34/7-1
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General information
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Wellbore history
GeneralThe wildcat 34/7-1 was drilled on the E-structure northeast in block 34/7, on a location ca 9 km south-south west of the 34/4-1 Snorre Discovery well in the northern North Sea. The continuation of this structure was explored by well 34/4-4. The main objective of 34/7-1 was Late Triassic sandstones, which proved hydrocarbon bearing in 34/4-1 and 34/4-4.Operations and resultsWell 34/7-1 was spudded with the semi-submersible installation Vildkat on 9 May 1984 and drilled to TD at 2905 m in the Late Triassic Lunde Formation. The 26" hole was drilled and logged first as a 17 1/2" pilot hole to 1106 m as a precaution against shallow gas then opened up to 26" by using underreamer. Tight spots occurred in the 26" hole section. In the 17 1/2" hole the string got stuck at 1274 m. The string had to be backed off and was fished out of the hole. Some tight spots occurred in this section too. When running the 9 5/8" casing, lost returns were experienced three times and the casing was pulled out of the hole. A velocity log was run, and the well was plugged back to 2640 m by setting two cement plugs and the 9 5/8" casing was landed at 2632 m. The well was drilled with seawater and bentonite down to 1106 m and with polymer/KCl mud from 1106 m to TD.The Tertiary and Cretaceous sections were mainly composed of claystones, with sand development in lower the Pliocene and in the Late Miocene. The Triassic consisted of sandstones alternating with siltstones, claystones and minor marl.A major unconformity is observed at 2392 m between the Late Triassic and the Lower Cretaceous. Apart from this, four other unconformities are observed in the well, one in Cretaceous, between Albian and Coniacian, one between the Latest Maastrichtian and Late Paleocene, one between Late Eocene and Early Oligocene and one between Late Oligocene and Late Miocene. Hydrocarbons were encountered in the Triassic sandstones (Lunde Formation) from 2392 down to an OWC at 2586 m. The reservoir comprised a number of sandstones with an average porosity of 23.2% and an average water saturation of 36%. The net pay thickness is 93 m.The entire Triassic reservoir section from 2397 to 2623 m was cored in 10 cores with 97% recovery. Three RFT-chambers containing pressurized reservoir oil (2398 m, 2497 m and 2579 m) and one RFT-chamber containing water and mud filtrate (2593 m) were collected in the well.The well was permanently abandoned on 24 July 1984 as an oil appraisal.TestingThree drill stem tests were performed in the oil bearing section of the Lunde Formation. All three tests produced oil.Three drill stem tests were carried out in the oil zone of this reservoir, intervals (DST1), (DST2) and (DST3).DST1 produced from the interval 2574.0 - 2581.5 m. During the main flow period this test produced 897 Sm3/day through an 11 mm choke with a wellhead pressure of 186 bar. The GOR was measured to 84 Sm2/Sm3 at separator conditions of 44 bar and 43 deg C. During this flow the bottom hole temperature reached 96.1 deg C and the reservoir pressure was measured to 388.4 bar. The well produced clean oil with no water or sand after the initial clean up.DST2 produced from the interval 2455.0 - 2567.0 m. During the main flow period the well produced 509 Sm3/day through a 9.5 mm choke, with a wellhead pressure of 167 bar. The GOR was measured to 80 Sm3 /Sm3 at separator conditions of 46 bar and31 deg C. During this flow the bottom hole temperature reached 92.8 deg C. The well produced clean oil with no water or sand after it had cleaned up.DST3 produced from the interval 2409.7 - 2416.5 m. During the main flow period the well produced 1606 Sm3/day through a 17.5 mm choke, with a wellhead pressure of 146 bar. The GOR was measured to 60 Sm3/Sm3 at separator conditions of 72 bar and 63 deg C. During this flow the bottom hole temperature reached 91.7 deg C. The well produced clean oil with no water or sand after it had cleaned up.The bubble point pressures ranged from 174 to 182 bar, representing crude samples from the lower and the upper interval tested respectively (Ref. temp. 92-96 deg C). The dead oil density was 0.83 g/cm3, the gas gravity 0.93 (air = 1), the oil formation volume factor 1.47 Rm3 /Sm3 and the solution gas-oil-ratio in the range of 144-157 Sm3/Sm3. -
