General information Attribute ValueWellbore name25/2-18 STypeEXPLORATIONPurposeWILDCATStatusP&APress releaseFactmaps in new windowMain areaNORTH SEADiscoveryWell name25/2-18Seismic locationDN13303-04010. SP 1295 / DN13303-02005. SP 1214Drilled in production licenceDrilling operatorDet norske oljeselskap ASADrill permit1634-LDrilling facilityDrilling days36Entered date06.08.2016Completed date11.09.2016Release date11.09.2018Publication date11.09.2018Purpose - plannedWILDCATReentryNOContentOILDiscovery wellboreYES1st level with HC, ageMIDDLE JURASSIC1st level with HC, formationHUGIN FMKelly bushing elevation [m]55.0Water depth [m]121.0Total depth (MD) [m RKB]3887.0Final vertical depth (TVD) [m RKB]3877.0Maximum inclination [°]8.8Bottom hole temperature [°C]129Oldest penetrated ageEARLY JURASSICOldest penetrated formationDRAKE FMGeodetic datumED50NS degrees59° 49' 30.11'' NEW degrees2° 37' 54.1'' ENS UTM [m]6632137.57EW UTM [m]479347.43UTM zone31NPDID wellbore8023
Wellbore historyGeneralWell 25/2-18 S was drilled to test the Langfjellet prospect on the Bjørgvin Arch, four kilometers south of the 25/2-10 S (Frigg Gamma Delta) oil/gas discovery and eight kilometers north of the shutdown Frøy field in the North Sea . The objective of well 25/2-18 S was to prove petroleum in Middle Jurassic reservoir rocks belonging to the Vestland Group (the Hugin and Sleipner formations) .Operations and resultsWildcat well 25/2-18 S was spudded with the jack-up installation Mærsk Interceptor on 6 August 2016 and drilled to TD at 3820 m (3812.7 m TVD). A technical sidetrack, 25/2-18 ST2, was kicked off from 25/2-18 S at 3345 m. The sidetrack was drilled in order to perform data acquisition in accordance with NPD regulations. The sidetrack was drilled to final TD at 3887 m in the Early Jurassic Drake Formation. No significant problem was encountered in the operations. The well was drilled with seawater and hi-vis sweeps down to 450 m and with Versatec oil based mud from 450 m from 450 m to TD.Top of target reservoir, Hugin Formation, was penetrated at 3431.5 m (3424.2 m TVD) in 25/2-18 S, and at 3433 m (3424.9 m TVD) in the 25/2-18 ST2 sidetrack. In the sidetrack, the formation had a gross oil column of 125 m with a down-to contact at 3563 m (3554 m TVD). Net-to-gross of the Hugin Formation is 0.46 in well 25/2-18 S and 0.69 in the sidetrack. The difference in net-gross is due to a higher degree of cementation in well 25/2-18 S than in the sidetrack. The two boreholes penetrate the Hugin Formation ca 15 m away from each other.The OBM produced a show of weak, dull, light yellow, direct fluorescence and fair, cut fluorescent. Due to this, and overbalanced drilling and structure destroying effects of PDC bits, shows on cuttings are unreliable. The sidetrack had good shows on conventional cores over most of the interval from 3431 to 3540 m in the oil-bearing reservoir.In the sidetrack, two cores were cut in the interval 3427 m to 3553 m, and seven wireline logging runs were performed. Fluid samples were taken in the sidetrack at 2123.89 m, 3449.7 m, 3482.7 m, 3524.8 m and 3544.4 m.The well was plugged back for geological sidetracks on 11 September 2016. It is classified as an oil discovery.TestingNo drill stem test was performed.
Cuttings at the NPD
Cuttings at the NPDCuttings available for sampling?YES Cuttings at the NPDCutting sample, top depth [m]Cutting samples, bottom depth [m]460.003820.00
Cores at the NPD
Cores at the NPDCore sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13427.03482.0[m ]23482.43555.1[m ] Cores at the NPDTotal core sample length [m]127.7 Cores at the NPDCores available for sampling?YES
LithostratigraphyTop depth [m]Lithostrat. unit176506642642144615422118212821282204224023262542261626162653288330773194320132253225326532983298337934323432355737833783
LogsLog typeLog top depth [m]Log bottom depth [m]LWD - DI GR PWD222450LWD - DI GR RES PWD4501541LWD - DI GR RES PWD NEU DEN SON15413820LWD - DI PWD GR RES NEU DEN CAL176450RES SON PWD DEN NEU SPECGR4421525T2 - MDT MINIDST21173573T2 - MDT MINIDST34823482T2 - PRP DIEL LITHO MAG RES20653727T2 - RES SON PRESS DEN NEU SP GR14641905T2 - RES ZAIT GPIT PPC20653872T2 - SON DEN NEU SP GR17803886T2 - ZOVSP4513668T2 LWD - DI GR RES PWD33453427T2 LWD - DI GR RES PWD34273887
Casing and leak–off tests
Casing and leak–off testsCasing typeCasing diam.
[m]LOT/FIT mud eqv.
[g/cm3]Formation test typeCONDUCTOR30222.036214.00.00SURF.COND.20444.526450.01.32LOTPILOT HOLE450.09 7/8450.00.00INTERM.13 3/81533.5161541.01.58FITOPEN HOLE3887.08 1/23887.00.00
Drilling mudDepth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured6651.1722.0Versatec OBM15401.1921.0Versatec OBM20691.2421.0Versatec OBM33851.2921.0Versatec OBM38871.2922.0Versatec OBM38871.3027.0Versatec OBM