35/11-8 S
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General information
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Wellbore history
GeneralWell 35/11-8 S is located ca 15 km due north of the Troll Field. It was designed to test the hydrocarbon potential in the H-structure located in a down-faulted position west of the F/C complex where oil and gas was discovered in the wells 35/11-4 and -7. The main targets were the Brent Group and the Sognefjord Formation equivalent. Possible secondary targets were seen in Intra Draupne sandstone and a mound feature in the Paleocene sequence.Operations and resultsWildcat well 35/11-8 S was spudded with the semi-submersible installation Treasure Saga on 3 March 1996 and drilled to TD at 3624 m (3355 m TVD RKB) m in the Early Jurassic Drake Formation. The well was drilled vertically in the top hole, starting to build angle below the 30" casing shoe at 447 m. From 950 m to 2250 m the deviation was kept at 31 ± 2°, from which point the inclination was gradually reduced towards a more vertical path. After the testing phase, operations were interrupted for some three days by an industrial strike. Operations went without significant technical problems. The well was drilled with spud mud down to 1233 m and with KCl/polymer mud from 1233 m to TD.The Paleocene mound feature proved to consists of 66 m of water bearing sand with weak shows in the uppermost part.The prognosed lead related to the high amplitude Intra Draupne reflector corresponded to the Late Jurassic source rock. A thin sandstone at the base of the Sognefjord Formation was water filled with weak shows. Oil and gas was discovered in a 115 m thick Late Jurassic turbiditic sandstone unit at 2860 m. The sequence could not be correlated with the Sognefjord Formation in the neighbouring wells and is classified as an Intra Heather Sandstone unit. From 2860 to 2881 m 20.7 m net pay gas reservoir showed a gas saturation of 89 % and the average porosity was calculated to 21.9 %. A 40.1 m net pay oil zone was calculated for the interval between 2881m and 2938 m. Average porosity for this interval is 22.1 % and the oil saturation is 80.0 %. MDT pressure measurements gave a gas-oil contact at 2881 m (2600 m TVD MSL) and an oil-water contact at 2938 m (2654 m TVD MSL). Low saturation of residual hydrocarbons were observed in intervals below the oil-water contact. The Brent Group was encountered at 3376.5 m and was water bearing. A trace oil show was however recorded at 3467 m in the Etive Formation. The MDT pressure measurements failed to define a water gradient due to poor reservoir quality. Four cores were taken in the Intra Heather Sandstone unit, covering the gas zone, the oil zone, and parts of the water zone. An MDT water sample was taken at 2818 m in the Sognefjord Formation. MDT water samples were taken also in the Brent Group.The well was permanently abandoned on 11 May 1996 as an oil and gas discovery.TestingThree drill stem tests were conducted in the Intra Heather Sandstone unit. DST 1 tested the interval 2924 m to 2931 m, DST 1B tested the intervals 2924 m to 2931 m and 2910 m to 2920 m, and DST 2 tested the interval 2885 m to 2892 m. All three tests produced 0.85 g/cm3 (35 deg API) oil with GOR in the range 95 to 113 Sm3/Sm3. -
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]1240.003625.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12866.02883.7[m ]22884.02911.5[m ]32911.52936.2[m ]42938.02964.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]95.9Cores 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 availableDSTTEST 1B2931.002885.0021.04.1996 - 00:00YESDSTTEST22892.002885.0027.04.1996 - 13:47YES -
