34/6-5 S
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General information
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Wellbore history
GeneralWell 34/6-5 S was drilled to test the Garantiana West prospect in the Northern part of the Tampen Spur in the North Sea. The primary objective was to prove oil and establish the oil-water contact in the Early Jurassic Cook Formation. Secondary objective was the Nansen Formation. In case of discovery a Drill Stem Test would be carried out.Operations and resultsWildcat well 34/6-5 S was spudded with the semi-submersible installation West Hercules on 18 March 2021 and drilled to TD at 4036 m (3982.8 m TVD) m in the Early Jurassic Cook Formation. Drilling started with a data acquisition 8 1/2' pilot hole drilled down to 1350 m, lithology in this interval is based on logs from this hole. No shallow gas was seen in the pilot hole. The main well was drilled vertical to 2800 m, building to a ~19 inclination from 3203 m and keeping same until TD. After reaching TD, the BHA got stuck while pulling out of hole at 3806 m. It was decided to drill a technical side-track to perform the wireline program on the Cook Formation and the Drill Stem Test operations. The 34/6-5 S T2 well was side-tracked from the 9 5/8" liner, through a milled window at 3474 m to 3480 m. It was drilled to a total depth of 3833 m (3781 m TVD) in the Burton Formation. The 34/6-5 S well was drilled with seawater and hi-vis pills down to 1370 m, with Versatec oil-based mud from 1370 m to 3535 m, and with Exploradrill oil-based mud from 3535 m to TD. The 34/6-5 S T2 well was drilled with Exploradrill oil-based mud from kick-off to 3833 m.Top of Cook Formation was encountered with oil at 3651 m (3619 m TVD). Pressure data and fluid sample densities indicated the oil-water contact to be at 3747.5 m (3703 m TVD). Pressure measurements indicate a similar pressure regime as found in the 34/6-3 A Akkar well. Sandstones in the Nansen Formation were water bearing. Apart from the hydrocarbon bearing Cook Formation there were no shows in the well.Two cores were cut in succession from 3695 to 3766.5 m in the side-track with 97.7 and 101% recoveries respectively. MDT fluid samples were taken at 3641. 4 m (oil with 4.5% - 5.0% mud contamination) and 3709.3 m (water).The well was permanently abandoned on 8 June 2021 as an oil discovery.TestingA DST was conducted in the Cook Formation in the side-track. The perforated interval was from 3673.97 - 3734 m (3636 3691 m TVD). The well flowed 550 Sm3/day during the main flow. PVT analysis gave a flash GOR of 79 Sm3/Sm3 and a STO oil density of 0.88 g/cm3. -
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]1380.004036.60 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13662.83694.3[m ]23694.33765.8[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]103.0Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit41612621872187219081916203020412041224732073368336833763396340634743529352936543772 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0367437340.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.05500.88079 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]LWD - GR ECD RES DI35354036LWD - GR ECD RES SON DEN NEU DI24293535LWD - GR RES DI4351370LWD - GR RES DI ECD13702429LWD - GR RES NEU DEN DI4161350PEX AIT MSIP13602418XPT GR36303657 -
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.201363.0260.00.00INTERM.13 5/82420.017 1/22429.01.83LOTLINER9 5/83534.012 1/43484.02.02LOTLINER73831.08 1/23833.00.00OPEN HOLE4036.08 1/24036.00.00 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured13601.3937.08.5Versatec16101.4742.012.0Versatec24291.6052.011.0Versatec24291.4744.012.0Versatec25571.6051.010.5Versatec30231.6155.013.5Versatec31431.6356.013.5Versatec33821.6763.013.5Versatec34751.8439.08.0Exploradrill35331.8240.010.5Exploradrill35351.7268.012.0Versatec36551.8432.09.5Exploradrill36621.8531.08.0Exploradrill38311.7236.06.5Exploradrill38331.8239.09.0Exploradrill38741.8536.06.5Exploradrill40361.8538.09.0Exploradrill