7120/7-2
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General information
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Wellbore history
GeneralWell 7120/7-2 is located in the Snøhvit Field area. The primary of the well was to test possible hydrocarbon accumulations in sandstones of Middle to Early Jurassic age.Operations and resultsWildcat well 7120/7-2 was spudded with the semi-submersible rig West Vanguard on 26 May 1983 and drilled to TD at 2523 m, 5 meters into Late Triassic rocks. Due to boulders at the spud location the rig was moved 11 m north and respudded. A sand body with shallow gas was encountered at 378 m to 382.5 m and it was decided to set the 20" casing shoe above this sand. After setting this casing the rig was shut down due to strike from 3 June at 2400 hrs to 18 June at 1125 hrs. The well was drilled using gel mud down to 815 m, with gypsum/polymer mud from 815 m to 1515, and dispersed to a lignosulphonate (Unical) mud from 1515 m to TD.Hydrocarbon accumulations were discovered in the Middle Jurassic Stø Formation sandstone sequence from 2149.5 m down to a gas/water contact at 2228 m. Shows were recorded below 1809 m in the Cretaceous Kolje Formation. Organic geochemical analyses showed that TOC increases down through the Cretaceous, but generally the Cretaceous mudstones were regarded as immature, poor source rocks with a primary potential for gas. Entering into the silty shales and mudstones of the Late Jurassic Hekkingen Formation at 2107 m TOC increases abruptly above 3%. TOC continues to increase to 9 % at the base of the Hekkingen Formation. These shales are potentially very good source rocks for gas and condensate above ca 2120 metres and rich sources for light oil and gas below this depth. Maturity evaluation was difficult due to reworked material and cavings, but most likely the well is immature all through, possibly marginally mature below ca 2000 m. Five cores were cut in the sandstones from 2168 m to 2244 m. Four RFT samples were taken. Sample 1 was taken at 2150 m (gas, mud filtrate and film of condensate), sample 2 at 2151 m (gas, mud filtrate and condensate, sample 3 at 2225 m (mud filtrate and water), and sample 4 at 2220 m (mud filtrate and minor gas).The well was permanently abandoned on 21 August as a gas/condensate discovery.TestingOne DST was performed in the Stø Formation in the intervals 2168 m to 2179.8 m and 2153 m to 2164.8 m. The lower interval was intended for pressure monitoring to test possible communication between the two zones, but the pressure recordings failed. The test produced 702450 Sm3 gas and 31.5 Sm3 condensate /day on a 64/64 choke during the main flow. Condensate density was 0.77 g/cm3 and the gas gravity was 0.68 (air = 1) with a CO2 content of 5%. No H2S was recorded. This corresponds to a very dry gas condensate similar to the 7120/7 and 7120/8 hydrocarbon systems.> -
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]330.002520.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12166.02184.0[m ]22184.02190.0[m ]32190.02208.0[m ]42208.02226.8[m ]52226.82244.4[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]78.4Cores 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 availableDSTTEST12153.002180.0011.08.1983 - 18:55NO -
