7121/5-1
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General information
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Wellbore history
GeneralWildcat well 7121/5-1 is located on the eastern part of the Snøhvit Field. It was drilled about 75 m down flank on the Alpha-structure in the block. The Snøhvit structure consists of an east-west running horst and a rotated normal faulted block. The main objective in the well was to test possible reservoir rocks of Jurassic/Triassic age as seen in neighbouring wells.Operations and resultsWell 7121/5-1 was spudded with the semi-submersible installation West Vanguard on 7 June 1985 and drilled to TD at 3200 m. The rig was shut down from 16 June to 30 June due to a strike. Otherwise drilling proceeded without significant problems. The well was drilled with spud mud down to 865 m, with a gypsum/polymer mud from 865 m to 1925 m, and with polymer mud from 1925 m to TD.Top reservoir came in at 2369 m with hydrocarbons. From RFT pressure measurements the gas/oil contact was found at 2427.5 m and the oil/water contact at 2442 m. Logs displayed sands with possible hydrocarbons in Triassic sandstones, but increasing shale down hole reduced porosity/permeability and DST test confirmed a tight formation. Geochemical analyses showed immature rocks until 2250 m and marginal to significant maturity in Triassic/Jurassic rocks respectively. Nine cores were cut in the interval 2365 m to 2523 m in the Stø, Nordmela and Tubåen Formations. One core was cut from 3088 m to 3109 m in the Triassic Snadd Formation. Four RFT segregated samples were taken in the upper part of the Stø and Nordmela Formations from 2370 m to 2434 m, one in the Tubåen Formation at 2507 m, and one at 2802.7 m in the Snadd Formation. A small amount of condensate in the sample from 2370 m was the only reported liquid hydrocarbons from the RFT samples. Otherwise gas was recovered in the samples from 2424 m and 2370 m, while the sample from 2507 recovered mainly water/mud filtrate and minor gas. The sample from 2802.7 m contained only minor amounts of mud filtrate and no hydrocarbons. Some weak shows were recorded in the SnaddFormation. The well was permanently abandoned on 28 September 1985 as an oil and gas appraisal.TestingThree drill stem tests were performed. DST lA from 2802 m to 2820 m in Triassic sandstones gave no response from the formation. DST l tested the interval 2436 m to 2439 m near base of the Stø Formation. The 9-5/8" casing was first perforated with 6 shots/foot, and after that the well was re-perforated by 12 shots/foot (DST l RR) in an attempt to improve flowing rates. DST 1 produced oil and gas during the main flow at a rate of 229.1 Sm3 and 27190 Sm3, respectively through a 12.7 mm choke. The gas/oil ratio was 119 Sm3/Sm3. DST 2 perforated the interval 2394 m to 2403 m in the upper part of the Stø Formation. This test gave no response and the formation was considered tight. -
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]420.003197.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12365.02392.0[m ]22392.02400.4[m ]32400.42428.0[m ]42428.32442.0[m ]52442.02470.0[m ]62470.02498.0[m ]72498.02509.0[m ]82509.02509.0[m ]92509.42536.0[m ]103082.03103.