16/1-11
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General information
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Wellbore history
GeneralWell 16/1-11 was drilled to appraise the 16/1-9 discovery on the Gudrun Terrace just west of the Utsira High in the North Sea. The discovery well 16/1-9 was completed in April 2008 and revealed oil shows in the Middle Jurassic Vestland Group, but neither coring or logging was completed according to programme due to hole problems. The extent and reservoir quality of the Sleipner Formation in the Vestland Group was a primary objective in the data acquisition programme for 16/1-11 and an extensive wire line logging suite was planned in order to get as much information as possible regarding the oil-water contact, depth conversion, reservoir thickness, facies, fluids, well productivity and possible barriers in the reservoir. The Sleipner Formation reservoir was prognosed to be 75 m thick and coring of the hydrocarbon bearing part of the reservoir was decided prior drilling. Planned TD was TD at 2579 m, approximately 100 metres below prognosed base of the Sleipner Formation.Operations and resultsWell 16/1-11 was spudded with the semi-submersible installation Songa Delta on 23 February 2010. The 8 1/2" section in was drilled to TD at 2625 m in the Skagerrak Formation. After logging problems with setting and cementing the 7" liner made it necessary to make a sidetrack, 16/1-11T2, in order to do a drill stem test. The 8 1/2" sidetrack was kicked off from 2193 m and drilled to 2532 m (2523 m TVD). The sidetrack was drilled deviated with up to 20 deg deviation at its TD. The well was drilled with seawater down to 603.5 m, with Aqua-drill mud with 6% glycol from 603.5 to 1770 m, and with Carbo-Sea oil based mud from 1770 m to TD.Hydrocarbons were proven in the Sleipner and Skagerrak formations. Top Sleipner Formation came in at 2380.5 m. It consisted of 20 m coarse fining upward sandstones and contained gas. Analysis of core and log data showed good reservoir quality with calculated average effective porosity of about 19% and an average gas saturation of 31%. The Net Pay/Gross was nearly 1.0. The Skagerrak Formation came in at 2400.5 m. The core and log analysis proved a much lower reservoir quality than in the Sleipner Formation, mainly due to carbonate cementation. No contacts could be interpreted from the logs but pressure data gave a gas/oil contact at 2377.8 m TVD MSL. The log and pressure evaluation showed oil down to 2438 m (2409 m TVD MSL) and water up to 2445 m (2416 TVD MSL) in the Skagerrak formation. There were no pressure barriers between the Sleipner and Skagerrak formations. The deepest oil staining and fluorescence was recorded at 2502.8 m.Five 90 ft cores were cut in the interval 2385.5 m to 2522 m with practically 100 % recovery. Fluid samples were taken with the RCI tool. Gas samples were taken at 2396 m and 2406 m while oil samples were taken at 2408.8 m and 2437.8. A water sample was taken at 2454.1 m.The well was plugged back for a geological sidetrack on 26 April as an oil and gas appraisal well.TestingOne DST was performed in the sidetrack. It was perforated from 2415 - 2425 m, underbalanced with TCP. It flowed 177 Sm3 oil /day through a 28/64" choke. The oil density was 0.835 g/cm3 and GOR was 127 Sm3/Sm. Initial formation pressure was 244.75 bar at reference depth 2377.8 m TVD MSL. Initial formation temperature at this depth (DST temperature) was 98 deg C. -
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]610.002625.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12385.52411.9[m ]22412.52439.1[m ]32439.52466.6[m ]42466.52494.4[m ]52494.12522.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]135.9Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Oil samples at the Norwegian Offshore Directorate
Oil samples at the Norwegian Offshore Directorate Test typeBottle numberTop depth
MD [m]Bottom depth
MD [m]Fluid typeTest timeSamples availableDST2445.002415.00OIL16.04.2010 - 00:00YES -
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 typeCONDUCTOR30196.536165.50.00LOTSURF.COND.20600.026603.00.00LOTINTERM.13 3/81764.517 1/21770.01.78LOTINTERM.9 5/82356.012 1/42361.00.00LOTLINER72530.08 1/22532.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.00024.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.098Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.0525 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]MARCH JAR TTRM GR RCI SAM23962437MRCH GYRO21732174MRCH GYRO22022204MRCH JAR TTR GR SBT23562625MRCH JAR TTR MREX ZDL CN23252625MRCH JAR TTRM DSL ZDL CN23562521MRCH JAR TTRM GR JRC GUNS00MRCH JAR TTRM GR JRC GUNS00MRCH JAR TTRM GR PERF23832489MRCH JAR TTRM GR SBT22182489MRCH JAR TTRM GR SBT23562625MRCH JAR TTRM GR SPOP24052454MRCH JAR TTRM GR XMAC C-STAR17602610MRCH JAR TTRM GR ZVSP5852615MWD LWD - BR GR REMP BHPR MECH23612625MWD LWD - GR REMP BHPR MECH1962361 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit141754811825825837939122616091738198819882022207521282171220222082208223322332267226723182381238124012401 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]txt0.00txt0.01 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2021.04SPUD MUD17531.3033.0CARBO TECH17701.3116.0AQUACOL KCL/POLYMER/GLYCOL21501.2421.0CARBO TECH21671.3029.0CARBO TECH22021.2431.0CARBO TECH23611.3018.0CARBO TECH24731.2426.0CARBO TECH26251.2121.0CARBO TECH