15/9-23
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General information
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Wellbore history
GeneralWell 15/9-23 was drilled in the southern Viking Graben, south of the Sleipner East Field in the North Sea. The primary objective was to test the Middle Jurassic Hugin and Sleipner formations and the Triassic Skagerrak formation within the Skardkollen prospect. The Early Paleocene Ty Formation was secondary objective.Operations and resultsWildcat well 15/9-23 was spudded with the semi-submersible installation Bredford Dolphin on 18 November 2009 and drilled to TD at 3225 m in late Triassic sediments of the Skagerrak Formation. A 9 7/8" pilot hole was drilled from the 36" section to 714 m and a shallow gas zone was encountered at 674 to 678 m. The hole was opened to 26" down to 556 m, and 20" casing was set at 550 m. The well was drilled with seawater and hi-vis sweeps down to 556 m, with KCl/Glycol mud from 556 to 1520 m, and with XP-07oil based mud from 1520 m to TD.The top of the first Frigg Formation sand was penetrated at 2092 m. The secondary target, the Ty Formation of the lowermost Rogaland Group was penetrated at 2524 m. The Ty Formation constituted excellent reservoir sandstones with a gross thickness of 24 m. GeoTap pressure measurements detected a pore pressure depletion of 105 bar compared to a normal hydrostatic gradient, most likely related to production at the nearby Sleipner East Field within the same stratigraphical unit. The primary reservoir target, the Middle-Jurassic Vestland Group, was penetrated at 3087.5 m, 45.5m deeper than anticipated. The Hugin Formation was absent, and the top of the Vestland Group consisted of the coal-bearing Sleipner Formation. Firm identification of red-brown Triassic mudstones of the Skagerrak Formation was penetrated at 3169 m, 5.5m shallower than prognosed. GeoTap pressure measurements through the Sleipner- and Skagerrak Formations also detected higher overpressures (65-73-89 bar) than measured in the nearby, analogue wells. The high and vertically varying overpressures, in combination with the low N/G and inferred poor/non-effective sand-to-sand connectivity, may explain the failure of hydrocarbons migrating into the Skardkollen structure.All reservoirs were water-wet. The only show recorded in the well was a very weak show on cuttings in the Sleipner Formation. Lack of supportive from logs and gas levels suggested that the show could be caused by the drilling fluid.No cores were cut. No logs were run on wire line, all logs are from LWD. No fluid samples were taken.The well was permanently abandoned on 3 January 2010 as a dry well.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]640.003225.00 -
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 typeCONDUCTOR30175.036178.00.00LOTSURF.COND.20550.026713.01.65LOTINTERM.13 3/81519.017 1/21525.01.95LOTINTERM.9 5/82998.012 1/43005.02.10LOTOPEN HOLE3225.08 1/23225.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]MWD LWD - DIR109178MWD LWD - EWR GR PWD ALD CAL CNT30043225MWD LWD - GR RES ALD CTN BAT GEO15253004MWD LWD - GR RES PWD DIR1781523 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit110891113312711285209221102137216123232323234524172524254825482551273028112858288928892898291729292938293830383087308731693169 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1091.04Spud mud1781.04Spud mud1991.30Seawater5021.04Spud mud5471.2011.0KCl/GEM7141.25Spud mud11451.2223.0KCl/GEM13801.2022.0KCl/GEM25891.2520.0XP-0730041.3522.0XP-0732251.3621.0XP-07