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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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 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL GR9003761DIL BHC GR903844DIL GR37713853LDL CNL GR37713854MWD33053780RFT GR37973797RFT HP GR37733834RFT HP GR38273842SAT10003760 -
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 -
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 -
Pressure plots
Pressure plots The pore pressure data is sourced from well logs if no other source is specified. In some wells where pore pressure logs do not exist, information from Drill stem tests and kicks have been used. The data has been reported to the NPD, and further processed and quality controlled by IHS Markit.Pressure plots Document nameDocument formatDocument size [MB]pdf0.21