34/8-13 A
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General information
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Wellbore history
GeneralWells 34/8-13 A and 34/8-13 S were drilled in the Tampen Spur area of the North Sea. The objective of the wells was to the test the hydrocarbon potential in the Titan prospect. The prospect is located east of the Visund N2 Brent segment as part of the Visund N2 East Flank degradation complex, and contains two slide blocks, B and C. The primary objective of the 34/8-13A was to test the hydrocarbon potential of slide block B in the Titan prospect while the sidetrack 34/8-13 S, was drilled to test slide block C. For technical reasons the naming of these wells is reversed compared to usual practice: the A well is the main well while the S well is the geological sidetrack.Operations and resultsA 9 7/8" pilot hole, well 34/8 -U-1, was drilled from sea-bed to 725 m MD to evaluate for shallow gas. Based on MWD/LWD and ROV no indications of shallow gas were observed.Wildcat well 34/8-13 A was spudded with a 36" hole opener with the semi-submersible installation on Scarabeo 5 and drilled to TD at 3852 m (3132.7 m TVD) in Late Triassic sediments of the Statfjord Formation. No indications of shallow gas were observed when drilling the 36" and 26" hole in well 34/8-13 A. The well was drilled with seawater and hi-vis sweeps down to 1324 m, and with XP-07 oil based mud from 1324 m to TD.The well penetrated rocks of Quaternary, Tertiary, Cretaceous and Jurassic age. The Viking Group, Draupne Formation was encountered at 3349 m (2869.8 m TVD), and an intra Draupne Formation sandstone was encountered at 3386 m (2887.7 m TVD). Oil was discovered in the Intra-Draupne sandstone and down into degraded Brent sandstone. An oil leg of 19 m TVD was proven in the well position with oil down to 2905 m TVD and water up to 2907.5 m TVD. Oil shows were recorded only in the oil-bearing reservoir section and nowhere else in the well.Two cores were cut from 3416 to 3446 m in the Tarbert Formation. MDT oil samples were taken at 3398.5 m. The contamination from the OBM in these were 5.5 to 6 %wt. Analysis of the oil base in the mud filtrate proved a narrow cut of n-alkanes centred around C13.The well bore was plugged back on 13 May 2009 and a sidetrack (34/8-13 S) was drilled with KOP at 1346 m. Well 34/8-13 A was originally classified as an oil discovery. In June 2018 the well was reclassified as an appraisal well for the discovery 34/8-1 Visund.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]2950.003852.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13416.03438.1[m ]23439.03445.6[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]28.7Cores 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 typeCONDUCTOR30465.036468.00.00LOTPILOT HOLE725.09 7/8725.00.00LOTSURF.COND.201324.0261324.01.60LOTINTERM.9 5/82942.012 1/42948.01.80LOTOPEN HOLE3852.08 1/23852.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]MDT GRIT ACTS EDTC33833383MDT GRIT ACTS EDTC33953460MWD LWD - ARCVRES PP406725MWD LWD - ARCVRES6 TELE29423580MWD LWD - ARCVRES9 PP4692948MWD LWD - ECO TELE STHET SEISMIC29483852MWD LWD - PP406469SONIC OBMI29423744 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit40511201217185718571905192920502050227730453326332633493349338134143414344334663466349535933735 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured9681.3048.0KCl/Polymer13241.4818.0XP-07 - #1413301.3048.0KCl/Polymer13301.4115.0XP-07 - #1413301.3048.0KCl/Polymer13301.3017.0Kill Fluid- SW/Bentonite13971.4115.0XP-07 - #1423451.4821.0XP-07 - #1426171.4921.0XP-07 - #1429481.4924.0XP-07 - #1434391.6126.0XP-07 - #1438521.6130.0XP-07 - #1438531.6127.0XP-07 - #14