35/11-5
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General information
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Wellbore history
GeneralWell 35/11-5 was drilled on the "D" West prospect on the northwestern part of the Horda Platform, and ca 18 km north of the Troll Field. The primary objective for 35/11-5 was the Middle Jurassic Brent Group. Reservoirs were expected in the Tarbert, Ness, Etive, and Oseberg Formations. Secondary there was a possibility for reservoir development in the Late Jurassic Sognefjord Formation. Similar sands are the main reservoir in the Troll area, and were expected to be well developed in the eastern part of the block. No shallow gas warnings were given. Boulders might be encountered in the interval 395 - 532 m. The well was planned to be drilled to a total depth of 3678 m.Operations and resultsWildcat well 35/11-5 was spudded with the semi-submersible installation Sovereign Explorer on 27 June 1991 and drilled to TD at 3769 m in the Early Jurassic Statfjord Formation. The well reached a depth of 1118 m before technical problems caused the well to be plugged back and sidetracked. Further problems in the sidetrack caused the well to be abandoned and re-spudded on 18 July 1991, 50 m northwest of the original location. The first well bore was drilled with seawater and hi-vis pills. The second and final well bore was drilled with seawater and hi-vis pills to 1010 m, and with KCl/polymer mud from 1010 m to TDWater bearing sandstones were drilled in Palaeocene. The Draupne Formation was penetrated at 2657.5 m. The Sognefjord Formation came in at 2875 m and consisted predominantly of claystones with some sandstone interbeds. Shows were observed in cuttings, and RFT samples recovered contained oil and gas. However, reservoir quality of the sandstones was generally poor and there was less than 5 m of net pay. In the Middle Jurassic Brent Group, shows were observed in cores from 3208 m down to 3305 m. Light oil/condensate and gas was recovered from an RFT sample taken at 3214 m. Reservoir quality was however poor with only 5.4 m of net pay in the Tarbert Formation. Establishing the gas/-condensate-water contact was also difficult because of the poor porosity and permeability throughout the Brent Group. However, there were indications that hydrocarbons could be present below the base of the Tarbert Formation at 3216 m.Organic geochemistry show that the 217 m thick Draupne Formation contain mainly type II kerogen and has a rich potential for oil and gas. The deeper Heather Formation, with similar thickness, also has a rich potential for oil and gas but has a more variable source potential with kerogen type II to III. Various maturity indicators as well as weak shows recorded during drilling show that the Draupne shales are effectively immature for petroleum expulsion in the well position. Heather probably has reached sufficient thermal maturity to have generated and expelled some of its potential. Consistent with the shows record while drilling no migrant hydrocarbons