25/8-11
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General information
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Wellbore history
GeneralThe 25/8-11 well was drilled in PL 027 with Esso as the operator and sole licensee. The well was drilled in the Ringhorn prospect, which is located approximately 14 km North of Balder. The primary target was the Paleocene Hermod Formation sandstones. Jurassic sandstones constituted a secondary target.Operations and resultsWildcat well 25/8-11 was spudded with the semi-submersible drilling rig "West Alpha" on 16 October 1997 and drilled to a total depth of 1994 m in Early Jurassic sediments of the Statfjord Formation. The well was drilled with spud mud down to 1001 m and oil-based mud from 1001 m to TD. Hydrocarbons were encountered in both targets. Top Hermod sandstones were found at 1765 m. The Paleocene OWC (from wire line log) was found at 1775 m. The Paleocene reservoir properties were close to those of the Balder reservoirs and it was not the plan to test this reservoir. The top of the Jurassic reservoir (Top Statfjord Formation) came in at 1891 m. The Jurassic OWC (from wire line log) was found at 1935 m. The discovery in the Jurassic was the first of it's kind in this area and it was therefore decided to test this part of the Ringhorn Discovery. One core was cut in the interval 1763 m to 1790 m from lowermost Sele Formation and through half of the Hermod Formation. Two MDT samples were taken in the Statfjord Formation: one oil sample from 1919 m and one water sample from 1938 m. After production testing the well was suspended as an oil discovery on 2 December 1997.TestingA DST was performed in the interval 1892.5 m to 1909.5 m in thin sands of the Upper Statfjord Formation. The well produced 517 Sm3 oil per day and with a GOR of 42 Sm3/Sm3 on a 40/64th inch choke. Only surface samples were collected. Initial reservoir conditions at 1882 m were found to be 18.74 Mpa and 78 deg C. The plan was to continue with the test by perforating a lower sand interval and do a commingled test of both sand intervals. Due to bad weather this was delayed and when the weather improved technical problems lead to suspension of the test without any data obtained from the lower interval. -
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]1030.001994.50 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11763.01789.7[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]26.7Cores 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 typeLaboratory1030.0[m]DCCGG1060.0[m]DCCGG1120.0[m]DCCGG1140.0[m]DCCGG1150.0[m]DCCGG1180.0[m]DCCGG1220.0[m]DCCGG1260.0[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]DCCGG1460.0[m]DCCGG1580.0[m]DCCGG1670.0[m]DCCGG1680.0[m]DCCGG1745.0[m]DCCGG1750.0[m]DCCGG1770.6[m]CCGG1773.3[m]CCGG1778.2[m]CCGG1786.0[m]CCGG1810.0[m]DCCGG1820.0[m]DCCGG1830.0[m]DCCGG1850.0[m]DCCGG1870.0[m]DCCGG1900.0[m]DCRRI1920.0[m]DCRRI1970.0[m]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 availableDSTDST 11910.001893.0015.11.1997 - 00:00YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit14655565170870886194397811291138167816781743176517681774179618241872187618761891 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.32 -
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]pdf49.47 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01893191016.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.078Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.05202300044 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]AIT UBI DSI9921986CMR IPL16711990LDL CNL GR15781995MDT17661981MWD - DIR920998MWD - GR RES DIR2191001MWD - GR RES DIR10241994SWC16781985VSP3501990 -
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 typeCONDUCTOR30220.036221.00.00LOTINTERM.13 3/8998.017 1/21008.00.00LOTOPEN HOLE1994.08 1/21994.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured10011.3224.0OIL BASED10241.3226.0OIL BASED14711.3220.0OIL BASED15651.3225.0OIL BASED17901.3326.0OIL BASED19941.13DUMMY19941.3226.0OIL 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]pdf0.19