2/1-8
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General information
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Wellbore history
GeneralWell 2/1-8 was drilled on the Cod Terrace on the margin between the southern Vestland Arch and the Central Trough in the North Sea. The objective was to evaluate the Late Jurassic Gyda member reservoir sandstone (the "2/1-3 Sand") in the south-eastern part of the field.Operations and resultsAppraisal well 2/1-8 was spudded with the jack-up installation Neddrill Trigon on 28 July 1985 and drilled to TD at 4151 m (4159 m Logger's Depth) in the Triassic Skagerrak Formation. The well was drilled with spud mud down to 635 m, and with KCl/polymer mud from 635 m to 3474 m. At this depth the drill string got stuck while pulling out of the hole. It was freed after pumping pipelax into the hole. Following the pipelax pill and down to 3888 m the mud contained 1.0 - 2.5% oil. Drilling commenced with an oil-free KCl/polymer mud from 3888 m to TD. Below 2000 m logger's depth = driller's depth + 8 m. Above this depth there is no discrepancy. In the following all quoted depths are logger's depths.A 40 m thick Gyda member sandstone was penetrated at a depth of 3899.5 m. Cores from the reservoir proved a coarsening up sequence of very fine to medium grained sandstone. The reservoir was oil bearing throughout. Oil stain and gas bleed were observed in cores of very fine sandstones and siltstones from the underlying Farsund and Haugesund Formations. The Ula Formation at 4037 m was 26 m thick and water bearing. Traces of hydrocarbons were recorded from 3818 - 3821 m in the Early Cretaceous Åsgard Formation. These possibly result from leakage, up a minor fault, from Late Jurassic rocks. There were no significant hydrocarbon shows in any other section of the well.Three cores were cut in the Late Jurassic Gyda member, Farsund Formation, and Haugesund Formation, from 3906.0 to 3989.3 m with 95 to 100 % recovery. The RFT tool was run for pressure points, but no wire line fluid samples were taken.The well was permanently abandoned on 23 November 1985 as an oil appraisal well.TestingTwo drill stem tests were carried out in the Gyda member sandstoneDST1A tested the interval 3919 to 3926 m. This test was designed to evaluate the lower part of the reservoir; however it is thought that communication vas established behind casing with more permeable higher zones. Thus the results are unreliable. The test produced oil at a maximum rate of 1950 Sm3/day through a 16/64" choke. Oil gravity was 39.8 deg API and GOR was 633 Sm3/Sm3. The maximum flowing bottom hole temperature measured in the test was 154 deg C.DST1B tested the interval 3900.5-3926 m. Dry oil was produced at a maximum rate of 1010 Sm3/day through a 28/64" fixed choke. The oil gravity was 40 deg API and the GOR was 665 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]190.004152.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13898.03924.0[m ]23925.83931.0[m ]33953.03981.3[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]59.5Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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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 typeCONDUCTOR30193.036193.00.00LOTSURF.COND.20625.026635.01.76LOTINTERM.13 3/82000.017 1/22005.02.04LOTINTERM.9 5/83888.012 1/43898.02.12LOTOPEN HOLE4158.08 1/24158.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0391939266.42.03901392611.1Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.02.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.03050.8260.740992.09540.8250.825107 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL GR502000CST GR38904141CYBERDIP38874155CYBERLOOK38904145DLL MAFL GR CAL38874159GR SP36003832HP RFT GR39024140ISF BHC GR SP38774159ISF BHC MAFL GR CAL SP20003895ISF LSS GR SP193633ISF LSS MSFL GR CAL SP6252003LDL CNL NGL CAL38874159NGL SP38874159SHDT GR38874155 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1031790284728472901290930223065309731483148323035213610362136303630367837133717388038803900396540374037406340814081 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.69 -