were found by these analyses above base Cretaceous.A total of seven cores were cut in the interval 3215 m to 3356 m within the Brent Group, recovering a total of 124.6 m core. A total of 240 sidewall cores were attempted in 4 runs, and 150 were recovered. One RFT sample was taken at 2888.5 m in the Sognefjord Formation (gas, 5.7 litre 34.1° API oil, and mud filtrate) and two in the Tarbert Formation at 3213.5 m (gas, mud filtrate, and good trace of light oil), and at 3214 m (gas, mud filtrate and 1.3 litre 42.3° API oil)The well was permanently abandoned on 3 November 1991 as a minor oil and gas/condensate discovery.TestingNo drill stem test was performed. -
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]1020.003769.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13215.03236.8[m ]23239.03251.5[m ]33252.83267.8[m ]43269.03286.6[m ]53287.03299.6[m ]63304.03321.2[m ]73328.03355.9[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]124.6Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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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 typeCONDUCTOR30433.036435.00.00LOTINTERM.201001.0261003.01.51LOTINTERM.13 3/82679.017 1/22682.01.81LOTOPEN HOLE3769.012 1/43769.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CST GR10202661CST GR26903734CST GR27153676CST GR28752948DIL SDT AMS GR26793768DIL SDT LDT GR AMS9982683DLL MSFL AMS GR26793770FMS GR26793747LDT CNL AMS GR26793770MOBIL LSAL SWAL8932670MOBIL LSAL SWAL31743759MWD - GR RES DIR3833769RFT HP GR P28882946RFT HP GR P28893295RFT HP GR P32543255RFT HP GR P S32393373RFT HP GR S32130RFT HP GR S32140SHDT GR9982685VSP5503740 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit38277184585517011701175318361850188820232044255025502582262126582658287529503206320632163293331233423396339634673533357036283689 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.57 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf6.60 -
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]pdf111.74 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured3861.4820.032.0WATER BASED31.10.19913861.4820.032.0WATER BASED01.11.19913861.4820.032.0WATER BASED07.11.19913861.0020.032.0WATER BASED07.11.19913861.0020.032.0WATER BASED12.11.19913861.0020.032.0WATER BASED12.11.19913861.0020.032.0WATER BASED12.11.19913861.0020.032.0WATER BASED13.11.19913861.0020.032.0WATER BASED13.11.19913861.0020.032.0WATER BASED15.11.19913861.0020.032.0WATER BASED15.11.19913861.0020.032.0WATER BASED18.11.19913861.0020.032.0WATER BASED08.11.19913861.0020.032.0WATER BASED12.11.19914001.4820.032.0WATER BASED28.10.19914001.4820.032.0WATER BASED28.10.19914301.05WATER BASED28.06.19914451.05WATER BASED01.07.19914451.05WATER BASED01.07.19914461.05WATER BASED22.07.19914461.05WATER BASED22.07.19915471.05WATER BASED22.07.19915991.05WATER BASED01.07.19917061.05WATER BASED11.07.19917151.05WATER BASED03.07.19917951.05WATER BASED09.07.19917951.05WATER BASED10.07.19918451.05WATER BASED23.07.19918631.05WATER BASED24.07.199110101.3828.019.0WATER