31/2-15
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General information
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Wellbore history
GeneralWell 31/2-15 was drilled in the northern part of the Troll West oil and gas province to evaluate reservoir quality and development in the northern part of the Troll West accumulation, and to establish fluid contacts in an undrilled fault compartment.Operations and resultsAppraisal well 31/2-15 was spudded with the semi-submersible installation Borgny Dolphin on 10 September 1984 and drilled to TD at 1677 m in the Middle Jurassic Fensfjord Formation. No major problems were encountered in the operations. The well was drilled with seawater and hi-vis pills down to 810 m, with KCl/polymer mud from 810 m to 1460 m, and with chalk mud (calcium chloride/calcium carbonate) from 1460 m to TD.Top reservoir was encountered at 1482 m as prognosed, but the age of the upper part was found to be of Paleocene and not Late Jurassic age. The expected Sognefjord Formation came in at 1515 m. The well thus correlate with the situation in well 31/2-18 and 31/2-18 A. Both the Paleocene sand and the Sognefjord Formation sand were gas filled, and the gas continued down to a low permeable micaceous gas/oil transition zone at 1561 m to 1567 m. Testing and sampling proved no mobile oil down to at least 1567 m, and the free oil level was concluded to be very close to the Field-GOC at 1572 m (1547 m SS). The OWC was unambiguously placed at 1583 m, in a highly permeable sand. No shows were recorded above 1482 m or below 1583 m. From petrophysical analysis there were indications of gas saturation in poor quality formation within a 10 m interval below top Fensfjord. However an RFT sample from his interval contained no oil, only gas and brine.Twelve cores were cut from 1486 m to 1595 m from the lower Paleocene, the Late Jurassic and Sognefjord Formation, and into the Heather Formation. A total of 4 RFT samples were taken. Of these 2 initial failed because of tight formation and seal failure while brine and gas were recovered from the samples at 1637 and 1568 m.The well was permanently abandoned on 15 November as a gas and oil appraisal.TestingTwo tests were performed in the Late Jurassic sequence. Test 1 from 1572 m to 1580 m produced oil at rates up to 570 Sm3 /day. The GOR was 54 Sm3/Sm3 and the oil gravity was 28 deg API. Test 2 from 1564 m to 1567 m had the objective to establish hydrocarbon type in the gas/oil transition zone. It gave initially no flow, but after displacing the tubing content partially to nitrogen a small flow of gas was established (10000 m3 gas/day). The gas contained only trace amounts of condensate. -
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]490.001676.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11486.01491.6[m ]21493.01499.8[m ]31501.01501.9[m ]41503.01507.5[m ]51510.01516.6[m ]61516.51520.5[m ]71520.01528.9[m ]81530.01532.5[m ]91533.01540.2[m ]101541.01559.0[m ]111559.01574.4[m ]121577.01588.2[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]91.6Cores 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 availableDSTTEST11572.001584.0018.10.1984 - 00:00YES -
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 typeCONDUCTOR30466.036477.00.00LOTSURF.COND.20800.526810.01.38LOTINTERM.13 3/81444.017 1/21460.01.62LOTINTERM.9 5/81663.012 1/41677.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL GR6251442CBL VDL GR8501631DLL MSFL GR14441671ISF BHC GR466808ISF BHC GR8001437ISF BHC GR14441676LDL CNL GR466808LDL CNL GR8001100LDL CNL GR11001436LDL CNL SGR14441676PCT15401600RFT14961562RFT14961662RFT14961662RFT15621637RFT15621637SHDT GR14441674SWS580VELOCITY4501676WST6801660 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit3686801200120012561316148215041515151515591636 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.27 -
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]pdf7.84pdf1.27pdf0.41pdf1.79pdf0.95pdf1.94pdf3.22pdf1.32pdf1.33pdf1.14pdf0.88pdf0.72pdf0.89pdf1.18pdf0.59pdf17.91pdf2.99pdf2.19pdf0.26pdf0.45 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4301.039.034.0WATER BASED11.09.19844771.03WATER BASED12.09.19844801.0315.060.0WATER BASED13.09.19848101.036.031.0WATER BASED14.09.19848101.036.031.0WATER BASED16.09.19848101.03WATER BASED17.09.19848101.2620.019.0WATER BASED18.09.19848101.036.031.0WATER BASED16.09.19848101.03WATER BASED16.09.19848101.03WATER BASED17.09.19848101.2620.019.0WATER BASED18.09.19848101.03WATER BASED16.09.198410691.2627.018.0WATER BASED19.09.198414401.2918.018.0WATER BASED20.09.198414601.2916.016.0WATER BASED23.09.198414601.2714.016.0WATER BASED23.09.198414601.2714.016.0WATER BASED23.09.198414741.2114.018.0WATER BASED25.09.198414931.2115.019.0WATER BASED25.09.198415101.2115.019.0WATER BASED26.09.198415211.2115.019.0WATER BASED27.09.198415301.2115.019.0WATER BASED29.09.198415381.2115.019.0WATER BASED29.09.198415621.2118.019.0WATER BASED29.09.198415641.20WATER BASED01.11.198415721.20WATER BASED17.10.198415951.2117.020.0WATER BASED01.10.198416341.20WATER BASED14.10.198416341.20WATER BASED15.10.198416341.20WATER BASED16.10.198416341.20WATER BASED15.10.198416341.20WATER BASED16.10.198416381.2318.021.0WATER BASED08.10.198416381.2217.019.0WATER BASED10.10.198416381.2318.021.0WATER BASED11.10.198416381.2318.021.0WATER BASED14.10.198416381.20WATER BASED14.10.198416381.2217.019.0WATER BASED10.10.198416381.2318.021.0WATER BASED11.10.198416381.2318.021.0WATER BASED14.10.198416381.20WATER BASED14.10.198416630.00WATER BASED21.10.198416631.2212.019.0WATER BASED10.10.198416771.2318.021.0WATER BASED08.10.198416771.2419.021.0WATER BASED08.10.198416771.2420.021.0WATER BASED08.10.198416771.2419.021.0WATER BASED08.10.198416771.2319.021.0WATER BASED03.10.198416771.2420.021.0WATER BASED08.10.198416771.2318.021.0WATER BASED08.10.1984 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1493.1[m]COD1493.2[m]COD1493.3[m]COD1493.6[m]COD1493.6[m]COD1493.7[m]COD