25/2-13
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General information
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Wellbore history
GeneralWell 25/2-13 was drilled in the central part of the Viking Graben, east of the Frigg area. The block straddles the eastern flank of the graben and the north-western part of the Utsira High. It was the first appraisal well on the 25/2-5 discovery, which discovered oil in different reservoirs of the Vestland Group and the Statfjord Formation. The structure is a north-south trending horst, which is located on a terrace in the southern part of the block. Well 25/2-13 was drilled close to a major normal fault bounding the structure. The main objective was to evaluate the western panel. The well should test the fluid columns in both the Vestland Group and the Statfjord Formation, obtain data for fluid characterisation and productivity, and try to define the hydrocarbon contacts of the reservoirs.Operations and resultsAppraisal well 25/2-13 was spudded 6 June 1989 by the semi-submersible installation West Vanguard drilled to TD at 3909 m in the Triassic Smith Bank Formation. The well was drilled to 13" 3/8 casing point (2043 m) without problems, but at 2178 m the bit got stuck and a sidetrack was needed. The sidetrack was kicked off from 2070 m. The first attempt failed, but the second was successful. During coring of the Vestland Group, the core barrel was lost in hole and a second sidetrack was decided after unsuccessful fishing. This sidetrack was kicked off from 3306. The mud that was used in the Jurassic section (3318 - 3887 m) was an FCL type mud which was based on fresh water with added bentonite, polymers, lignosulfonate and barite.Top Vestland Group came in at 3342 m as prognosed, and with mobile hydrocarbons in two layers; oil in the top ca 40 - 60 m of the reservoir with an unclear OWC in the interval 3382 - 3415 m, and with oil shows down to 3423 m; and gas-condensate in an isolated layer in the Lower Vestland Group with a gross thickness = 33 m. However, the reservoir properties in the Vestland Group were not as good as in 25/2-5. Top Statfjord came in at 3695.5 m, 50 m deeper than prognosed with thickness as expected, but with mobile oil only in a thin zone at the very top. A very tentative OWC was placed at 3709 m, based on RFT pressure data logs, and some moveable oil in DST 2A. Fair shows were recorded down to 3729 m.A total of 19 cores were cut in this well. Cores 1 and 2 were cut in the original hole from 3340 to 3394.5 m, while cores 3 to 19 were cut in the sidetracked hole from 3387 to 3468.5 m. The core to log depth shifts for cores #1 to #7 are in the range 2.75 to 7.75 m. The core to log depth shifts for cores #11 to #19 are in the range 4.2 to 5.5 m. RFT samples were taken at 3696.5 m (mud filtrate with traces of oil very little gas) and 3727.5 m (mud filtrate with very little gas).The well was suspended 25 January 1990 as an oil / gas / condensate appraisal.TestingSeven drill stem tests were conducted in this well (DST 1,2A & 2B, 3A & 3B, 4, 5). Tests 1 and 2 were conducted in the Statfjord Formation while tests 3, 4 and 5 were conducted in the Vestland Group.DST #l tested the interval 3759 - 3785 m and produced a total of 42.5 m3 formation water. The final shut-in temperature was 124.4 deg C.DST #2A tested the interval 3706 - 3713 m, which produced no formation fluids to surface.DST #2B tested the interval 3695 - 3698 m in addition to the DST2 #A interval. The test flowed 69 sm3 oil and 29400 Sm3 gas /day on a 16/64" choke with a WHP of 85 bar and GOR of 425 sm3/sm3. The oil density was 0.821 g/cm3. The final shut-in temperature was 122.8 deg C.DST #3A tested the interval 3480 - 3491. This zone was very tight and flowed 154 litres only. Due to the low rates the movable formation fluid could not be identified. The test confirmed that the zone was in a separate and higher pressure regime than the Vestland Group hydrocarbon reservoirs above it.DST #3B tested the intervals 3437 - 3447 plus 3449.8 - 3460 in addition to the DST #3A interval. The test flowed 242000 sm3 gas-condensate /day with a GOR of 1115 sm3/sm3 and WHP of 170 bar on a 32/64" choke. The condensate density was 0.789 g/cm3. The final shut-in temperature was 115 deg C.DST #4 tested the interval 3411.5 - 3423 and produced a total of 2856 litres Formation water. The final shut-in temperature was 112.8 deg C.DST #5 tested the intervals 3343 - 3370 plus 3376.5 - 3382. The test flowed 651 sm3 oil and 213600 Sm3 gas /day on a 40/64" choke with a WHP of 125 bar and GOR of 328 sm3/sm3. The oil density was 0.825 g/cm3 and the gas gravity was 0.816 (air = 1). The final shut-in temperature was 111.8 deg C. -