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]191.3Cores 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 typeLaboratory500.0[m]DCGERH510.0[m]DCGERH520.0[m]DCGERH530.0[m]DCGERH550.0[m]DCGERH560.0[m]DCGERH570.0[m]DCGERH600.0[m]DCGERH610.0[m]DCGERH620.0[m]DCGERH630.0[m]DCGERH640.0[m]DCGERH650.0[m]DCGERH660.0[m]DCGERH670.0[m]DCGERH680.0[m]DCGERH690.0[m]DCGERH700.0[m]DCGERH710.0[m]DCGERH720.0[m]DCGERH730.0[m]DCGERH740.0[m]DCGERH750.0[m]DCGERH760.0[m]DCGERH770.0[m]DCGERH780.0[m]DCGERH790.0[m]DCGERH800.0[m]DCGERH810.0[m]DCGERH820.0[m]DCGERH830.0[m]DCGERH840.0[m]DCGERH850.0[m]DCGERH870.0[m]DCGERH900.0[m]DCGERH910.0[m]DCGERH920.0[m]DCGERH930.0[m]DCGERH940.0[m]DCGERH962.0[m]DCGERH974.0[m]DCGERH986.0[m]DCGERH998.0[m]DCGERH1019.0[m]DCGERH1031.0[m]DCGERH1043.0[m]DCGERH1067.0[m]DCGERH1079.0[m]DCGERH1091.0[m]DCGERH1115.0[m]DCGERH1127.0[m]DCGERH1139.0[m]DCGERH1151.0[m]DCGERH1169.0[m]DCGERH1181.0[m]DCGERH1193.0[m]DCGERH1200.0[m]SWCGERH1217.0[m]DCGERH1232.0[m]DCGERH1247.0[m]DCGERH1262.0[m]DCGERH1277.0[m]DCGERH1292.0[m]DCGERH1307.0[m]DCGERH1322.0[m]DCGERH1337.0[m]DCGERH1367.0[m]DCGERH1382.0[m]DCGERH1397.0[m]DCGERH1412.0[m]DCGERH1427.0[m]DCGERH1445.0[m]DCGERH1469.0[m]DCGERH1481.0[m]DCGERH1496.0[m]DCGERH1511.0[m]DCGERH1511.0[m]DCGERH1526.0[m]DCGERH1550.0[m]DCGERH1562.0[m]DCGERH1574.0[m]DCGERH1589.0[m]DCGERH1604.0[m]DCGERH1616.0[m]DCGERH1646.0[m]DCGERH1661.0[m]DCGERH1676.0[m]DCGERH1691.0[m]DCGERH1721.0[m]DCGERH1736.0[m]DCGERH1751.0[m]DCGERH1766.0[m]DCGERH1775.0[m]DCGERH1781.0[m]DCGERH1796.0[m]DCGERH1811.0[m]DCGERH1826.0[m]DCGERH1841.0[m]DCGERH1871.0[m]DCGERH1886.0[m]DCGERH1901.0[m]DCGERH1910.0[m]DCGERH1925.0[m]DCGERH1934.0[m]DCGERH1949.0[m]DCGERH1952.0[m]DCGERH1964.0[m]DCGERH1979.0[m]DCGERH1994.0[m]DCGERH2009.0[m]DCGERH2024.0[m]DCGERH2028.0[m]DCGERH2039.0[m]DCGERH2054.0[m]DCGERH2069.0[m]DCGERH2084.0[m]DCGERH2099.0[m]DCGERH2114.0[m]DCGERH2129.0[m]DCGERH2142.0[m]SWCGERH2144.0[m]DCGERH2159.0[m]DCGERH2174.0[m]DCGERH2189.0[m]DCGERH2204.0[m]DCGERH2218.0[m]SWCGERH2234.0[m]DCGERH2249.0[m]DCGERH2256.0[m]SWCGERH2264.0[m]DCGERH2270.0[m]DCGERH2285.0[m]DCGERH2294.0[m]DCGERH2305.0[m]DCGERH2310.0[m]SWCGERH2313.5[m]CGERH2314.0[m]SWCGERH2323.0[m]CGERH2327.0[m]SWCGERH2334.0[m]SWCGERH2344.0[m]SWCGERH2349.0[m]SWCGERH2355.0[m]SWCGERH2359.0[m]SWCGERH2365.0[m]CGERH2372.0[m]CGERH2380.0[m]CGERH2390.0[m]CGERH2391.0[m]CGERH2395.0[m]CGERH2399.0[m]DCGERH2400.0[m]CGERH2407.0[m]CGERH2429.0[m]CGERH2445.0[m]CGERH2452.0[m]CGERH2464.0[m]CGERH2473.0[m]CGERH2483.0[m]CGERH2490.7[m]CICHRON2492.0[m]CGERH2501.0[m]CGERH2509.0[m]CGERH2509.0[m]CICHRON2520.0[m]CGERH2531.0[m]CGERH2535.0[m]CGERH2535.9[m]CICHRON2546.0[m]CGERH2546.0[m]DCRRI2555.0[m]DCRRI2558.0[m]DCGERH2564.0[m]DCRRI2567.0[m]DCRRI2570.0[m]DCGERH2582.0[m]DCGERH2594.0[m]DCGERH2606.0[m]DCGERH2618.0[m]DCGERH2630.0[m]DCGERH2643.0[m]SWCGERH2654.0[m]DCGERH2666.0[m]DCGERH2672.0[m]SWCGERH2678.0[m]DCGERH2682.0[m]SWCGERH2687.0[m]SWCGERH2695.0[m]SWCGERH2702.0[m]DCGERH2714.0[m]DCGERH2726.0[m]DCGERH2738.0[m]SWCGERH2750.0[m]DCGERH2762.0[m]DCGERH2786.0[m]DCGERH2796.0[m]SWCGERH2810.0[m]DCGERH2822.0[m]DCGERH2842.0[m]SWCGERH2914.0[m]SWCGERH2948.0[m]SWCGERH2951.0[m]DCGERH3074.0[m]DCGERH3084.0[m]CGERH3091.0[m]CGERH3093.0[m]CGERH3116.0[m]DCGERH3164.0[m]DCGERH -
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 availableDSTDST12436.002439.0004.09.1985 - 00:15YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit35846046010051005103610361930223622922357236923692445250725722572266027382793 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.58 -
Geochemical information
