15/12-20 S
Export:
PDF
![PDF icon](https://factpages.sodir.no/Images/file-pdf.png)
-
General information
-
Wellbore history
GeneralWell 15/12-20 S was drilled from the Varg Field production Platform in the southern Viking Graben in the North Sea. The primary objective of the well was to explore a potential undrained compartment in Triassic sands. A secondary objective was potential Late Jurassic sands that could exist above the Triassic sands.Operations and resultsWildcat well 15/12-20 S was drilled with the jack-up installation Mærsk Giant, as a sidetrack from development well 15/12-A-7 on the Varg Field. It was kicked off 28 May 2008 from 1306 m, just above the 13 3/8" casing in the 15/12-A-7 development well, and drilled to TD at 4192 m (3142 m TVD) in the Late Triassic Skagerrak Formation. Significant operational problems were not encountered although 21% of the rig time was counted as non-productive. The main contributor to non-productive time was failure to mill the window in the 13 3/8" casing during kick-off. The well was drilled with Carbo-Sea oil based mud from kick-off to TD.The Oxfordian Sandstone that makes up the reservoir over Varg Field was absent as forecast. A discovery was made in Middle Jurassic Sleipner Formation sandstone. This sand, encountered at 3808 m, was not prognosed. It contained oil down to a lithological contact at ca 3842 m (2878 m TVD SS). The underlying Triassic was encountered at 3874 m and was dry. Good shows on sandstones were reported in cuttings at 3810 and all through to the end of the cores at 3875 m. Formation Gas peaks up to a maximum of 4% were seen in the Sleipner formation. Resistivity was initially high, 15 ? 30 ohm/m from 3812 m (after the coal) and dropped off at 3835m MD to 0.3 - 0.8 ohm/m.Two cores were taken (26.26 m and 54.85 m) from the Sleipner Formation and ca 25 m into the Triassic. Reservoir pressures were taken using TesTrak and an oil gradient of 0.935 SG was obtained although a water gradient was not established. No wire line fluid samples were taken.Exploration well 15/12-20 S is classified as an oil discovery. On 1 July 2008 7" liner was run to 4191 m and the well was reclassified to development well 15/12-A-7-A.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]1310.004192.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13815.03841.2[m ]23843.03897.9[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]81.1Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
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 typeINTERM.9 5/83370.012 1/43375.01.70LOTLINER74191.08 1/24192.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]MWD LWD - DIR13041336MWD LWD - DIR RES GR CCN MT ST T38984192MWD LWD - DIR RES GR PWD13363815 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit13613052906290629243022317632693269343236553699369937473791379137973808380838743874 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured12501.4638.0oil based12901.4632.0oil based12971.5940.0water based13031.5938.0water based13131.5940.0water based13161.5944.0water based13331.6048.0water based13361.5939.0water based13481.5952.0water based13541.6051.0water based13731.5957.0water based14741.5343.0water based17501.5943.0water based31711.5945.0water based33751.6043.0water based36131.4430.0water based38431.4432.0water based38981.4532.0water based41361.4533.0water based41921.02water based41921.4431.0water based