BASED25.07.199110101.3811.042.0WATER BASED29.07.199110101.3810.042.0WATER BASED29.07.199110101.3820.032.0WATER BASED29.07.199110101.3817.036.0WATER BASED30.07.199110101.388.021.0WATER BASED01.08.199110101.2019.021.0WATER BASED05.08.199110101.05WATER BASED25.07.199110101.388.021.0WATER BASED31.07.199110101.2019.021.0WATER BASED05.08.199110151.2021.025.0WATER BASED05.08.199110181.05WATER BASED15.07.199111101.05WATER BASED04.07.199111101.05WATER BASED04.07.199111101.05WATER BASED05.07.199111101.05WATER BASED08.07.199111101.05WATER BASED08.07.199111181.05WATER BASED16.07.199111181.05WATER BASED15.07.199111181.05WATER BASED15.07.199111181.05WATER BASED16.07.199111181.05WATER BASED18.07.199111181.05WATER BASED18.07.199111181.05WATER BASED19.07.199111431.2112.019.0WATER BASED06.08.199113061.2017.026.0WATER BASED07.08.199114811.2020.034.0WATER BASED08.08.199117321.2320.030.0WATER BASED09.08.199117921.2320.034.0WATER BASED12.08.199118871.2618.028.0WATER BASED12.08.199118871.2617.029.0WATER BASED12.08.199119611.2615.025.0WATER BASED12.08.199120431.2820.035.0WATER BASED13.08.199121161.2719.040.0WATER BASED13.08.199121321.2620.036.0WATER BASED15.08.199122421.2620.036.0WATER BASED15.08.199123871.2620.036.0WATER BASED16.08.199124171.2620.036.0WATER BASED20.08.199124611.3022.028.0WATER BASED20.08.199124861.3221.029.0WATER BASED20.08.199125021.3921.032.0WATER BASED20.08.199125371.3220.032.0WATER BASED22.08.199126161.3120.032.0WATER BASED22.08.199126861.2820.032.0WATER BASED23.08.199126861.3120.032.0WATER BASED26.08.199126861.3120.032.0WATER BASED26.08.199126861.3120.032.0WATER BASED27.08.199126861.3120.032.0WATER BASED30.08.199126861.3120.032.0WATER BASED02.09.199126861.3120.032.0WATER BASED02.09.199126861.3120.032.0WATER BASED02.09.199126861.3120.032.0WATER BASED26.08.199126861.3120.032.0WATER BASED28.08.199127151.3220.032.0WATER BASED03.09.199128321.4420.032.0WATER BASED04.09.199128691.4420.032.0WATER BASED05.09.199128741.4420.032.0WATER BASED06.09.199129351.4420.032.0WATER BASED09.09.199129611.4420.032.0WATER BASED09.09.199130001.4420.032.0WATER BASED09.09.199130311.4420.032.0WATER BASED10.09.199130351.4420.032.0WATER BASED11.09.199130501.4420.032.0WATER BASED12.09.199131361.4420.032.0WATER BASED16.09.199132091.4420.032.0WATER BASED16.09.199132151.4420.032.0WATER BASED16.09.199132151.5120.032.0WATER BASED16.09.199132281.5120.032.0WATER BASED17.09.199132421.5120.032.0WATER BASED18.09.199132441.5120.032.0WATER BASED19.09.199132531.5120.032.0WATER BASED20.09.199132541.5120.032.0WATER BASED23.09.199132691.5120.032.0WATER BASED23.09.199132691.5120.032.0WATER BASED23.09.199132861.5120.032.0WATER BASED25.09.199132871.5120.032.0WATER BASED25.09.199132931.5120.032.0WATER BASED27.09.199133041.5120.032.0WATER BASED27.09.199133051.5120.032.0WATER BASED30.09.199133281.5120.032.0WATER BASED30.09.199133391.5120.032.0WATER BASED30.09.199133561.5120.032.0WATER BASED01.10.199133661.5120.032.0WATER BASED02.10.199134541.5120.032.0WATER BASED07.10.199135661.5120.032.0WATER BASED07.10.199136221.5120.032.0WATER BASED08.10.199136911.5120.032.0WATER