7/12-3 A
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General information
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Wellbore history
GeneralWell 7/12-3 A is a geological sidetrack to 7/12-3 on the western flank of the 7/12-2 Ula discovery in the North Sea. The primary objective was to establish the oil-water level in the Ula structure.The well is type well for the Mandal Formation.Operations and resultsOn 4 June 1977 appraisal well 7/12-3 A was kicked off from below the 13 3/8” casing shoe in well 7/12-3 at a depth of 1720. The semi-submersible installation Norskald drilled the well to TD at 4191 m (4011 m TVD) in the Permian Zechstein Group.Well 7/12-3A penetrated the reservoir at 3638.5 (3506.8 m TVD). The cores showed oil staining, cut and fluorescence. Wire line logs and testing showed this to be immovable oil, and indicated an oil water transition zone to a depth of 3693.5. (3555.3 m TVD). One hundred and eighty-nine meters of Ula Formation reservoir were encountered representing a true thickness of 168.9 m, and a net to gross ratio of 0.83 assuming a 10% porosity cut off on the computer-processed log.Seven full hole cores were cut from 3642.0 to 3730.0 m. RFT fluid samples were taken at 3675.5 m (salt water and mud filtrate) and 3688.5 m (salt water with traces of gas and oil/oil-water emulsion).The well was permanently abandoned on 6 September 1977 as a dry well with shows.TestingDST 1 tested the interval 3771.0 to 3715.5m. The test flowed 192 m3 saline formation water /day through a 32/64 choke. The DST temperature was 146.7 °C.DST 2 teste the interval 3680.0 to 3669.5 m. The test flowed 509 m3 saline formation water with trace oil /day through a 32/64 choke. The DST temperature was 145.6 °C. -
Cuttings at the Norwegian Offshore Directorate
Cuttings at the Norwegian Offshore Directorate Cuttings available for sampling?NOCuttings at the Norwegian Offshore Directorate Cutting sample, top depth [m]Cutting samples, bottom depth [m]1730.004114.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13642.53660.0[m ]23660.03678.3[m ]33678.33692.2[m ]43692.23697.6[m ]53697.63698.0[m ]63700.03718.0[m ]73718.03730.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]85.5Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory3451.0[m]DCOD3460.0[m]DCOD3469.0[m]DCOD3481.0[m]DCOD3490.0[m]DCOD3499.0[m]DCOD3505.0[m]DCOD3511.0[m]DCOD3514.0[m]DCOD3520.0[m]DCOD3526.0[m]DCOD3529.0[m]DCOD3535.0[m]DCOD3541.0[m]DCOD3544.0[m]DCOD3550.0[m]DCOD3556.0[m]DCOD3559.0[m]DCOD3571.0[m]DCOD3580.0[m]DCOD3589.0[m]DCOD3601.0[m]DCOD -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit9615652655265526922731276228262826294731953261326135143514356036383638382739294095 -
Geochemical information
Geochemical information 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]pdf2.32pdf7.06pdf13.26 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0377137160.02.0367336620.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.02.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.02.0 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL16002500CBL16002500CBL VDL GR CCL33954105CST32603585CST36054125DLL RXO GR SP CAL35993827FDC CNL GR37734130FDC CNL GR CAL35993827ISF BHC GR SP16813586ISF BHC GR SP35994016ISF BHC GR SP35993825ISF BHC GR SP37664188RFT36264080RFT36503897RFT36750RFT36880TEMP16501979WST17204188 -
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 typeCONDUCTOR30169.036174.00.00SURF.COND.20466.026470.00.00INTERM.13 3/81679.017 1/21686.00.00INTERM.9 5/83601.012 1/23612.00.00OPEN HOLE4190.08 1/24190.00.00 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured17201.45waterbased20481.46waterbased28381.45waterbased33461.45waterbased36121.46waterbased -
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]pdf0.22