25/4-5
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General information
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Wellbore history
GeneralWell 25/4-5 was drilled ca 1 km SW of the 25/4-1 Heimdal Discovery well. The primary objective was to test the Vestland Group and the Statfjord Formation on a down-thrown panel west of the high drilled by the 25/4-1 well, which found several hydrocarbon bearing Jurassic levels in addition to the main Heimdal Discovery. The secondary objective was to appraise the gas-bearing section in the Paleocene Heimdal Formation.Operations and resultsWildcat well 25/4-5 was spudded with the semi-submersible installation Dyvi Alpha on 26 June 1980 and drilled to TD at 4355 m in the Triassic Smith Bank Formation. Operations were interrupted by a strike that led to 4.5 days down time.The Heimdal reservoir was found at 2150 m with gas down to a GOC at 2172 m and a 7 m oil column down to the oil-water contact at 2179 m. Drill with 8 1/2" bit from 3600 m to 4198.5 m When running in hole in the 8 1/2" section the bit stuck at 4174. The hole was then backed off to 3891 m and a technical sidetrack was made from 3769 m.A 128 m thick Vestland Group was penetrated from 3692 m to 3820 m. The Hugin and Sleipner formations were found water bearing with residual hydrocarbons with the exception of a thin oil bearing interval from 3777.5 m to 3781.5 m. RFT sampling over this zone indicated a water gradient, but an RFT fluid sample recovered both oil (0.25 l) and gas (139 l).The Statfjord was encountered at 3949 m and was 178 m thick. It contained sandstones in the upper 50 m and in the interval from 4064 to 4098 m. The upper interval could be interpreted as hydrocarbon bearing. Direct fluorescence (yellow) and cuts (yellow -pale blue) were observed on the cores from this formation, and migrated hydrocarbons were also found by post-well organic geochemical analyses. Tests (DST and RFT) recovered only water.The triassic Group contained a 50 meters sandstone reservoir, which was drilled with good shows. The tests showed that the sandstones had to be considered as tight, producing only small volumes of water.Nine cores were cut between 2130 and 2235 m in the Lista and Heimdal Formations, 2 cores were cut between 3695 and 3730.7 m in the Hugin Formation, 4 cores were cut between 3954.5 m and 4014.6 m in the Statfjord Formation, and two cores were cut from 4140 m to 4158 m and 4183.5 m to 4198.5 m in the Skagerrak Formation. Wire line fluid samples (FIT and RFT) were taken at 3698 m (water without gas), 3779.2 m (139 l gas and 0.25 l oil), 3779.5 m (85 l gas and 2 l water), 4072 m (water without gas), 3996.8 m (water without gas), and at 4160 m (81 l gas and 10 l water).The well was permanently abandoned on 26 March 1981 as a gas and oil appraisal well.TestingThe Heimdal Formation was not tested. Three drill stem tests were conducted in the Jurassic and Triassic. DST 1 from 4154 m to 4176 m in the Triassic Skagerrak Formation did not produce any reservoir fluid to surface, even after acid treatment. Tight reservoir was concluded. DST2 from 3960 m to 3999 m in the middle Statfjord Formation produced water with gas bubbles at a rate of 19 Sm3/day. DST3 in the upper Statfjord Formation produced water with gas bubbles at a rate of 34 Sm3/day. -
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]211.004332.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12130.02146.0[m ]22148.02152.0[m ]32154.52158.0[m ]42158.02172.8[m ]52172.02180.4[m ]62181.02190.9[m ]72191.02199.6[m ]82200.02218.0[m ]92224.02232.0[m ]103695.03713.1[m ]113713.03730.8[m ]123954.53970.5[m ]133971.53984.0[m ]143985.03998.5[m ]153998.54014.5[m ]164183.54198.0[m ]174140.04158.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]217.5Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1950.0[m]DCRRI1960.0[m]DCRRI1970.0[m]DCRRI1990.0[m]DCRRI2010.0[m]DCRRI2033.0[m]DCRRI2060.0[m]DCRRI2080.0[m]DCRRI2100.0[m]DCRRI2120.0[m]DCRRI2130.0[m]DCRRI2140.0[m]DCRRI2150.0[m]DCRRI2160.0[m]DCRRI2166.0[m]DCRRI2238.0[m]DCRRI2266.0[m]DCRRI2290.0[m]DCRRI2310.0[m]DCRRI2356.0[m]DCRRI2378.0[m]DCRRI2404.0[m]DCRRI2428.0[m]DCRRI -
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 availableDSTTEST14154.004176.00WATER15.03.1981 - 00:00YESDSTDST24065.004088.00WATER09.03.1981 - 00:00YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1463874337758709259931090134313721998199820332090215023472550265926592960325833763379347934793507357435923592361936923692373038203949412741274207 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.83 -
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]pdf4.42pdf1.60 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0415441760.02.0406540880.03.0396939990.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.02.03.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.02.03.0 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BGT19502821BGT35943880BHC GR14002188CBL VDL GR4252817CBL VDL GR15503584DLL MSFL19502235DLL MSFL35944253FDC CNL GR8664355HDT19162814HDT19502821HDT35904355ISF BHC GR2674355LDT CNL19502821NGT19502820NGT35904355 -
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 typeCONDUCTOR30207.036297.60.00LOTSURF.COND.20866.026880.01.45LOTINTERM.13 3/82817.017 1/22822.01.72LOTINTERM.9 5/83590.012 1/43600.02.14LOTLINER74250.08 1/24355.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured23961.4030.020.0seawater24481.4030.020.0seawater40801.8246.016.0seawater43551.75seawater -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit3700.18[m ]3703.58[m ]3711.16[m ]3718.06[m ]3722.80[m ]3729.30[m ] -
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