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]pdf2.96pdf6.76 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1391.08100.0WATER BASED29.07.19851831.08WATER BASED29.07.19851881.0619.0WATER BASED05.08.19852151.0620.016.0WATER BASED05.08.19853731.0915.015.0WATER BASED05.08.19855361.0920.019.0WATER BASED07.08.19856351.1217.017.0WATER BASED08.08.19856401.1828.05.8WATER BASED08.08.19859201.2323.05.8WATER BASED13.08.198511151.2822.05.8WATER BASED12.08.198512801.3023.06.2WATER BASED13.08.198514291.3322.05.8WATER BASED15.08.198516321.3525.05.8WATER BASED19.08.198517881.4123.05.8WATER BASED19.08.198517881.5021.06.2WATER BASED19.08.198518171.5025.06.2WATER BASED17.08.198519711.5630.06.7WATER BASED21.08.198520001.5827.55.3WATER BASED18.09.198520051.5727.04.8WATER BASED26.08.198520051.5623.07.2WATER BASED21.08.198520051.5831.06.2WATER BASED23.08.198520051.593531.076.2WATER BASED26.08.198520051.5935.07.2WATER BASED26.08.198520051.5628.04.8WATER BASED26.08.198520051.5627.04.3WATER BASED27.08.198520051.5637.011.5WATER BASED29.08.198520051.5720.03.8WATER BASED02.09.198520051.5838.011.5WATER BASED02.09.198520091.5834.08.6WATER BASED02.09.198523451.5837.07.7WATER BASED03.09.198523651.5937.07.2WATER BASED04.09.198525091.5837.06.7WATER BASED05.09.198527061.5835.07.7WATER BASED06.09.198528781.5837.011.0WATER BASED09.09.198528941.5827.05.8WATER BASED09.09.198529521.5817.05.8WATER BASED09.09.198529941.5836.07.7WATER BASED10.09.198530001.5830.07.2WATER BASED11.09.198530951.5835.09.6WATER BASED12.09.198531711.5824.06.7WATER BASED13.09.198531961.5824.59.1WATER BASED16.09.198532221.5821.04.8WATER BASED16.09.198532541.5824.55.3WATER BASED16.09.198533441.5827.05.8WATER BASED17.09.198534321.5822.55.3WATER BASED19.09.198535781.5826.04.8WATER BASED20.09.198536021.6135.07.2WATER BASED18.11.198536601.6027.06.2WATER BASED23.09.198537231.6232.57.2WATER BASED23.09.198537231.6237.56.2WATER BASED23.09.198537231.6229.05.8WATER BASED24.09.198537231.6123.04.8WATER BASED25.09.198537361.6231.06.7WATER BASED26.09.198537751.6237.06.7WATER BASED27.09.198538161.6241.08.6WATER BASED30.09.198538321.6438.07.2WATER BASED30.09.198538441.6437.07.2WATER BASED01.10.198538841.6435.07.7WATER BASED01.10.198538881.6832.05.8WATER BASED02.10.198538881.6933.06.2WATER BASED07.10.198538881.6930.56.2WATER BASED08.10.198538881.6932.57.2WATER BASED08.10.198538981.5624.56.2WATER BASED08.10.198539261.5624.05.8WATER BASED09.10.198539541.5625.05.8WATER BASED09.10.198539811.5629.06.7WATER BASED10.10.198540151.5635.07.7WATER BASED11.10.198540511.5633.57.2WATER BASED14.10.198540921.5630.06.7WATER BASED14.10.198541511.5729.05.8WATER BASED14.10.198541511.5726.55.3WATER BASED15.10.198541511.5726.55.3WATER BASED16.10.198541511.5726.55.3WATER BASED17.10.198541511.5725.55.1WATER BASED18.10.198541511.5824.05.8WATER BASED21.10.198541511.5823.05.8WATER BASED21.10.198541511.5822.05.3WATER BASED21.10.198541511.5723.06.7WATER BASED22.10.198541511.5722.06.7WATER BASED23.10.198541511.5620.03.8WATER BASED29.10.198541511.5518.04.8WATER BASED29.10.198541511.5717.04.3WATER BASED29.10.198541511.6030.08.2WATER BASED29.10.198541511.6030.08.2WATER BASED31.10.198541511.6030.08.6WATER BASED01.11.198541511.6032.09.1WATER BASED01.11.198541511.6034.010.6WATER BASED04.11.198541511.6032.09.1WATER BASED05.11.198541511.609.1WATER BASED07.11.198541511.6032.08.6WATER BASED07.11.198541511.6032.08.6WATER BASED11.11.198541511.6029.59.1WATER BASED11.11.198541511.6031.08.6WATER BASED11.11.198541511.6034.09.6WATER BASED11.11.198541511.6038.09.6WATER BASED12.11.198541511.6035.07.2WATER BASED18.11.198541511.5726.06.2WATER BASED21.10.198541511.5520.05.8WATER BASED24.10.198541511.5520.05.8WATER BASED29.10.198541511.6127.07.2WATER BASED01.11.198541511.6038.09.6WATER BASED18.11.1985 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory3890.1[m]CAPT3898.2[m]CAPT3900.0[m]CAPT3901.8[m]CAPT3901.9[m]CAPT3902.9[m]CAPT3903.4[m]CAPT3904.9[m]CAPT3905.6[m]CAPT3907.5[m]CAPT3909.7[m]CAPT3910.7[m]CAPT3912.7[m]CAPT3914.3[m]CAPT3916.4[m]CAPT3919.5[m]CAPT3921.4[m]CAPT3923.4[m]CAPT3926.4[m]CAPT3928.4[m]CAPT3930.4[m]CAPT3932.4[m]CAPT3934.4[m]CAPT3936.4[m]CAPT3938.4[m]CAPT3940.4[m]CAPT3942.4[m]CAPT3946.4[m]CAPT3948.4[m]CAPT3950.4[m]CAPT3952.4[m]CAPT3954.4[m]CAPT3956.4[m]CAPT3958.4[m]CAPT3960.4[m]CAPT3962.4[m]CAPT3962.4[m]CAPT3964.4[m]CAPT3968.4[m]CAPT3970.4[m]CAPT3972.4[m]CAPT3974.4[m]CAPT3976.4[m]CAPT3978.4[m]CAPT3980.4[m]CAPT3981.4[m]CAPT3990.0[m]DCAPT3996.0[m]DCAPT3999.0[m]DCAPT4002.0[m]DCAPT4005.0[m]DCAPT4008.0[m]DCAPT4011.0[m]DCAPT4014.0[m]DCAPT4017.0[m]DCAPT4020.0[m]DCAPT4023.0[m]DCAPT4026.0[m]DCAPT4029.0[m]DCAPT4032.0[m]DCAPT4035.0[m]DCAPT4038.0[m]DCAPT4041.0[m]DCAPT4044.0[m]DCAPT4047.0[m]DCAPT4050.0[m]DCAPT4053.0[m]DCAPT4056.0[m]DCAPT4059.0[m]DCAPT4062.0[m]DCAPT4065.0[m]DCAPT