25/2-7
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General information
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Wellbore history
General Block 25/2 is located on the eastern margin of the Viking Graben towards the Bjørgvin Arch. The main targets for well 25/2-7 were the Middle Jurassic Vestland Group and the Early Jurassic Statfjord Formation, which were hydrocarbon bearing in the surrounding wells 25/2-4, 25/2-5 and 25/2-6. In addition possible Late Callovian sands, as in the 25/2 -4 well, constituted a second target.Operations and resultWildcat well 25/2-7 was spudded with the semi-submersible installation Borgsten Dolphin on 1 April 1982 and drilled to TD at 4110 m in the Early Jurassic Dunlin Group. Operations took 103 days including 13 days of down time. Four and a half days were lost due to WOW, 5.5 days due to rig compensator damage, and 3 days were lost due to a leaking pack off assembly in the 9 5/8" casing. No Callovian sands (Intra Heather Formation) were encountered. Of the two main objectives the Vestland Group was confirmed and tested as a reservoir. The Vestland Group sandstones were encountered at 3406 m, 174 m higher than prognosed. It was 389 m thick, which was thicker than expected, and it consisted of an upper and a lower interval. Massive beds of sandstone, locally slightly shaly or well cemented with some layers of black shales and coal were encountered in the upper interval from 3406 m to 3628 m. The gross thickness of this interval was 222 m and net thickness approximately 179 m. Porosity as estimated from cores 1 and 2 and logs ranged from 2.5 % to 21 % with an average of 12 %. Permeability in this zone was rather low (0.01 to 15.55 mD). The second zone was penetrated from 3628 m to 3795 m. This interval was composed of shales and sandstones alternating in a regular sequences of 15 to 20 m. Net thickness was approximately 77 m with a porosity ranging from 16 % to 21% based on logs. Some oil shows were recorded on cores 1 and 2 in the upper Vestland sand interval. They must be considered as residual shows as the reservoir is water bearing according to the logs. The RFT results confirmed this, showing a hydrostatic pressure gradient. Sandstones of the Statfjord Formation was not found. A silty/shaley interval at 3870 m, 198 m thick, was thought to be an equivalent of them, according to log correlation with the 25/2-5 well, but this was not supported by biostratigraphic data. Due to lack of seismic information at this level there was no incitement to drill deeper. A yellow direct florescence cut was observed on cuttings from this interval from 3917 m to 3920 m. Four conventional cores were cut in the well. Two were cut in the interval 3409 m to 3444 m in the Vestland Group (Sandstone with coals), two were cut in the Dunlin Group. Of the latter one was cut in shale from 3791 m to 3799 m and the other was cut at TD in red brown shale. One RFT fluid sample was taken at 3436.7 m (filtrate, formation water, and traces of oil), another at 3410 m (filtrate and formation water). The well was permanently abandoned on 12 July 1982 as a well with shows.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]220.004102.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13409.03414.0[m ]23424.53443.5[m ]33791.03798.0[m ]44101.04110.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]40.0Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory2450.0[m]SWCSNEA2550.0[m]SWCSNEA2789.0[m]SWCSNEA2850.0[m]SWCSNEA3050.0[m]SWCSNEA3135.0[m]SWCSNEA3150.0[m]SWCSNEA3220.0[m]SWCSNEA3265.0[m]SWCSNEA3270.0[m]SWCSNEA3275.0[m]SWCSNEA3380.0[m]SWCSNEA3398.0[m]SWCSNEA3409.0[m]CSPT3410.0[m]CSPT3412.0[m]CSNEA3413.5[m]CSPT3426.2[m]CSPT3427.3[m]CSNEA3428.6[m]CSPT3430.6[m]CSPT3431.5[m]CSNEA3434.3[m]CSPT3435.0[m]CSNEA3439.3[m]CSPT3630.0[m]SWCSNEA3701.0[m]SWCSNEA3791.1[m]CSPT3795.5[m]CSPT3797.6[m]CSPT3798.5[m]CSNEA4101.4[m]COD4103.3[m]COD4106.2[m]COD4109.0[m]COD -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit14110492023214921492189219423182475258932053263326332753406340634183628 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf1.75 -
Documents – reported by the production licence (period for duty of secrecy expired)
Documents – reported by the production licence (period for duty of secrecy expired) Document nameDocument formatDocument size [MB]pdf9.97 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BGT7272182BHC GR21983180CBL VDL3002198CBL VDL18003279CIS21983285CIS32794084CST21622183CST23453280CST33804080DLL MSFL33503630HDT21983285HDT32794084ISF GR BHC SL1384097LDT CNL GR CAL2014088NGST32794077RFT34083591VELOCITY1384097 -
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 typeCONDUCTOR30201.036203.00.00LOTSURF.COND.20727.026739.01.06LOTINTERM.13 3/82194.517 1/22210.01.17LOTINTERM.9 5/83275.012 1/43290.01.27LOTOPEN HOLE4110.08 1/24110.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2101.09spud mud5401.11water based7901.06water based16401.22water based22101.17water based29901.23water based32401.27water based36351.21water based -
Pressure plots
Pressure plots The pore pressure data is sourced from well logs if no other source is specified. In some wells where pore pressure logs do not exist, information from Drill stem tests and kicks have been used. The data has been reported to the NPD, and further processed and quality controlled by IHS Markit.Pressure plots Document nameDocument formatDocument size [MB]pdf0.23