25/11-25 A
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General information
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Wellbore history
GeneralWell 25/11-5 S and the geological sidetrack 25/11-25 A are located in a petroleum system just south of the Balder Field and southwest of the Grane Field, on the western margin of the Utsira High. The primary objective of the wells was to prove commercial hydrocarbons in the two independent prospects; M-prospect and Jacob North prospect (1500m apart). In 25/11-25 S the primary objective was to confirm producible oil from Intra Balder Formation Sandstone ("Odin sands"). A secondary objective was to evaluate the shallower Frigg sand and the Hermod Formation sandstones.The objective of the 25/11-25 A sidetrack was to evaluate the formations within the Jurassic Statfjord Formation. The discovery of a 4 meter oil column in the Statfjord Formation in the recently drilled Jakob Sør prospect by well 25/11-24necessitated an evaluation of potential Statfjord Formation targets in the area. The Jakob Nord and Jakob Sør prospects were separated by a saddle point coinciding with the oil water contact encountered in well 25/11-24.Operations and resultsWildcat well 25/11-25 S was spudded with the semi-submersible installation Transocean Winner on 20 January 2008 and drilled to TD at 2142 m in the Paleocene Lista Formation. No shallow gas was observed by the ROV at the wellhead or by the MWD while drilling the 36" hole and the 12 1/4" pilot hole. The well was drilled with seawater down to 1094 m, and with Glydril mud (with ca 4% glycol) from 1094 m to TD.The well penetrated rocks of Quaternary and Tertiary age. No Frigg sand was encountered and no recordable sand volumes were present in the Sele Formation. The well penetrated the Odin reservoir section at 2045 m, 14.4 m deeper than prognosed. Wire line logs confirmed an oil bearing interval between 2045 m and 2082.5 m proving oil down to the OWC at 2082.5 m (1790m TVD RKB). No shows were observed in the well other than in the oil-bearing Intra Balder Formation sandstone.The well track was plugged back to 1476 m and permanently abandoned on 15 February 2008 as an oil discovery.Well 25/11-25 A was sidetracked from 25/11-25 S at 1023 m and drilled to a total depth of 2448 m (2058 m TVD RKB). The well was drilled with Glydril mud (with ca 4% glycol) from kick-off to TD.The well penetrated rocks of Tertiary, Cretaceous and Jurassic age. TD of the well was set in sandstones and claystones of the Statfjord Formation. The Statfjord Formation in well 25/11-25 A was encountered at 2372 m, 12 m TVD deeper than prognosed. The reservoir was more poorly developed than expected and there were no indications of hydrocarbons. Biostratigraphic results indicated presence of the lowermost part of the Lower Statfjord Formation only. No shows were reported in well 25/11-25 A.One core was cut in 25/11-25 S in a hydrocarbon bearing interval from 2045 m - 2063 m the Intra Balder Formation sandstone, with 93% recovery. No cores were cut in 25/11-25 A. MDT oil sampling was performed at 2046 m and at 2065 m in 25/11-25 S. In total 175.7 litres were pumped during the sampling run of which 94.9 litres were pumped to the well bore. No fluid sampling was done in 25/11-25 A.Sidetrack well 25/11-25 A was permanently abandoned on 10 March 2008 as dry well.TestingNo drill stem test was performed in the wells. -
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]1040.002440.00 -
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 typeLINER9 5/81913.012 1/41921.01.70LOTOPEN HOLE2448.08 1/22448.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]DSI HRLA TLD MCFL 044PUP18772453MDT GR24262676MWD - DIR151208MWD - EWR P4 DGR PCDC PWD10232448MWD - EWR P4 DGR PWD8061094MWD - EWR P4D DGR PWD208806MWD - EWR P4D DGR PWR208840 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1516667468148149541097110312461334163716651957195720632074216721822190223022612269226923002310236223622372 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured10251.2724.0Glydril11141.2624.0Glydril11971.3026.0Glydril13381.3929.0Glydril14201.4029.0Glydril16181.4526.0Glydril16871.4529.0Glydril17131.2614.0Glydril19211.4530.0Glydril20131.2620.0Glydril24481.2629.0Glydril -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1150.0[m]DCFUGRO1170.0[m]DCFUGRO1190.0[m]DCFUGRO1210.0[m]DCFUGRO1230.0[m]DCFUGRO1250.0[m]DCFUGRO1270.0[m]DCFUGRO1290.0[m]DCFUGRO1310.0[m]DCFUGRO1330.0[m]DCFUGRO1350.0[m]DCFUGRO1370.0[m]DCFUGRO1390.0[m]DCFUGRO1410.0[m]DCFUGRO1430.0[m]DCFUGRO1450.0[m]DCFUGRO1470.0[m]DCFUGRO1490.0[m]DCFUGRO1510.0[m]DCFUGRO1530.0[m]DCFUGRO1550.0[m]DCFUGRO1570.0[m]DCFUGRO1590.0[m]DCFUGRO1610.0[m]DCFUGRO1630.0[m]DCFUGRO1650.0[m]DCFUGRO1670.0[m]DCFUGRO1690.0[m]DCFUGRO1710.0[m]DCFUGRO1730.0[m]DCFUGRO1750.0[m]DCFUGRO1770.0[m]DCFUGRO1790.0[m]DCFUGRO1810.0[m]DCFUGRO1830.0[m]DCFUGRO1850.0[m]DCFUGRO1870.0[m]DCFUGRO1890.0[m]DCFUGRO1910.0[m]DCFUGRO1932.0[m]DCFUGRO1953.0[m]DCFUGRO1962.0[m]DCFUGRO1974.0[m]DCFUGRO1989.0[m]DCFUGRO1992.0[m]DCFUGRO2004.0[m]DCFUGRO2016.0[m]DCFUGRO2028.0[m]DCFUGRO2040.0[m]DCFUGRO2052.0[m]DCFUGRO2064.0[m]DCFUGRO2076.0[m]DCFUGRO2088.0[m]DCFUGRO2094.0[m]DCFUGRO2109.0[m]DCFUGRO2121.0[m]DCFUGRO2133.0[m]DCFUGRO2148.0[m]DCFUGRO2160.0[m]DCFUGRO2172.0[m]DCFUGRO2184.0[m]DCFUGRO2202.0[m]DCFUGRO2220.0[m]DCFUGRO2232.0[m]DCFUGRO2241.0[m]DCFUGRO2256.0[m]DCFUGRO2271.0[m]DCFUGRO2283.0[m]DCFUGRO2298.0[m]DCFUGRO2310.0[m]DCFUGRO2322.0[m]DCFUGRO2328.0[m]DCFUGRO2334.0[m]DCFUGRO2340.0[m]DCFUGRO2347.0[m]DCFUGRO2350.0[m]DCFUGRO2351.0[m]DCFUGRO2353.0[m]DCFUGRO2356.0[m]DCFUGRO2359.0[m]DCFUGRO2362.0[m]DCFUGRO2365.0[m]DCFUGRO2365.0[m]DCFUGRO2371.0[m]DCFUGRO2374.0[m]DCFUGRO2377.0[m]DCFUGRO2380.0[m]DCFUGRO2389.0[m]DCFUGRO2395.0[m]DCFUGRO2401.0[m]DCFUGRO2407.0[m]DCFUGRO2416.0[m]DCFUGRO2422.0[m]DCFUGRO2428.0[m]DCFUGRO2434.0[m]DCFUGRO2440.0[m]DCFUGRO2446.0[m]DCFUGRO2448.0[m]DCFUGRO