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 typeCONDUCTOR30325.536330.00.00LOTSURF.COND.20365.026367.00.00LOTINTERM.13 3/8800.017 1/2815.01.65LOTINTERM.9 5/81502.012 1/41515.01.80LOTLINER72523.08 1/22523.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.1218721930.01.2216821800.01.32153216425.4Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.11.21.385Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.11.21.3307020000.7700.68023400 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL GR263800CBL VDL GR2631502CBL VDL GR CCL13522370CST8151490CST15232508DLL MSFL GR21252300HDT GR8001512ISF BHC GR3651514ISF BHC GR21252516ISF BHC MSFL GR263411ISF BHC MSFL GR15022222LDL CNL GR325411LDL CNL NGT15142517LDL GR3651514RFT21502491RFT21512151RFT22192219RFT22252225SHDT GR15022517VELOCITY4002510 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit26338038094794710921092166619872017214121502150225623872435 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.44 -
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]pdf18.92pdf1.29 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2961.05spud mud4101.1045.029.0water based8251.1448.040.0water based15151.2552.021.0water based21151.3255.018.0water based25231.2053.011.0water based -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory700.0[m]DCPAS760.0[m]DCPAS780.0[m]DCPAS800.0[m]DCPAS840.0[m]DCPAS890.0[m]DC930.0[m]DC950.0[m]DCOD960.0[m]DCOD970.0[m]DCOD980.0[m]DCOD990.0[m]DCPAS1000.0[m]DC1000.0[m]DCPAS1000.0[m]DCOD1023.0[m]SWCPAS1050.0[m]SWCPAS1060.0[m]DCPAS1100.0[m]SWCPAS1100.0[m]DC1126.5[m]SWCPAS1140.0[m]DCOD1150.0[m]DCOD1152.5[m]SWCPAS1160.0[m]DCOD1160.0[m]DCPAS1185.0[m]SWCPAS1200.0[m]DC1218.0[m]SWCPAS1227.3[m]DCPAS1239.0[m]DCOD1247.5[m]SWCPAS1251.0[m]DCOD1257.0[m]DCPAS1260.0[m]DCOD1269.0[m]DCOD1272.8[m]DCPAS1299.0[m]DC1302.0[m]DCPAS1317.0[m]DCPAS1340.0[m]SWCPAS1370.0[m]SWCPAS1380.0[m]DCPAS1400.0[m]SWCPAS1404.0[m]DC1423.0[m]SWCPAS1437.0[m]DCPAS1452.0[m]DCPAS1470.0[m]SWCPAS1490.0[m]SWCPAS1497.0[m]DCPAS1500.0[m]DC1512.0[m]DCPAS1525.0[m]SWCPAS1542.0[m]DCPAS1557.0[m]DCPAS1572.0[m]DCPAS1587.0[m]SWCPAS1599.0[m]DC1602.0[m]DCPAS1617.0[m]DCPAS1632.0[m]DCPAS1647.0[m]DCPAS1677.0[m]DCPAS1690.0[m]DCPAS1701.0[m]DCPAS1701.0[m]DC1720.0[m]SWCPAS1737.0[m]DCPAS1752.0[m]DCPAS1767.0[m]DCPAS1790.0[m]SWCPAS1797.0[m]DC1812.0[m]DCPAS1827.0[m]DCPAS1842.0[m]DCPAS1857.0[m]DCPAS1872.0[m]DCPAS1887.0[m]DCPAS1899.0[m]DC1900.0[m]SWCPAS1917.0[m]DCPAS1932.0[m]DCPAS1962.0[m]DCPAS1977.0[m]DCPAS1992.0[m]DCPAS2001.0[m]DC2007.0[m]DCPAS2020.0[m]SWCPAS2031.0[m]DCPAS2040.0[m]DC2046.0[m]DCPAS2061.0[m]DCPAS2076.0[m]DCPAS2091.0[m]DCPAS2100.0[m]DC2107.0[m]SWCPAS2115.0[m]DCPAS2139.0[m]SWCPAS2139.0[m]DC2141.5[m]SWCPAS2147.0[m]SWCPAS2151.0[m]DC2166.0[m]DCPAS2181.0[m]CPAS2183.6[m]CPAS2184.5[m]CPAS2193.6[m]CPAS2202.7[m]CPAS2274.0[m]SWCPAS2292.0[m]DCPAS2306.5[m]SWCPAS2322.0[m]DCPAS2337.0[m]DCPAS2352.0[m]DCPAS2367.0[m]DCPAS2397.0[m]DCPAS2412.0[m]DCPAS2442.0[m]DCPAS2457.0[m]DCPAS2477.0[m]SWCPAS2492.0[m]DCPAS2502.0[m]DCPAS2517.0[m]DCPAS2520.0[m]DCPAS