25/5-1
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General information
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Wellbore history
GeneralWell 25/5-1 was drilled on a Jurassic structure straddling the two blocks 25/5 and 25/2. It is located near the crest of a westward tilted Jurassic fault block in the northern part of block 25/5. The northern extension of this structure was drilled in 1977 by well 25/2-6 which is located In the southern part of the neighbouring block 25/2, in a down dip position relative to well 25/5-1. Well 25/2-6 was plugged and abandoned with limited oil shows in sandstones of the Early Jurassic Statfjord Formation. The main objectives of well 25/5-1 were to test the hydrocarbon potential of the middle Jurassic Vestland Group sandstones and the Early Jurassic Statfjord Formation sandstones up dip of well 25/2-6.Operations and resultsWildcat well 25/5-1 was spudded 12 May 1987 by Norcem semi-submersible rig Nortrym and completed 1 August 1987 at a depth of 3430 m in the Triassic Group. Drilling proceeded without significant problems. There was no sign of shallow gas. One core was cut in the Draupne Formation between 2916 and 2925 m. Top reservoir (Hugin Formation) was encountered at 2984 m. Five cores were cut between 2990 - 3081 m in the Hugin and Sleipner formations and into the Drake Formation. The logs showed that the whole reservoir section contained oil down to base Sleipner / top Drake Formation, which formed a lithological sand / shale contact at 3060 m. RFT pressure measurements indicated an oil/water contact at ca 65 m below this level, implying a vertical oil column of 166 m. Due to this the hole was decided to be sidetracked to find the oil/water contact in the Sleipner Formation. Top Statfjord came in at 3232 m, and 3 cores were cut in the interval 3235 - 3291 m. There were shows down to 3264 m; below this depth the sandstones were water bearing. The Triassic was also water bearing. RFT fluid samples were taken at 3025 m and 2989.5 m. Both samples contained oil and mud filtrate.The well was plugged and abandoned on 1 August 1987 as an oil discovery.TestingThree DSTs were performed, two of them with re-runs due to technical problems.Three DSTs were performed, two of them with re-runs due to technical problems.DST 1 tested the interval 3233 to 3254 m in the Statfjord Group. This test did not produce formation flow to surface, but a bottom hole sample was taken, containing mud filtrate and water.DST 2A and 2B tested the interval 3025 to 3045 m in the Middle Sleipner Formation. DST 2A did not obtain reliable data due to technical problems. Bottom hole samples were taken. The re-run DST 2B produced 437 Sm3 oil/day through a 32/64 choke. The GOR was 201 m3/m3 and the oil density was 0.8373 g/cm3.DST 3A and 3B tested the interval 2987 to 3002 m in the Upper Sleipner Formation. DST 3A had technical problems and only the clean-up flow and the first build-up gave valid data. Maximum temperature measured at 2986.4 m was 106.4 C. The re-run DST 3B produced 442 Sm3/oil/day through a 32/64 choke. The GOR was 186 Sm3/Sm3 and the oil density was 0.825 g/cm3. -
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]620.003430.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom22990.03007.8[m ]33008.53027.3[m ]43027.53046.2[m ]53046.23063.5[m ]63064.03080.4[m ]73235.13253.0[m ]83253.53272.0[m ]93272.63291.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]143.9Cores 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 availableDST0.000.00YESDSTDST33002.002987.00YESDSTDST3B3254.003233.0031.07.1987 - 00:00YES -
