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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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 -
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 -
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 -
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 -
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) -
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