25/8-10 S
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General information
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Wellbore history
GeneralWell 25/8-10 S is located north of the Grane Field. The well was drilled and tested to obtain representative fluid samples, production characteristics, and reservoir permeabilities in the Forseti Prospect in the Hermod - Middle Heimdal formation.Operations and resultsExploration well 25/8-10 S was spudded with semi-submersible drilling installation "Deepsea Trym" on 29 April 1997 and drilled to TD at 1749.5 m in the Late Paleocene Lista Formation. The original 25/8-10 S well was drilled with a slightly deviated profile (+/- 6 degree maximum angle) to a depth of 1749 m MD RKB. Due to a mechanical problem, which occurred after coring at 1722-1749 m, the well was plugged back and a technical sidetrack (25/8-10S T2) was kicked off at 1076 m and drilled to the original geologic objective at a total depth of 1890 m in the Early Paleocene Ekofisk Formation. Well 25/8-10 S was drilled with seawater and bentonite sweeps down to 1091 m and with oil based "Ancovert" mud from 1091 m to TD. The technical sidetrack 25/810 S T2 was drilled with oil based with "Ancovert" mud. The sidetrack penetrated 18 m (net pay) of oil filled sand in the Hermod - Middle Heimdal formation with an OWC, based on logs, at 1755.5 m TVD SS. The pay zone consisted of three sand intervals. One core was cut in the 25/8-10 S wellbore in the interval 1722 m to 1749.65 m (Sele, Hermod, and Lista Formations). A second core was cut in the 25/8-10 S T2 sidetrack in the interval 1749 m to 1786 m. (Lista and Heimdal Formations). After wire line logging the 25/8-10S T2 well a drill stem test of the upper sand interval, in the Hermod Formation, was performed. Fluid samples were taken during the DST. The well was permanently abandoned on 5 June 1997 as an oil and gas discovery, named the 25/8-10 S Ringhorne Discovery.TestingThe interval from 1727.0 m to 1740.5 m (1698.6 - 1711.9 m TVD SS) in the Hermod Formation was perforated. The test showed an unconsolidated reservoir with high porosity. The GOR at rate 445 Sm3 fluid/day increased roughly from 45 Sm3/Sm3 to 90 Sm3/Sm3 as the wellhead pressure increased from 600 to 800 psia. This was considered consistent with the presence of a gas cap. -
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]1100.001890.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11722.01749.7[m ]21749.01786.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]64.7Cores 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 typeLaboratory1110.0[m]DCCGG1130.0[m]DCCGG1150.0[m]DCCGG1160.0[m]DCCGG1170.0[m]DCCGG1190.0[m]DCCGG1200.0[m]DCCGG1220.0[m]DCCGG1230.0[m]DCCGG1240.0[m]DCCGG1250.0[m]DCCGG1260.0[m]DCCGG1270.0[m]DCCGG1280.0[m]DCCGG1290.0[m]DCCGG1300.0[m]DCCGG1310.0[m]DCCGG1320.0[m]DCCGG1330.0[m]DCCGG1340.0[m]DCCGG1350.0[m]DCCGG1360.0[m]DCCGG1370.0[m]DCCGG1380.0[m]DCCGG1390.0[m]DCCGG1410.0[m]DCCGG1420.0[m]DCCGG1430.0[m]DCCGG1440.0[m]DCCGG1460.0[m]DCCGG1470.0[m]DCCGG1480.0[m]DCCGG1500.0[m]DCCGG1510.0[m]DCCGG1520.0[m]DCCGG1530.0[m]DCCGG1540.0[m]DCCGG1560.0[m]DCCGG1570.0[m]DCCGG1580.0[m]DCCGG1590.0[m]DCCGG1600.0[m]DCCGG1612.0[m]DCCGG1618.0[m]DCCGG1624.0[m]DCCGG1630.0[m]DCCGG1636.0[m]DCCGG1642.0[m]DCCGG1648.0[m]DCCGG1654.0[m]DCCGG1660.0[m]DCCGG1662.0[m]DCCGG1672.0[m]DCCGG1684.0[m]DCCGG1690.0[m]DCCGG1702.0[m]DCCGG1705.0[m]DCCGG1711.0[m]DCCGG1717.0[m]DCCGG1722.7[m]CCGG1723.0[m]CCGG1725.8[m]CCGG1726.0[m]CCGG1727.0[m]CCGG1728.1[m]CCGG1729.0[m]CCGG1730.0[m]CCGG1731.4[m]CCGG1732.0[m]CCGG1733.7[m]CCGG1735.0[m]CCGG1735.5[m]CCGG1738.0[m]CCGG1738.3[m]CCGG1739.0[m]CCGG1741.0[m]CCGG1744.0[m]CCGG1747.0[m]CCGG1750.0[m]CCGG1753.0[m]CCGG1756.0[m]CCGG1759.0[m]CCGG1761.0[m]CCGG1765.0[m]CCGG1768.0[m]CCGG1771.0[m]CCGG1774.0[m]CCGG1777.0[m]CCGG1778.0[m]CCGG1779.0[m]CCGG1780.9[m]CCGG -
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 availableFMT0.000.00YESMDT0.000.00YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit15462969275775790091011001645164517081725174117611765177718271827 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.28 -
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]pdf87.99 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01727174014.4Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.04.0004.0004.00070Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.0413150.9000.680 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]MWD - GR RES DIR2281086MWD - GR RES DIR10761707 -
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 typeCONDUCTOR30227.036228.00.00LOTSURF.COND.13 3/81076.017 1/21091.00.00LOTOPEN HOLE1890.08 1/21890.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2281.03SPUD MUD8901.3231.0OIL (REGULAR)10001.06SPUD MUD10501.3232.0OIL (REGULAR)10911.4360.0LO-TOX OBM11501.3228.0LO-TOX OBM12441.3226.0LO-TOX OBM15181.3228.0LO-TOX OBM17511.3229.0LO-TOX OBM17861.3230.0LO-TOX OBM18901.3230.0OIL (REGULAR) -
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]pdf0.19