16/7-7 S
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General information
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Wellbore history
GeneralWildcat well 16/7-7 S is located in the southern end of the Sleipner Terrace in the Norwegian North Sea. The primary objective of the well was to evaluate the resource potential of the eastern segment of the A-North prospect in the Triassic Skagerrak Formation. The western segment had been drilled in 1982 by well 16/7-4, which proved gas and condensate in sandstones of Jurassic/Triassic age.Operations and resultsWell 16/7-7 S was spudded with the semi-submersible installation Stena Dee on 20 October 1997. The well was drilled to 2745 m (2473.3 TVD SS) in the Cretaceous section. The bottom hole assembly was lost and the well was sidetracked. Well was sidetracked from 1777 m and was drilled to TD = 2994 m (2704.8 m TVD SS) in the Skagerrak Formation. The final well with sidetrack was drilled with seawater down to 1146 m and with Ancotec oil based mud from 1146 m to TD.The well found high-volatile oil in Intra Draupne Formation Sandstone and Skagerrak Formation sandstone, from 2763 m (2517.2 m TVD SS) down to a Free Water Level at 2860.3 m (2596.9 m TVD SS). Logs, wire line pressure measurements, drill stem tests, and shows confirmed the hydrocarbon column. There were no shows or other hydrocarbon indications reported from above or below the reservoir sectionFive cores were cut in the interval 2735.5 - 2887.5 m in the Åsgard Formation, the Intra Draupne Formation Sandstone, and the Skagerrak Formation. All cores were cut in the final sidetrack hole. No wire line fluid samples were taken.The well was permanently abandoned on 29 December 1997 as an oil discovery.TestingTwo drill stem tests were performed. DST 1 tested the interval 2785 - 2852 m (2535.5 - 2590.2 m TVD SS) in the Skagerrak Formation. The well flowed at maximum 514 Sm3 oil/day on a 44/64" choke. The GOR was ca 517 Sm3/Sm3, the oil gravity was ca 59 deg API, and the specific gas gravity was 0.94 (air = 1). DST 2 tested the interval 2762 - 2852 m (2516.7 - 2590.2 m TVD SS), which includes the Intra Draupne Formation Sandstone in addition to the upper Skagerrak Formation. DST 2 flowed at maximum 563 Sm3 oil/day on a 44/64" choke, and the Production Logging Tool (PLT) indicated that most of the flow in this test came from the Intra Draupne Formation Sandstone. The GOR was ca 450 Sm3/Sm3, the oil gravity was ca 59 deg API, and the specific gas gravity was 0.94 (air = 1). The reservoir temperature was reported as 100 deg C in both tests. -
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]1160.002990.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12735.02761.6[m ]22767.52802.8[m ]32803.52838.8[m ]42839.52875.5[m ]52875.52886.9[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]144.6Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
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 availableDSTDST12852.002785.00OIL09.12.1997 - 16:25YESDST0.000.0013.12.1997 - 23:20YESDSTDST 12572.002565.00OILYES -
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 typeCONDUCTOR30176.036179.00.00LOTSURF.COND.13 3/81146.017 1/21153.00.00LOTINTERM.9 5/82978.012 1/42994.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.02752278517.42.02852276217.4Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.015.6001002.011.400100Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.05130.7400.9405172.05632533500.7400.940450 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]AIT IPL DSI11462985CCL GR25452853CMR GR CALI27752944MDT GR27642904MWD LWD - DIR GR RES1762767MWD LWD - GR RES DENS NEU27672994MWD LWD - RLL GR28032887USIT180500VSP27402970VSP CSG3602730 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1038611193213421342182220823232340234023722606267627042704273127382763276327702770 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.52 -
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]pdf2.78pdf192.17 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured11531.5633.0OIL BASED17811.4335.0OIL BASED20001.3729.0OIL BASED20601.4343.0OIL BASED21851.4342.0OIL BASED27451.3734.0OIL BASED28591.4342.0OIL BASED29931.4339.0OIL BASED29941.4345.0OIL BASED