BASED10.10.199137691.5120.032.0WATER BASED11.10.199137691.5120.032.0WATER BASED15.10.199137691.5120.032.0WATER BASED11.10.199137691.5120.032.0WATER BASED15.10.199137691.5120.032.0WATER BASED15.10.199137691.5120.032.0WATER BASED15.10.199137691.5120.032.0WATER BASED17.10.199137691.5120.032.0WATER BASED17.10.199137691.5120.032.0WATER BASED18.10.199137691.5120.032.0WATER BASED21.10.199137691.5120.032.0WATER BASED21.10.199137691.5120.032.0WATER BASED21.10.199137691.4820.032.0WATER BASED23.10.199137691.4820.032.0WATER BASED25.10.199137691.4820.032.0WATER BASED28.10.1991 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1020.0[m]SWCMOBIL1030.0[m]DCMOBIL1040.0[m]SWCMOBIL1062.0[m]SWCMOBIL1089.0[m]SWCMOBIL1110.0[m]DCMOBIL1130.0[m]DCMOBIL1150.0[m]SWCMOBIL1180.0[m]SWCMOBIL1200.0[m]DCMOBIL1223.0[m]SWCMOBIL1240.0[m]DCMOBIL1260.0[m]DC1261.0[m]SWCMOBIL1280.0[m]DCMOBIL1295.0[m]SWCMOBIL1310.0[m]DCMOBIL1332.0[m]SWCMOBIL1350.0[m]DCMOBIL1370.0[m]SWCMOBIL1380.0[m]DCMOBIL1390.0[m]DCMOBIL1411.0[m]SWCMOBIL1430.0[m]DCMOBIL1440.0[m]DCMOBIL1449.0[m]SWCMOBIL1460.0[m]DCMOBIL1460.0[m]DC1485.0[m]SWCMOBIL1500.0[m]DCMOBIL1520.0[m]SWCMOBIL1540.0[m]DCMOBIL1560.0[m]SWCMOBIL1580.0[m]DCMOBIL1600.0[m]DCMOBIL1626.0[m]SWCMOBIL1640.0[m]DCMOBIL1650.0[m]DCMOBIL1660.0[m]SWCMOBIL1670.0[m]DCMOBIL1680.0[m]DCMOBIL1696.0[m]SWCMOBIL1700.0[m]DCMOBIL1709.0[m]SWCMOBIL1710.0[m]SWCMOBIL1730.0[m]DCMOBIL1749.0[m]SWCMOBIL1755.0[m]SWCMOBIL1770.0[m]SWCMOBIL1790.0[m]DCMOBIL1797.0[m]SWCMOBIL1810.0[m]DCMOBIL1870.0[m]DCMOBIL1910.0[m]DCMOBIL1930.0[m]DCMOBIL1940.0[m]DCMOBIL1950.0[m]DCMOBIL1980.0[m]DCMOBIL1990.0[m]DCMOBIL2000.0[m]DCMOBIL2020.0[m]DCMOBIL2040.0[m]DCMOBIL2384.0[m]SWCMOBIL2421.0[m]SWCMOBIL2449.0[m]SWCMOBIL2460.0[m]DC2480.0[m]SWCMOBIL2515.0[m]SWCMOBIL2546.0[m]SWCMOBIL2582.0[m]DCMOBIL2625.0[m]SWCMOBIL2665.0[m]DCMOBIL2671.0[m]DC2686.0[m]DCMOBIL2706.0[m]SWCMOBIL2715.0[m]SWCMOBIL2723.0[m]SWCMOBIL2731.0[m]DCMOBIL2740.0[m]SWCMOBIL2748.0[m]SWCMOBIL2759.0[m]SWCMOBIL2770.0[m]DCMOBIL2774.0[m]SWCMOBIL2790.0[m]SWCMOBIL2797.0[m]DC2797.0[m]DC2800.0[m]DCMOBIL2809.0[m]SWCMOBIL2818.0[m]DCMOBIL2830.0[m]SWCMOBIL2842.0[m]DCMOBIL2850.0[m]SWCMOBIL2859.0[m]SWCMOBIL2859.0[m]DCMOBIL2869.0[m]DC2870.0[m]SWCMOBIL2875.0[m]SWCMOBIL2886.0[m]SWCMOBIL2889.0[m]SWCMOBIL2893.0[m]SWCMOBIL2900.0[m]SWCMOBIL2905.0[m]DC2906.0[m]SWCMOBIL2917.0[m]SWCMOBIL2930.0[m]SWCMOBIL2941.0[m]DCMOBIL2951.0[m]SWCMOBIL2959.0[m]DC2962.0[m]DCMOBIL2969.0[m]SWCMOBIL2988.0[m]SWCMOBIL2995.0[m]DC3001.0[m]DCMOBIL3013.0[m]SWCMOBIL3031.0[m]DCMOBIL3043.0[m]SWCMOBIL3049.0[m]DC3052.0[m]DCMOBIL3060.0[m]SWCMOBIL3070.0[m]DCMOBIL3091.0[m]DCMOBIL3097.0[m]SWCMOBIL3103.0[m]DC3109.0[m]DCMOBIL3114.0[m]SWCMOBIL3139.0[m]DCMOBIL3151.0[m]DCMOBIL3161.0[m]SWCMOBIL3178.0[m]SWCMOBIL3194.0[m]SWCMOBIL3202.0[m]DC3221.0[m]DC3247.0[m]DC3343.0[m]DC3396.0[m]SWCMOBIL3418.0[m]SWCMOBIL3418.0[m]DC3430.0[m]DCMOBIL3481.0[m]DCMOBIL3483.0[m]SWCMOBIL3499.0[m]DCMOBIL3520.0[m]SWCMOBIL3558.0[m]SWCMOBIL3567.0[m]SWCMOBIL3588.0[m]SWCMOBIL3601.0[m]DCMOBIL3609.0[m]SWCMOBIL3629.0[m]SWCMOBIL3649.0[m]SWCMOBIL3649.0[m]DC3670.0[m]DCMOBIL3748.0[m]DCMOBIL3769.0[m]DCMOBIL