25/8-1
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General information
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Wellbore history
GeneralWell 25/8-1 was drilled on the Utsira High in the North Sea. The main purpose was to test an Eocene structural closure, up dip from oil-bearing Eocene sands in Well 25/11-1.Operations and resultsWildcat well 25/8-1 was spudded with the vessel Glomar Grand Isle on 28 April 1970. Drilling operations were normal down to 2606 m, which became TD in the well, 289 m into the Early Permian Undefined Group. While drilling at this depth the drilling pipe parted. After recovering the upper portion of the drill pipe the top of the portion left in the hole was found to be at 2559. Attempts to recover the fish failed and after logging and taking sidewall cores in the uncased hole the well was prepared for testing. Initial drilling from the sea floor to 378 m was with sea water and gell. Below 378 m to 1311 m, the mud system consisted of sea water, spersene XP-20 salinex. From 1311 m to TD fresh water, spersene XP-20 mud was used.The well penetrated several Tertiary sands above the Paleocene (Utsira and Skade Formations). These sands were water wet, but some methane was recorded in the upper part of the Utsira Formation. Two Paleoocene sands (Hermod Formation at 1754.4 - 1758.1 m and 1759.0 - 1763.0 m) were found. The sands were separated by a thin 1 m shale section. Upon testing, the sands were found to be capable of producing approximately 429 Sm3 of 21.7 deg API gravity, low sulphur (0.77 to 0.80%) oil per day. All other sands or reservoirs penetrated by the well, including the Heimdal Formation at 1777 to 1812 m, were water wet without shows.Seven cores were cut in the well. Core no 1 was cut from 1676.4 to 1684.9 m in the Balder Formation, cores no 2 to 5 were cut in the interval 1724.3 to 1790.7 m in the Balder/Sele/Hermod/Sele/Lista/Heimdal Formations, core no 6 was cut at 1828.8 to 1847.1 m in the Lista/Våle Formations, and core no 7 was cut at 2359.2 to 2377.4 m in the Undefined Group. FIT wire line fluid samples were taken at 1756.6 m (5.5 gallons oil), 1760.5 m (5 gallons oil), and at 1783.1 m (5 gallons water). The oil gravity was 21.7 and 21.8 deg API with 0.77% and 0.80%, respectively.The well was permanently abandoned on 4 July 1970 as an oil discovery.TestingA production test performed in the interval 1755.0 to 1762.4 m in the Hermod Formation sand. The well was tested in four successive flow periods of increasing drawdown pressures. The final flow period lasted about 19 hours; during this period the average rate was about 429 Sm3/day through a 64/64" choke. The GOR was 23.2 Sm3/Sm3 (130 ft3/barrel), oil gravity was 21 deg API. Only trace quantities of basal sediments and water were produced during the test. No sand was detected in the produced fluid sampled at the surface; however, a small quantity of fine-grain sand was removed from the bottom-hole fluid samplers. -
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]2407.922603.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom15500.05528.0[ft ]25657.05715.0[ft ]35713.05770.0[ft ]45770.05815.0[ft ]55815.05875.0[ft ]66000.06060.0[ft ]77740.07794.0[ft ]Cores at the Norwegian Offshore Directorate Total core sample length [m]110.3Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory6360.0[ft]DCRRI6400.0[ft]DCRRI6440.0[ft]DCRRI6480.0[ft]DCRRI6500.0[ft]DCRRI6510.0[ft]DCRRI6520.0[ft]DCRRI6530.0[ft]DCRRI6540.0[ft]DCRRI6550.0[ft]DCRRI6560.0[ft]DCRRI6570.0[ft]DCRRI6600.0[ft]DCRRI6610.0[ft]DCRRI6640.0[ft]DCRRI6650.0[ft]DCRRI6680.0[ft]DCRRI6700.0[ft]DCRRI6720.0[ft]DCRRI6760.0[ft]DCRRI6760.0[ft]DCRRI6800.0[ft]DCRRI6800.0[ft]DCRRI6840.0[ft]DCRRI6880.0[ft]DCRRI6920.0[ft]DCRRI6960.0[ft]DCRRI7000.0[ft]DCRRI7040.0[ft]DCRRI7080.0[ft]DCRRI7120.0[ft]DCRRI7160.0[ft]DCRRI7200.0[ft]DCRRI -
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 availableDSTTEST11762.001755.0030.06.1970 - 00:00YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1386077167507509709911015106210931663166516651736175417631767177718121841184618461853189719151923193619811981198721582317 -
Geochemical information
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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]pdf1.55pdf38.47 -
Documents – Norwegian Offshore Directorate papers
Documents – Norwegian Offshore Directorate papers Document nameDocument formatDocument size [MB]pdf18.56pdf1.40pdf0.48pdf0.41 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01755176225.4Drill 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]1.042999650.93023 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BHC SON GR CAL3892540DIP3892083FDC13282540GR134389IES3892548MLL CAL3891915VELOCITY1352600 -
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 typeCONDUCTOR30163.036165.00.00LOTSURF.COND.20390.026405.00.00LOTINTERM.13 3/81330.0181346.00.00LOTINTERM.9 5/81881.012 1/41903.00.00LOTOPEN HOLE2606.08 1/22606.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured3781.05seawater13101.07sw/sper26191.04fw/sper -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit1754.00[m ]1754.00[m ]1755.00[m ]1756.00[m ]1754.00[m ]5866.00[ft ]5845.00[ft ]5862.00[ft ]5875.00[ft ]6042.50[ft ]5776.50[ft ]5869.00[ft ]5836.00[ft ]5773.00[ft ]5825.50[ft ]7767.00[m ]7740.00[ft ] -
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]pdf0.21