16/1-25 S
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General information
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Wellbore history
GeneralWell 16/1-25 S was drilled on the Utsira High in the North Sea, 2.7 km south of well 16/1-12 (Rolvsnes discovery well). The primary objective was to prove the presence of transgressive Cretaceous and/or Jurassic sandstones overlying the basement and to test the extension of the 16/1-12 discovery in porous basement towards south.Operations and resultsWildcat well 16/1-25 S was spudded with the semi-submersible installation Bredford Dolphin on 15 October 2015 and drilled to TD at 2210 m (2121 m TVD) m in the basement rock. The section from 2010 to 602 m was drilled first as a 97/8” pilot hole to check for shallow gas and then opened up with a 26” bit. No shallow gas was observed. The well was drilled as a deviated well (15° through basement) in order to cross more faults and test a wider area and in that way to get better control on variability, quality and thickness of the weathered zones. Operations proceeded without significant problems. The well was drilled with seawater and hi-vis sweeps down to 602 m and with Aquadril mud from 602 m to TD.A 10 m transgressive sandstone was prognosed at the base of the Early Cretaceous Åsgard Formation but only 10 cm was observed directly above basement. The top basement was found at 2004.25 m (1922.7 m TVD). The well encountered an oil column of about 30 m in porous and fractured basement rock. The OWC is set 2034.5 m MD RKB (1952 m TVD). The pressure data shows communication with the 16/1-12 oil discovery, with approximately the same oil/water contact. The fluid type is oil with similar properties to the Edvard Grieg oil. Below OVC there was oil shows (direct, cut and residual fluorescence) down to 2067 m, and weaker shows down to 2124 m. There were no shows below this depth or above top Basement.Six Cores were cut in succession in the basement from 2002 to 2025.23 m with a total recovery of 97%. The core-log shift varies between 0.07 and 0.342 m. MDT fluid samples were taken at 2012.25 m (oil), 2032.5 m (oil), and 2059.6 m (water). PVT single flash analyses of the samples from 2012.25 m gave GOR in the range 175 to 197 Sm3/Sm3 and oil density in the range 0.847 to 0.849 g/cm3. The samples from 2032.5 m had GOR in the range 168 to 177 Sm3/Sm3 and oil density in the range 0.851 to 0.852 g/cm3.The well was permanently abandoned on 26 December 2015 as an oil appraisal.TestingOne production test (DST) was performed in the oil zone from 2006.83 to 2029.26 m. The test produced 47 Sm3 oil and 13300 Sm3 gas per day through a 32/64“ choke. The GOR was 280 Sm3/Sm3. The DST temperature measured at 2019.9 m (1937.8 m TVD) was 77.4°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]610.002209.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12002.02006.0[m ]22006.02007.6[m ]32008.02010.8[m ]42010.82013.3[m ]52013.42018.6[m ]62018.82025.2[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]22.5Cores 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 typeCONDUCTOR30210.036210.00.00SURF.COND.20596.026602.01.55FITPILOT HOLE602.09 7/8662.00.00INTERM.9 5/81922.412 1/41930.01.96LOTLINER72208.08 1/22210.00.00 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.02007202914.3Drill 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]1.04713300280 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CMR MRF ADT XPT GR JARS20102200FMI PPC MSIP GR JARS19222210MDT PS HY PO SRP PQ IFA MS GR JA20122100MFI GR19222210MWD LWD - DIR ECD GR130602MWD LWD - DIR ECD GR RES SON182600MWD LWD - RES GR ECD18882000MWD LWD - RES GR ECD DEN NEU SON5592210UIB HRLA PEX ECS HNGS19222205VSI32 GR6102189XL ROCK20262039XL ROCK20452171 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1317341006101417041788178817951820191019171917193419811999199920002004 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1311.4020.0Spud Mud2101.0410.0Spud Mud2101.4010.0Spud Mud3851.4016.0Water Based3981.0410.0Spud Mud6021.0310.0Spud Mud6021.3519.0Water Based6021.4015.0Spud Mud12971.3916.0Water Based15681.4023.0Water Based15681.2010.0Water Based15911.4020.0Water Based19621.2018.0Water Based22101.202.0Brine22101.2016.0Water Based