34/7-13
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General information
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Wellbore history
GeneralWell 34/7-13 was drilled in the north western part of block 34/7 on the Snorre West prospect. The prospect is divided into two main fault segments by a SW NE trending fault with a throw of 60 m. The well was located in the southern part of the two segments. The primary purposes of the well were to explore the Snorre West prospect and to test a possible extension of the Statfjord East Field in a northward direction. The main target of the well was sandstones of the Middle Jurassic Brent Group. Secondary target was sandstones of the Early Jurassic Statfjord Formation.Operations and resultsWildcat well 34/7-13 was spudded with the semi-submersible installation Treasure Saga on 19 February 1988 and drilled to TD at 2994 m in the Late Triassic Lunde Formation. Drilling proceeded without significant problems, but up to 21 deg deviation in the deepest section of the well caused 11 m deviation between MD and TVD at TD. Shallow gas was encountered at 459 m, but it did not cause any technical problems. The well was drilled with spud mud down to 434, with Gel mud from 434 m to 973 m, with KCl mud from 973 m to 2682 m, and with gel mud from 2682 m to TD.Above the Jurassic the well penetrated mainly claystones with the exception of the Utsira Formation and some sandstone intervals between 1265 and 1325 m in the Hordaland Group. The Jurassic comprised the Middle Jurassic Brent Group, and the Early Jurassic Dunlin Group and Statfjord Formation. The Triassic comprised the Late Triassic upper Lunde Formation. The sandstones of the Brent Group, the Etive Formation, were encountered at 2492.5 m (TVD: 2490 m). The Etive Formation proved oil bearing, and the OWC was calculated to be at 2505.5 m (TVD: 2503 m). This was a thinner oil column than prognosed and the resources for the prospect were thus reduced compared to what was expected.The sandstones of the Statfjord Formation proved water bearing.First sign of petroleum hydrocarbons (C2 - C3) were reported at 2260 m. From 2285 m weak oil shows were seen in sand stringers. Over the reservoir and down to approximately 2510 m good oil shows were observed. Below 2510 m oil shows got weaker but traces were seen down to 2590 m.Five cores were cut in the interval 2496 - 2587.8 m. A total of 5 cores were cut throughout this section with 99 % recovery. A sixth core was cut from 2873 to 2890.5 m in the Statfjord Formation. FMT samples were taken at 2493.4 m (oil), 2494.4 m (oil), and 2503.7 m (water contaminated with mud filtrate). Single stage flash of the sample from 2493.4 m gave a GOR of 84.3 Sm3/Sm3, an oil density of 0.8392 g/cm3, and a gas gravity of 0.925 (air = 1).The well was permanently abandoned on 13 April 1988. It is classified as an oil appraisal on the Vigdis Discovery.TestingOne DST was performed in the interval 2498.1 - 2501.1 m in the Etive Formation. At the end of a 6.8 hours flow period, "Formation characteristics flow", the well produced 935 Sm3/day of oil with a GOR of 49 Sm3/Sm3 through an 11.1 mm choke. In the beginning of the main flow period the maximum recorded oil rate was 1350 Sm3/day through a 16 mm choke. The GOR in this flow was 51 Sm3/Sm3 and the oil density was 0.840 g/cm3. At the end of the main flow the well produced with 30-35% water cut. Sand production was also observed. Maximum down-hole temperature in the test (measured during main flow) was 90 deg C.A second DST was omitted due to problems caused by sand production. -
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]440.002994.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12496.02500.0[m ]22500.02515.3[m ]32515.52532.0[m ]42532.02559.6[m ]52560.02587.7[m ]62873.02889.9[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]108.0Cores 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 availableDSTDST1,12504.002500.0005.04.1988 - 14:50YES -
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 typeCONDUCTOR30429.036429.00.00LOTSURF.COND.20957.026973.01.59LOTINTERM.13 3/81843.017 1/21875.01.81LOTINTERM.9 5/82667.012 1/42682.02.03LOTOPEN HOLE2994.08 1/22994.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.02501250416.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.034.00015.00088Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.01350688500.84051 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL GR7501842CBL VDL GR10002664CBL VDL GR23702550CNL CDL GR18422682CNL CDL GR26642992COREGUN00COREGUN24962587COREGUN28732890DIFL LS BHC GR9571855DIFL LS BHC GR18422681DIFL LS BHC GR26642993DIPLOG23002678DIPLOG26672993DLL GR23002600FMT24942563FMT28762960MWD DLWD - GR RES DIR TEMP4342994VSP11152990 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit3081073108512671323167016701724185218522097247824782485249324932523259826002600267027422758285929622962 -
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]pdf12.67 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4341.05WATER BASED25.03.19885071.125.012.0WATER BASED25.03.19888901.164.07.7WATER BASED24.02.19889701.16WATER BASED25.03.19889701.164.07.2WATER BASED25.02.19889731.1221.013.9WATER BASED02.03.19889731.144.06.8WATER BASED24.02.198813481.1320.09.6WATER BASED02.03.198814791.2523.010.1WATER BASED02.03.198816811.4526.011.5WATER BASED03.03.198818751.5033.013.5WATER BASED03.03.198818751.5033.013.5WATER BASED04.03.198818751.5032.011.5WATER BASED07.03.198818751.5032.012.5WATER BASED07.03.198818751.5033.013.5WATER BASED07.03.198818751.5031.012.0WATER BASED08.03.198819921.5530.010.6WATER BASED14.03.198821001.6127.06.3WATER BASED25.03.198821001.6127.06.3WATER BASED28.03.198821001.6426.07.7WATER BASED16.03.198821001.6120.04.8WATER BASED18.03.198821001.6125.06.3WATER BASED22.03.198821001.6127.06.3WATER BASED24.03.198821001.6124.05.8WATER BASED18.03.198821001.6120.06.3WATER BASED21.03.198821001.6127.05.8WATER BASED25.03.198821061.6035.09.1WATER BASED14.03.198822321.6033.08.2WATER BASED14.03.198824041.6528.07.7WATER BASED15.03.198824701.5015.03.9WATER BASED11.04.198824921.5016.04.4WATER BASED11.04.198824921.5018.06.8WATER BASED11.04.198824921.5016.04.4WATER BASED06.04.198824921.5016.04.4WATER BASED08.04.198824921.5016.04.4WATER BASED05.04.198824921.5016.04.4WATER BASED07.04.198824951.6525.06.8WATER BASED15.03.198824951.6527.07.7WATER BASED15.03.198825321.6526.07.7WATER BASED16.03.198825891.6119.06.3WATER BASED21.03.198826901.6126.06.3WATER BASED28.03.198827771.6129.07.7WATER BASED28.03.198827771.6129.07.7WATER BASED29.03.198827771.6126.07.2WATER BASED30.03.198827771.6126.07.2WATER BASED05.04.198828761.6126.07.2WATER BASED05.04.1988 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory2696.3[m]COD2696.5[m]COD