7/12-7
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General information
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Wellbore history
GeneralWell 7/12-7 was drilled on the South East flank of the Ula Field. The objective was to identify an optimal location and depth for a planned water-injection well by appraising the oil/water contact in this area.Operations and resultsAppraisal well 7/12-7 was spudded with the semi-submersible installation Vildkat Explorer on 20 June 1989 and drilled to TD at 3855 (3847 m TVD) m in the Late Jurassic Ula Formation. Drilling proceeded without any significant problems. The well was drilled with seawater and bentonite down to 174 m, with seawater/bentonite/spercell/CMC EHV mud from 174 to 1008 m, and with oil based Safemul mud from 1008 m to TD.Top reservoir was encountered at 3772 m (3765.5 m TVD) and the reservoir was oil bearing. Cores had oil shows down to the base of the last core at 3842 m. A well defined OWC or free water level was not found, though water saturations were seen to rise to the range 60-90% at ca 3819 m. Core porosity and permeability, RFT tests, and geochemical analysis showed a division between producible and residual oil to at 3815 m. From this it was concluded that that the lower contact for producible oil at the Ula East was ca 290 m deeper than at Ula West. Pressure measurements proved communication with the pressure-depleted parts of the Ula Field.Four cores were cut in the well in the Ula Formation in the interval 3800 to 3842.2 m. Core depths are ca 2 m deeper than loggers' depth. Segregated fluid samples were taken at 3797 m, 3834 m and 3842 m. The 2 3/4 gallon chambers from 3834 and 3842 m and the PVT 1 gallon chamber from 3834 m were drained at surface and contained water with indications of oil. On-shore geochemical analysis of the PVT 1 gallon chamber from 3842.2 m showed that it contained 90/10 water/diesel from the drilling mud. The 2 3/4 gallon chamber from 3797 m contained oil from the reservoir.The well was suspended on 26 July 1988 as a possible injector. It was classified as an oil appraisal.TestingNo drill stem test was performed. -
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]3290.003797.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13800.03801.6[m ]23801.63810.0[m ]33810.93829.0[m ]43829.43842.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]40.7Cores 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 typeCONDUCTOR32169.0670.00.00LOTINTERM.13 3/81003.017 1/21008.01.89LOTINTERM.9 5/82649.012 1/42620.01.98LOTLINER73768.08 1/23800.01.91LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL GR9003761DIL BHC GR903844DIL GR37713853LDL CNL GR37713854MWD33053780RFT GR37973797RFT HP GR37733834RFT HP GR38273842SAT10003760 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit9526522652269227602791285828583009321133323332343936623662369937723772 -
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]pdf8.76 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1451.51OIL BASED27.07.198829961.5033.017.0WATER BASED06.07.198830541.5033.620.0WATER BASED07.07.198832201.5032.617.0WATER BASED08.07.198834830.9112.510.0OIL BASED27.07.198835181.5031.617.0WATER BASED12.07.198836881.5160.037.0OIL BASED27.07.198837841.5215.414.0WATER BASED12.07.198837891.5232.616.0WATER BASED12.07.198837971.5234.618.0WATER BASED14.07.198837971.5233.617.0WATER BASED14.07.198837971.5234.618.0WATER BASED15.07.198837971.5630.0WATER BASED27.07.198838000.9010.019.0OIL BASED27.07.198838010.918.811.0OIL BASED27.07.198838110.9110.49.0OIL BASED27.07.198838300.91OIL BASED27.07.198838430.9112.510.0OIL BASED27.07.198838520.9113.010.0OIL BASED27.07.198838520.9013.411.0OIL BASED27.07.198838981.5033.617.0WATER BASED11.07.1988