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 typeCONDUCTOR30203.036612.00.00LOTSURF.COND.20600.026815.01.14LOTINTERM.13 3/81978.017 1/22218.01.66LOTINTERM.9 5/82910.512 1/42941.01.86LOTLINER73429.08 1/23429.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.03233325412.72.03045302512.72.13045302512.73.03002298712.73.12987300212.7Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.02.08.0002.130.00011.00030.0003.010.0003.132.000Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.02.0396710000.8270.7051782.1437880000.8370.7052013.0339740000.8250.7902173.1442820000.8250.815186 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BGT5981972CBL VDL3102910CST GR20863410DIL LSS GR5983427DLL MSFL GR29103425LDT CNL EPT NGT29103429LDT CNL GR29103149LDT GR5982916MWD2193426RFT GR02989RFT GR29853058RFT GR32343399SHDT GR19773429VSP11003425 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit14344492095111021287134521692169220022142240227524002570258825882802290029052905295529842984299630603060312932323374 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.51 -
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]pdf26.28 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured11871.0930.07.8WATER BASED21.05.198713581.1028.05.8WATER BASED21.05.198718571.1332.08.8WATER BASED25.05.198719961.1524.06.8WATER BASED25.05.198722181.1318.04.9WATER BASED29.05.198722391.1319.04.9WATER BASED02.06.198724971.1418.04.4WATER BASED02.06.198725811.14182.05.8WATER BASED02.06.198726411.1419.04.9WATER BASED03.06.198727291.1419.05.8WATER BASED04.06.198727461.1419.04.9WATER BASED09.06.198728831.1423.06.8WATER BASED09.06.198729161.1426.06.8WATER BASED09.06.198729251.1526.06.8WATER BASED09.06.198729411.2128.05.3WATER BASED15.06.198729671.2235.07.3WATER BASED16.06.198729941.2234.05.3WATER BASED16.06.198730791.2231.05.8WATER BASED22.06.198731421.2228.05.8WATER BASED22.06.198731471.2228.05.8WATER BASED22.06.198731621.2226.05.8WATER BASED22.06.198732351.2427.05.8WATER BASED23.06.198732541.2431.05.8WATER BASED24.06.198732911.2431.05.8WATER BASED25.06.198733331.2429.05.8WATER BASED26.06.198734301.2432.05.8WATER BASED29.06.1987 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory2922.4[m]CAPT2923.8[m]CAPT2950.0[m]DC2972.0[m]DC2980.0[m]DC2982.0[m]DC2983.0[m]DC2987.0[m]DC2990.3[m]C2990.3[m]COD2990.8[m]CAPT2991.4[m]CAPT2992.3[m]C2992.3[m]CAPT2992.3[m]COD2992.8[m]CAPT2992.8[m]COD2993.7[m]COD2994.2[m]CAPT2994.5[m]CAPT2994.5[m]COD2994.5[m]C2994.8[m]CAPT2995.0[m]DC2996.0[m]COD2996.3[m]C2996.9[m]CAPT2997.3[m]C2998.2[m]COD2998.3[m]C2998.7[m]CAPT2998.8[m]CAPT2998.9[m]CAPT2999.0[m]COD2999.3[m]C3000.0[m]CAPT3000.5[m]C3000.5[m]COD3001.7[m]CAPT3002.5[m]C3003.5[m]COD3004.5[m]C3004.8[m]CAPT3005.0[m]CAPT3005.5[m]C3005.5[m]CAPT3006.5[m]COD3006.5[m]C3006.6[m]CAPT3007.8[m]CAPT3008.5[m]CAPT3008.7[m]COD3008.8[m]CAPT3008.8[m]C3009.1[m]CAPT3009.2[m]CAPT3009.7[m]COD3009.8[m]C3010.5[m]C3011.5[m]C3012.3[m]COD3013.5[m]C3015.4[m]C3016.4[m]COD3016.5[m]COD3017.5[m]C3019.5[m]C3020.4[m]COD3021.5[m]C3023.5[m]C3025.5[m]C3025.7[m]COD3027.0[m]C3028.5[m]C3030.5[m]C3031.5[m]COD3032.5[m]C3034.7[m]COD3034.8[m]C3034.8[m]CAPT3035.5[m]C3037.5[m]C3038.2[m]CAPT3038.4[m]CAPT3038.5[m]COD3039.5[m]C3040.5[m]CAPT3041.5[m]C3042.3[m]CAPT3042.8[m]CAPT3042.8[m]COD3043.1[m]COD3043.3[m]CAPT3044.0[m]C3044.7[m]CAPT3044.8[m]C3044.8[m]CAPT3045.4[m]CAPT3045.5[m]COD3046.5[m]CAPT3046.5[m]CAPT3046.7[m]CAPT3046.9[m]CAPT3047.8[m]C3048.2[m]CAPT3048.8[m]CAPT3048.8[m]COD3049.0[m]C3049.2[m]CAPT3049.5[m]CAPT3050.4[m]CAPT3051.0[m]C3051.8[m]CAPT3052.0[m]CAPT3052.0[m]COD3052.4[m]CAPT3052.7[m]CAPT3053.2[m]CAPT3053.8[m]C3054.0[m]COD3054.2[m]CAPT3054.4[m]CAPT3054.6[m]CAPT3055.0[m]C3055.3[m]CAPT3055.3[m]COD3055.9[m]CAPT3056.5[m]C3056.6[m]CAPT3057.5[m]CAPT3057.6[m]COD3058.7[m]CAPT3060.9[m]CAPT3061.0[m]C3078.0[m]C3094.0[m]C3125.5[m]C3131.0[m]C3142.0[m]C3155.5[m]C3171.0[m]C3190.0[m]C3212.0[m]C3220.5[m]C3235.8[m]C3236.8[m]C3238.3[m]C3240.0[m]C3240.3[m]C3241.3[m]C3242.8[m]C3244.0[m]C3244.5[m]C3245.8[m]C3247.0[m]C3248.3[m]C3249.8[m]C3251.3[m]C3254.0[m]C3255.5[m]C3256.0[m]C3257.3[m]C3258.5[m]C3259.0[m]C3261.0[m]C3263.0[m]C3264.5[m]C3266.0[m]C3268.0[m]C3280.0[m]C3285.5[m]C3289.0[m]C3334.5[m]C3340.0[m]C3349.0[m]C3362.0[m]C3376.0[m]C3383.0[m]C3386.7[m]C3392.5[m]C3399.0[m]C3408.0[m]C