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 typeCONDUCTOR30447.036450.00.00LOTSURF.COND.13 3/81220.017 1/21233.00.00LOTINTERM.9 5/83232.012 1/43242.00.00LOTOPEN HOLE3624.08 1/23624.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.02924293119.12.02910292019.13.02886290112.7Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.026.00021.00027.0001042.026.00024.00027.0001053.026.00025.00027.000103Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.0700790000.8500.7201122.0860820000.8500.690953.0520580000.8500.706112 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VBDL USIT GR CCL AMS16503227CST GR17853135CST GR25883462DLL MSFL LSS LDL CNL GR AMS SP11953629FMS NGT17033110MDT GR18722975MDT GR28962930MDT GR33803483MDT GR33813490MWD3873624VSP GR14203600 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit3877227851618161816811730179718771975202120412063208721242124229225982678267826862686278928072825286033773377338734593480350535763576 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.58 -
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]pdf18.64 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4491.03WATER BASED12331.3016.0WATER BASED17871.3024.0WATER BASED22241.3028.0WATER BASED26501.12WATER BASED29071.1214.0WATER BASED30851.1216.0WATER BASED32421.3023.0WATER BASED32631.3122.0WATER BASED36241.3122.0WATER BASED -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1240.0[m]DCRRI1260.0[m]DCRRI1280.0[m]DCRRI1300.0[m]DCRRI1320.0[m]DCRRI1340.0[m]DCRRI1360.0[m]DCRRI1380.0[m]DCRRI1400.0[m]DCRRI1420.0[m]DCRRI1440.0[m]DCRRI1460.0[m]DCRRI1480.0[m]DCRRI1500.0[m]DCRRI1520.0[m]DCRRI1540.0[m]DCRRI1560.0[m]DCRRI1580.0[m]DCRRI1600.0[m]DCRRI1620.0[m]DCRRI1640.0[m]DCRRI1650.0[m]DCRRI1660.0[m]DCRRI1670.0[m]DCRRI1680.0[m]DCRRI1690.0[m]DCRRI1700.0[m]DCRRI1710.0[m]DCRRI1720.0[m]DCRRI1730.0[m]DCRRI1740.0[m]DCRRI1750.0[m]DCRRI1760.0[m]DCRRI1770.0[m]DCRRI1785.0[m]SWCRRI1792.0[m]SWCRRI1800.0[m]DCRRI1810.0[m]DCRRI1820.0[m]DCRRI1826.0[m]SWCRRI1840.0[m]DCRRI1850.0[m]DCRRI1860.0[m]DCRRI1880.0[m]DCRRI1888.0[m]SWCRRI1905.0[m]SWCRRI1920.0[m]DCRRI1930.0[m]DCRRI1940.0[m]DCRRI1950.0[m]DCRRI1960.0[m]DCRRI1970.0[m]DCRRI1980.0[m]DCRRI1990.0[m]DCRRI2000.0[m]DCRRI2010.0[m]DCRRI2020.0[m]DCRRI2030.0[m]DCRRI2040.0[m]DCRRI2050.0[m]SWCRRI2060.0[m]DCRRI2070.0[m]DCRRI2080.0[m]DCRRI2089.0[m]SWCRRI2101.0[m]DCRRI2110.0[m]DCRRI2120.0[m]DCRRI2130.0[m]DCRRI2150.0[m]DCRRI2190.0[m]DCRRI2210.0[m]DCRRI2230.0[m]DCRRI2250.0[m]DCRRI2270.0[m]DCRRI2290.0[m]DCRRI2310.0[m]DCRRI2330.0[m]DCRRI2350.0[m]DCRRI2370.0[m]DCRRI2390.0[m]DCRRI2410.0[m]DCRRI2430.0[m]DCRRI2450.0[m]DCRRI2470.0[m]DCRRI2510.0[m]DCRRI2530.0[m]DCRRI2550.0[m]DCRRI2570.0[m]DCRRI2580.0[m]DCRRI2590.0[m]DCRRI2600.0[m]DCRRI2610.0[m]DCRRI2620.0[m]DCRRI2630.0[m]DCRRI2640.0[m]DCRRI2650.0[m]DCRRI2660.0[m]SWCRRI2670.0[m]SWCRRI2680.0[m]DCRRI2690.0[m]DCRRI2700.0[m]DCRRI2710.0[m]DCRRI2720.0[m]DCRRI2730.0[m]DCRRI2740.0[m]DCRRI2754.0[m]SWCRRI2760.0[m]DCRRI2770.0[m]DCRRI2780.0[m]DCRRI2787.0[m]SWCRRI2800.0[m]DCRRI2810.0[m]DCRRI2820.0[m]DCRRI2830.0[m]DCRRI2840.0[m]DCRRI2852.0[m]DCRRI2862.0[m]DCRRI2872.0[m]DCRRI2878.0[m]CRRI2880.0[m]CRRI2894.0[m]CRRI2899.0[m]CRRI2904.0[m]DCRRI2907.0[m]CRRI2918.0[m]CRRI2930.0[m]CRRI2933.0[m]CRRI2935.0[m]CRRI2950.0[m]CRRI2962.0[m]CRRI2970.0[m]DCRRI2980.0[m]DCRRI2990.0[m]SWCRRI2997.0[m]SWCRRI3010.0[m]DCRRI3020.0[m]DCRRI3030.0[m]DCRRI3038.0[m]SWCSWC3050.0[m]DCRRI3060.0[m]DCRRI3070.0[m]DCRRI3080.0[m]DCRRI3090.0[m]DCRRI3100.0[m]DCRRI3110.0[m]DCRRI3120.0[m]DCRRI3130.0[m]DCRRI3135.0[m]SWCRRI3140.0[m]DCRRI3150.0[m]DCRRI3160.0[m]DCRRI3170.0[m]DCRRI3180.0[m]DCRRI3190.0[m]DCRRI3200.0[m]DCRRI3210.0[m]DCRRI3222.0[m]DCRRI3250.0[m]DCRRI3260.0[m]DCRRI3270.0[m]DCRRI3280.0[m]DCRRI3290.0[m]DCRRI3300.0[m]DCRRI3310.0[m]DCRRI3320.0[m]DCRRI3330.0[m]DCRRI3340.0[m]DCRRI3350.0[m]DCRRI3360.0[m]DCRRI3370.0[m]DCRRI3380.0[m]DCRRI3390.0[m]DCRRI3400.0[m]DCRRI3410.0[m]DCRRI3420.0[m]DCRRI3430.0[m]DCRRI3440.0[m]DCRRI3450.0[m]DCRRI3460.0[m]DCRRI3470.0[m]DCRRI3480.0[m]DCRRI3503.0[m]SWCRRI3510.0[m]DCRRI3520.0[m]DCRRI3535.0[m]DCRRI3545.0[m]SWCRRI3555.0[m]DCRRI3565.0[m]DCRRI3575.0[m]DCRRI3595.0[m]DCRRI3605.0[m]DCRRI