25/7-4 S
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General information
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Wellbore history
GeneralBlock 25/7 is situated in the South Viking Graben on the western side of the Utsira High, a basement high that tilts slightly towards the east. The South Viking Graben has an asymmetrical profile bounded in the west by the Brea/Crawford Fault Zone and the Utsira High to the east. The Jotun Field is sitting on a basement terrace stepping up to the Utsira High from the Graben area. Well 25/7-1 drilled in 1986 for a Jurassic target encountered oil shows in thin ratty sands in the Paleocene Hermod Formation.Exploration well 25/7-4 S was drilled to test the 25/7 Hermod South prospect, a stratigraphic trap comprising of channelised basin floor sandstones of the Paleocene Hermod Formation. The primary objectives of the well were to test the presence of hydrocarbons in the Hermod South prospect and to establish hydrocarbon type(s) and fluid contacts (if present). A secondary objective was to evaluate the Lower Tertiary interval by ensuring that the well penetrates into the Cretaceous.Operations and resultsExploration well 25/7-4 S was spudded with the semi-submersible installation "Maersk Jutlander" on 2 June 1997 and drilled to a total depth of 2560 m in the Late Cretaceous Tor Formation. Operations went without problems within the AFE time budget. The well was drilled with seawater and hi-vis pills down to 1195 m and with KCl / Glycol mud from 1195 m to TD. Good quality Hermod sands were encountered at 2018 m (1987 m TVD SS). Also the Heimdal and Ty Formation sands were present. However, no indications of hydrocarbons were found.No conventional core was cut in and no fluid samples were taken. The well was permanently abandoned as a dry well on 21 June 1997.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]1200.002560.00 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1200.0[m]DCRRI1230.0[m]DCRRI1250.0[m]DCRRI1270.0[m]DCRRI1290.0[m]DCRRI1310.0[m]DCRRI1330.0[m]DCRRI1370.0[m]DCRRI1380.0[m]DCRRI1400.0[m]DCRRI1420.0[m]DCRRI1430.0[m]DCRRI1992.0[m]SWCRRI2003.0[m]SWCRRI2007.0[m]SWCRRI2013.0[m]DCRRI2017.0[m]SWCRRI2069.0[m]DCRRI2105.0[m]SWCRRI2126.0[m]SWCRRI2142.0[m]SWCRRI2151.0[m]SWCRRI2159.0[m]SWCRRI2163.0[m]SWCRRI2172.0[m]SWCRRI2186.0[m]SWCRRI2211.0[m]SWCRRI2218.0[m]SWCRRI2236.0[m]SWCRRI -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit14949071671610631904190420022018212121762371251225122550 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.32 -
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]pdf2.04pdf39.80 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CST19872236DSI DIT GR19322546MWD - DIR GR SN2311190MWD - DIR GR SN11901940MWD - DIR GR SN DEN NEU19402560VSP GR19322546 -
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 typeCONDUCTOR30226.036226.00.00LOTSURF.COND.13 3/81188.017 1/41190.01.90LOTINTERM.9 5/81931.012 1/41931.01.59LOTOPEN HOLE2560.08 1/22560.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1491.00SPUD MUD2221.00SPUD MUD5361.07SPUD MUD11881.20SPUD MUD11981.4542.0KCL/GLYCOL/GEM12001.07SPUD MUD12241.4539.0KCL/GLYCOL/GEM14521.3220.0KCL/GLYCOL/GEM19401.2015.0KCL/POLYMER22801.2011.0KCL/POLYMER25601.2112.0KCL/POLYMER