25/11-15
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General information
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Wellbore history
GeneralWell 25/11-15 was drilled east of the Balder Field complex on the Utsira High in the North Sea. The main objective was to test the hydrocarbon potential of the Paleocene Heimdal Sand in the Hermod prospect.Operations and resultsWildcat well 25/11-15 was spudded with the semi-submersible installation Transocean 8 on 10 November 1991 and drilled to TD at 2035 m in the Early Jurassic Statfjord Formation. Due to shallow gas warning an 8 1/2" pilot was drilled from 239 to 390 m. No shallow gas was found. The well was drilled with seawater and viscous bentonite sweeps down to 1312 m and with KCl/PHPA/Polymer mud from 1312 m to TD.The Balder Formation was encountered at 1660 m. It contained rare sandstone stringers close to the top and these had good oil shows. This was the only oil show recorded outside of the Heimdal Formation. A 64 m thick Heimdal Formation Sandstone was penetrated from 1734 m to 1798 m. The sandstone was oil bearing down to a well-defined OWC at 1787 m. The net pay thickness was 51.88 m with an average porosity of 34.5% and an average Sw of 12.5%.Seven cores were cut from 1680 m to 1799 m, starting 7 m below the top Sele Formation and ending 1 m below the base of the Heimdal Formation. A total of 20 good RFT pressure points were recorded giving a fluid density of 0.86 g/cc in the hydrocarbon bearing zone. Two fluid samples were attempted, but were abandoned after problems with sand plugging.The well was permanently abandoned on 25 December 1991 as an oil Discovery.TestingA single production test was performed over the interval 1736 - 1775 m in the Heimdal Formation. The well flowed 525 Sm3 oil and 7500 Sm3 gas /day through a 25.4 mm choke. The GOR was 14 Sm3/Sm3 and the oil was 0.940 g/cm3. The gas gravity was 0.640 with 0.3% CO2 and 0.2 ppm H2S. The bottom hole temperature, recorded at 1695.08 m gauge depth, was 76.6 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]1320.002035.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11680.01696.0[m ]21696.81705.8[m ]31708.01728.0[m ]41728.01740.0[m ]51740.51762.6[m ]61762.61781.1[m ]71781.11796.6[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]113.1Cores 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 typeLaboratory1325.0[m]SWCHYDRO1350.0[m]SWCHYDRO1375.0[m]SWCHYDRO1425.0[m]SWCHYDRO1460.0[m]SWCHYDRO1485.0[m]SWCHYDRO1495.0[m]SWCHYDRO1497.0[m]SWCHYDRO1570.0[m]SWCHYDRO1605.0[m]SWCHYDRO1617.0[m]SWCHYDRO1640.0[m]SWCHYDRO1652.0[m]SWCHYDRO1675.0[m]SWCHYDRO1678.0[m]SWCHYDRO1680.0[m]CHYDRO1684.0[m]CHYDRO1689.0[m]CHYDRO1694.0[m]CHYDRO1696.9[m]CHYDRO1703.0[m]CHYDRO1707.0[m]SWCHYDRO1708.2[m]CHYDRO1713.0[m]CHYDRO1717.0[m]CHYDRO1722.0[m]CHYDRO1726.4[m]CHYDRO1730.9[m]COD1732.0[m]CHYDRO1732.8[m]COD1735.6[m]CHYDRO1741.2[m]CHYDRO1749.0[m]CHYDRO1756.0[m]CHYDRO1764.0[m]CHYDRO1770.5[m]CHYDRO1777.5[m]CHYDRO1784.9[m]CHYDRO1784.9[m]COD1791.4[m]CHYDRO1792.8[m]CHYDRO1796.0[m]CHYDRO1815.0[m]SWCHYDRO1850.0[m]SWCHYDRO1952.0[m]SWCHYDRO1964.0[m]SWCHYDRO1988.0[m]SWCHYDRO1989.3[m]SWCHYDRO1990.8[m]SWCHYDRO -
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 availableDSTDST11736.001775.0018.12.1991 - 00:00YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit151652750798798101810321108149115061660166016741678173417981807181818181867189319041926192619421954197819781983 -
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]pdf17.18 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01736177425.4Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.076Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.052575000.9400.64014 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CST12902006DIL LSS GR SP AMS2381259DIL LSS GR SP AMS12742018DLL MSFL LDL CNL NGL SP AMS12742016MWD - GR RES DIR1502035RFT GR AMS14851504RFT GR AMS16611997RFT GR AMS17351736SHDT GR AMS12742021VSP5702010 -
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 typeCONDUCTOR30237.036240.00.00LOTINTERM.9 5/81273.012 1/41275.01.71LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2381.2019.08.0WATER BASED12.11.19912391.2019.08.0WATER BASED12.11.19914501.2018.04.0WATER BASED13.11.199113121.2018.09.0WATER BASED14.11.199113121.2219.015.0WATER BASED19.11.199113121.2019.011.0WATER BASED19.11.199113121.2018.08.0WATER BASED15.11.199115301.1320.014.0WATER BASED19.11.199116971.1517.08.0WATER BASED19.11.199117261.1616.09.0WATER BASED20.11.199117261.1616.09.0WATER BASED22.11.199117681.1915.09.0WATER BASED28.11.199117691.2014.011.0WATER BASED29.11.199117691.2014.012.0WATER BASED02.12.199117691.3520.014.0WATER BASED02.12.199117691.2915.09.0WATER BASED02.12.199117691.2915.010.0WATER BASED03.12.199117691.2915.09.0WATER BASED04.12.199117691.2113.07.0WATER BASED05.12.199117761.2617.016.0WATER BASED06.12.199117761.2719.014.0WATER BASED10.12.199117761.2718.013.0WATER BASED10.12.199117761.2718.014.0WATER BASED11.12.199117761.2614.013.0WATER BASED11.12.199117761.2614.013.0WATER BASED13.12.199117761.2614.013.0WATER BASED16.12.199117761.2614.013.0WATER BASED16.12.199117761.2614.013.0WATER BASED17.12.199117761.2614.013.0WATER BASED18.12.199117761.2514.013.0WATER BASED19.12.199117761.2514.013.0WATER BASED20.12.199117761.2512.010.0WATER BASED23.12.199117761.2819.015.0WATER BASED10.12.199117761.2614.013.0WATER BASED12.12.199117761.2614.013.0WATER BASED16.12.199117811.1516.09.0WATER BASED22.11.199117811.1516.09.0WATER BASED21.11.199119061.1818.011.0WATER BASED22.11.199120351.1816.010.0WATER BASED25.11.199120351.1816.09.0WATER BASED27.11.199120351.1617.010.0WATER BASED25.11.199120351.1714.08.0WATER BASED25.11.199120351.1817.010.0WATER BASED26.11.1991 -
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