTATO2545.0[m]SWCSTATO2560.0[m]SWCSTATO2580.0[m]DCRRI2595.0[m]DCRRI2610.0[m]DCRRI2625.0[m]DCRRI2640.0[m]DCRRI2649.5[m]SWCSTATO2658.5[m]SWCSTATO2679.0[m]DCRRI2694.0[m]DCRRI2706.0[m]SWCSTATO2724.0[m]DCRRI2739.0[m]DCRRI2742.0[m]SWCSTATO2753.0[m]SWCSTATO2758.3[m]SWCSTATO2769.0[m]DCRRI2790.2[m]SWCSTATO2793.0[m]SWCSTATO2795.3[m]SWCSTATO2798.1[m]SWCSTATO2801.9[m]SWCSTATO2826.0[m]DCRRI2832.0[m]DCRRI2958.0[m]SWCSTATO3433.2[m]SWCSTATO3503.9[m]SWCSTATO