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]205.003907.50 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13340.03341.8[m ]23367.03394.8[m ]33387.03406.0[m ]43405.03423.0[m ]53429.03441.0[m ]63441.03469.0[m ]73459.03468.6[m ]83649.03667.1[m ]93667.13669.7[m ]113709.03726.3[m ]123727.03744.7[m ]133745.03763.0[m ]143763.03781.5[m ]153781.53792.0[m ]163792.03810.6[m ]173810.53828.8[m ]183829.03847.0[m ]193847.03854.2[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]280.8Cores 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 typeLaboratory3341.0[m]CAPT3341.5[m]CAPT3342.3[m]CAPT3344.6[m]CAPT3345.7[m]CAPT3353.3[m]CAPT3357.5[m]CAPT3367.6[m]CAPT3369.6[m]CAPT3371.6[m]CAPT3378.7[m]CAPT3379.6[m]CAPT3381.9[m]CAPT3397.5[m]CAPT3399.6[m]CAPT3404.7[m]CAPT3405.7[m]CAPT3410.4[m]CAPT3414.9[m]CAPT3418.0[m]CAPT3420.8[m]CAPT3422.7[m]CAPT3423.7[m]CAPT3426.2[m]CAPT3427.2[m]CAPT3433.0[m]CAPT3433.3[m]CAPT3439.3[m]CAPT3439.8[m]CAPT3444.2[m]CAPT3445.6[m]CAPT3446.0[m]CAPT3447.8[m]CAPT3450.9[m]CAPT3452.6[m]CAPT3457.4[m]CAPT3459.8[m]CAPT3460.1[m]CAPT3465.0[m]CAPT3465.0[m]CAPT3465.1[m]CAPT3468.5[m]CAPT3469.3[m]CAPT3469.6[m]CAPT -
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 availableDST2252.000.0014.02.1986 - 00:00NODSTDST2B2706.002713.0020.12.1989 - 00:00YESDSTDST3B3396.960.00WATER01.01.1990 - 00:00NODSTDST43403.003411.00WATER07.01.1990 - 15:43YESDSTDST53343.003382.00WATER15.01.1990 - 00:00YESDSTDST53343.003382.0015.01.1990 - 00:00YESDSTDST53343.003382.0015.01.1990 - 00:00YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit13943710672170217022402400258626512706270630323187326832863318331833293342334234093491349135653645369638873887 -
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]pdf34.10 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0378537744.72.0371337060.02.3371336956.33.13460343712.55.03382334315.8Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.010.00010.0001242.02.38.5001233.116.0001155.012.500112Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.02.02.369294000.8230.8804253.12102420000.8000.80011205.06502136000.8290.818330 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL CCL GR15753300CBL VDL GR13302044DIL BHC LDL GR7002022DIL LSS GR33003903DIL MSFL GR AMS SP33003529DIL SLS LDL GR20443319DLL MSFL GR36753900FMS GR32993700FMS GR36503812LDL CNL NGL33003529LDL CNL NGT34763901MWD - GR RES DIR2023908RFT33463418RFT33543489RFT34823886RFT36963696SHDT GR20443312 -
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 typeCONDUCTOR30199.036201.00.00LOTINTERM.20700.026714.01.20LOTINTERM.13 3/82043.017 1/22057.01.72LOTINTERM.9 5/83301.012 1/43315.01.90LOTLINER73903.08 1/23908.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured13141.1620.06.8WATER BASED18.09.198913311.1724.07.8WATER BASED18.09.198916311.1722.05.8WATER BASED18.09.198917471.1727.08.8WATER BASED19.09.198920361.1720.05.8WATER BASED20.09.198920571.1824.07.8WATER BASED21.09.198921881.2026.011.7WATER BASED25.09.198922381.2739.014.2WATER BASED04.10.198923011.2736.013.2WATER BASED05.10.198925021.2732.011.7WATER BASED09.10.198925021.2732.010.7WATER BASED06.10.198927391.2731.011.2WATER BASED09.10.198928071.2733.012.2WATER BASED10.10.198928751.2733.013.2WATER BASED12.10.198929381.2734.012.2WATER BASED12.10.198930091.2733.011.7WATER BASED13.10.198931591.2037.010.7WATER BASED07.11.198932011.2732.011.2WATER BASED16.10.198932151.2733.011.2WATER BASED17.10.198932821.2734.012.2WATER BASED18.10.198933151.2732.010.7WATER BASED19.10.198933401.2733.011.7WATER BASED27.10.198933951.2730.08.8WATER BASED27.10.198934231.2039.013.2WATER BASED07.11.198935251.2034.010.2WATER BASED08.11.198937991.2036.07.3WATER BASED21.11.198938111.2038.08.3WATER BASED22.11.198938471.2038.08.8WATER BASED22.11.198938561.2138.09.8WATER BASED23.11.198939081.2036.013.7WATER BASED24.11.1989 -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit3340.10[m ]3360.25[m ]3405.24[m ]3367.42[m ]3421.10[m ]3404.10[m ]3394.67[m ]3887.10[m ]3441.05[m ]3440.45[m ]3424.20[m ]3468.00[m ]3459.30[m ]3458.10[m ] -
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]pdf0.23