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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]pdf44.00 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.1280228200.01.22436243912.72.0239424030.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.11.23.50016.300902.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.11.2229271900.8601192.0 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL GR4752726CET GR15002726CNL GR CASED23502500CST8601903CST19522738CST27553178DLL MSFL SP GR23492534ISF SONIC SMFL SP GR4193200LDL CNL GR4193200NGS19073201RFT HP23702518RFT HP25082662RFT ST23702507RFT ST28023118SHDT8483180TDT GR23502500TDT GR23502500TEMP10002000VSP4053200 -
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 typeCONDUCTOR30419.536423.00.00LOTSURF.COND.20849.526879.01.43LOTINTERM.13 3/81912.017 1/21929.01.59LOTINTERM.9 5/82739.012 1/42755.01.74LOTLINER73200.08 1/23200.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured8771.06600.016.0WATER BASED13.06.19858771.06600.013.5WATER BASED14.06.19858771.06600.013.5WATER BASED14.06.19858791.171200.09.3WATER BASED17.06.19858791.17WATER BASED17.06.19858791.17WATER BASED19.06.19858791.17WATER BASED20.06.19858791.001400.06.8WATER BASED01.07.19858791.06600.011.4WATER BASED17.06.19858791.17WATER BASED24.06.19858791.001400.06.8WATER BASED01.07.19858791.17WATER BASED24.06.19858791.171200.09.3WATER BASED17.06.19858791.17WATER BASED17.06.19858791.17WATER BASED19.06.19858791.17WATER BASED20.06.19858851.101500.07.6WATER BASED03.07.19858851.111600.08.9WATER BASED05.07.19858851.111600.08.9WATER BASED05.07.198513931.111500.09.7WATER BASED05.07.198517231.121500.06.3WATER BASED08.07.198518601.121500.07.2WATER BASED08.07.198519251.141700.08.4WATER BASED09.07.198519251.146000.06.8WATER BASED10.07.198519251.146000.06.8WATER BASED10.07.198520831.151500.08.1WATER BASED15.07.198521611.151600.08.0WATER BASED15.07.198522541.151600.07.6WATER BASED15.07.198523091.151600.08.0WATER BASED16.07.198523531.301900.08.5WATER BASED19.07.198523531.301900.08.5WATER BASED19.07.198523531.301900.07.6WATER BASED18.07.198523651.301900.010.2WATER BASED18.07.198523921.301900.07.6WATER BASED18.07.198524531.341800.011.0WATER BASED22.07.198525001.341700.09.3WATER BASED29.07.198525361.341700.010.0WATER BASED29.07.198525371.341700.010.0WATER BASED29.07.198525391.341700.09.3WATER BASED29.07.198525401.231200.05.0WATER BASED04.09.198525401.231000.04.6WATER BASED05.09.198525401.231000.05.5WATER BASED06.09.198525401.231000.05.1WATER BASED09.09.198525401.23900.04.2WATER BASED10.09.198525401.23900.04.2WATER BASED11.09.198525401.23900.04.2WATER BASED12.09.198525401.23800.04.2WATER BASED13.09.198525441.231400.06.3WATER BASED30.08.198525441.231400.05.9WATER BASED02.09.198525461.231500.07.2WATER BASED30.08.198525481.341700.09.7WATER BASED30.07.198525721.341900.09.3WATER BASED31.07.198526001.342200.09.7WATER BASED01.08.198526071.342000.09.7WATER BASED01.08.198526281.342100.09.3WATER BASED02.08.198526531.341900.010.2WATER BASED05.08.198526971.342100.010.6WATER BASED05.08.198527471.342100.09.7WATER BASED06.08.198527471.342100.09.7WATER BASED06.08.198527471.342100.09.7WATER BASED05.08.198527551.168.01900.0WATER BASED12.08.198527551.342100.09.3WATER BASED08.08.198527551.168.01900.0WATER BASED12.08.198527921.161700.08.5WATER BASED12.08.198528021.231500.06.7WATER BASED28.08.198528551.161700.08.0WATER BASED12.08.198529331.161500.08.5WATER BASED13.08.198529801.161500.08.0WATER BASED14.08.198530441.161600.07.2WATER BASED15.08.198530821.161600.07.2WATER BASED16.08.198531611.161500.07.6WATER BASED26.08.198531611.231400.07.2WATER BASED27.08.198531611.231500.07.2WATER BASED26.08.1985 -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit2505.00[m ]2507.00[m ]2512.35[m ]2514.35[m ]2517.00[m ]2524.65[m ]2526.65[m ]2530.00[m ]2535.35[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]pdf0.28