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]480.002903.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12394.02409.5[m ]22412.02432.9[m ]32435.02463.0[m ]42463.02490.0[m ]52490.02518.0[m ]62518.02545.0[m ]72545.02573.1[m ]82573.02594.0[m ]92595.02604.3[m ]102605.02623.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]222.8Cores 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 availableDSTDST12574.002581.00OIL01.07.1984 - 11:20YESDSTDST22467.002455.00OIL09.07.1984 - 13:00YESDSTDST32416.002409.0015.07.1984 - 19:50YES -
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 typeCONDUCTOR30476.036478.00.00LOTSURF.COND.201070.0261106.01.57LOTINTERM.13 3/81844.017 1/21870.01.92LOTINTERM.9 5/82632.012 1/42649.00.00LOTOPEN HOLE2905.012 1/42905.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.02581257411.02.0245524679.53.02410241717.5Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.018.00036.0002.03.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.0357200000.82620002.0509400000.825803.018151260000.83070 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BGL CST10721848CST11021838DLL MSFL GR23702618GR0478ISF BHC GR26102904ISF LSS GR10721852ISF LSS GR18412621ISF LSS GR CST4771106LDL CNL GR18412905LDL CNL GR23702622LDL GR10721854RFT23942619RFT25802736SHDT18392905VSP4772904 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit353115011701673167316961823182319332387238723922392 -
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]pdf17.20 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4201.03100.0WATER BASED10.05.19844781.0547.028.0WATER BASED10.05.19844781.0547.028.0WATER BASED10.05.19844781.05100.0WATER BASED10.05.19847001.0750.042.0WATER BASED10.05.198410371.1445.030.0WATER BASED13.05.198411061.1850.053.0WATER BASED20.05.198411061.1652.055.0WATER BASED20.05.198411061.1050.012.0WATER BASED16.05.198411061.1450.031.0WATER BASED15.05.198411061.1652.055.0WATER BASED20.05.198411061.1050.012.0WATER BASED16.05.198411061.0652.029.0WATER BASED16.05.198411061.1850.053.0WATER BASED20.05.198411061.0652.029.0WATER BASED16.05.198414221.2056.024.0WATER BASED23.05.198414221.2150.022.0WATER BASED25.05.198414221.1547.018.0WATER BASED22.05.198414221.2056.024.0WATER BASED23.05.198414221.2150.022.0WATER BASED25.05.198414501.2350.026.0WATER BASED25.05.198417631.3750.026.0WATER BASED29.05.198418701.4653.025.0WATER BASED29.05.198420671.5157.026.0WATER BASED01.06.198421941.5654.023.0WATER BASED04.06.198421941.5456.023.0WATER BASED01.06.198421941.5654.023.0WATER BASED04.06.198423941.6455.014.0WATER BASED25.06.198423941.6552.017.0WATER BASED25.06.198423941.6546.016.0WATER BASED25.06.198423941.6552.017.0WATER BASED25.06.198423941.6546.016.0WATER BASED25.06.198423971.5854.024.0WATER BASED04.06.198424121.6355.023.0WATER BASED04.06.198424361.6355.023.0WATER BASED06.06.198424361.6355.023.0WATER BASED06.06.198424361.6355.023.0WATER BASED06.06.198424751.6355.023.0WATER BASED07.06.198424911.6322.023.0WATER BASED08.06.198425321.6322.023.0WATER BASED12.06.198425621.6430.027.0WATER BASED12.06.198425911.6430.027.0WATER BASED12.06.198426061.7422.012.0WATER BASED02.07.198426061.7450.028.0WATER BASED28.06.198426061.7450.012.0WATER BASED29.06.198426061.7422.012.0WATER BASED02.07.198426061.6646.016.0WATER BASED27.06.198426061.7450.028.0WATER BASED28.06.198426061.7450.012.0WATER BASED29.06.198426231.6430.027.0WATER BASED18.06.198426231.6430.027.0WATER BASED14.06.198426231.6430.027.0WATER BASED18.06.198426291.7030.027.0WATER BASED18.06.198426501.6546.016.0WATER BASED27.06.198427601.7355.023.0WATER BASED18.06.198428381.7352.020.0WATER BASED18.06.198429051.6455.014.0WATER BASED22.06.198429051.7662.023.0WATER BASED18.06.198429051.6455.014.0WATER BASED22.06.1984 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1166.0[m]SWCRRI1170.0[m]SWCRRI1190.0[m]CRRI1210.0[m]CRRI1220.0[m]DCRRI1240.0[m]DCRRI1250.0[m]DCRRI1270.0[m]DCRRI1280.0[m]DCRRI1300.0[m]DCRRI1320.0[m]DCRRI1330.0[m]DCRRI1350.0[m]DCRRI1359.0[m]CRRI1370.0[m]DCRRI1390.0[m]DCRRI1410.0[m]DCRRI1420.0[m]DCRRI1438.0[m]DCRRI1450.0[m]DCRRI1460.0[m]DCRRI1480.0[m]DCRRI1510.0[m]DCRRI1520.0[m]DCRRI1540.0[m]DCRRI1550.0[m]DCRRI1570.0[m]DCRRI1580.0[m]DCRRI1610.0[m]DCRRI1630.0[m]DCRRI1640.0[m]DCRRI1660.0[m]DCRRI1670.0[m]DCRRI1838.0[m]SWCRRI1872.0[m]SWCRRI1886.0[m]DCRRI1905.0[m]SWCRRI1916.0[m]DCRRI1931.0[m]DCRRI1961.0[m]DCRRI1976.0[m]DCRRI1982.0[m]SWCRRI2006.0[m]DCRRI2036.0[m]CRRI2066.0[m]CRRI2070.0[m]SWCRRI2081.0[m]DCRRI2150.0[m]SWCRRI2186.0[m]SWCRRI -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit2615.50[m ]2612.20[m ]2602.70[m ]2676.50[m ]2757.30[m ]