35/1-1
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General information
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Wellbore history
GeneralThe objectives of drilling the Sturlason 35/1-1 well were to test the hydrocarbon potential of the Jurassic Cook and Statfjord Formations and the Triassic Lunde Formation in the Marflo Ridge structural complex located northeast of the Tampen Spur. The well location was designed to test a significant hydrocarbon column height that would potentially spill into additional fault blocks without leaving commercial reserves up dip. The location should further, if possible, evaluate Paleocene potential without compromising the Mesozoic target.Operations and resultsExploration well 35/1-1 was spudded with the semi-submersible installation Deepsea Bergen on 28 May 2002 and drilled to TD at 4540 m.Site survey and gravity coring showed that the shallow geology at the well site consists of soft, silty clay down to 16-18 meters below the seabed. A flat topography is interspersed by frequent pockmarks (seabed depressions). These pockmarks are up to 100 meters in diameter and up to 5 meters deep and are scattered throughout the survey area. The closest pockmark is 50 m south of the 35/1-1 location. Pockmarks are believed to have formed as a result of fluid or gas escape originating in or beneath the soft surface sediments.The well was drilled with seawater and bentonite sweeps down to 878 m, with KCl brine/Glydril from 878 m to 2245 m, and with Versaport oil based mud from 2245 m to TD No shallow high-pressured water pocket was encountered in the 35/1-1 drilling operation.No producible hydrocarbons were encountered in the well. The well did not encounter any potential reservoir in the Paleocene interval. All three potential reservoir intervals were evaluated by MWD/LWD log and open hole wire line data. In the 8 1/2" hole section sidewall cores were collected and one run was performed using Schlumbergers Modular Formation Dynamics Tester (MDT) for pressure measurements and fluid sampling. The MDT tool was configured with 2 x 1 gallon chambers and 6 x 450 cc bottles for pressurized samples. Fluid samples were collected at 4043.12 in the Cook Formation, and at 4471 m and 4322.27 in the Statfjord Formation. The CPI made from the wire line log data indicated the presence of small amounts of residual hydrocarbons. Additionally, the sidewall cores and MDT samples contained traces of hydrocarbons. However, geochemical analyses showed that only the MDT sample from the Cook Formation contained trace hydrocarbons that could represent migrated petroleum. The hydrocarbons in the other samples were from the oil-based mud. It should also be noted that the potassium in the KCL/Glycol mud system masked the natural gamma ray readings of the formation in the 17 1/2" section and affected the CDR resistivity resulting in a useless LWD log. Conventional cores were not cut not in this well.The well was permanently abandoned on 18 July 2002 as a dry hole.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]890.004540.00 -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1200.0[m]DCPETROSTR1210.0[m]DCPETROS1220.0[m]DCPETROS1230.0[m]DCPETROS1250.0[m]DCPETROS1260.0[m]DCPETROS1270.0[m]DCPETROS1280.0[m]DCPETROS1310.0[m]DCPETROS1320.0[m]DCPETROS1330.0[m]DCPETROS1340.0[m]DCPETROS1350.0[m]DCPETROS1360.0[m]DCPETROS1370.0[m]DCPETROS1380.0[m]DCPETROS1390.0[m]DCPETROS1400.0[m]DCPETROS1420.0[m]DCPETROS1430.0[m]DCPETROS1440.0[m]DCPETROS1450.0[m]DCPETROS1460.0[m]DCPETROS1470.0[m]DCPETROS1480.0[m]DCPETROS1490.0[m]DCPETROS1500.0[m]DCPETROS1510.0[m]DCPETROS1520.0[m]DCPETROS1530.0[m]DCPETROS1550.0[m]DCPETROS1560.0[m]DCPETROS1570.0[m]DCPETROS1580.0[m]DCPETROS1610.0[m]DCPETROS -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit431158120202020204220502147215321532280330137263736373637423742381338133970408741244180426444764476 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.79 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf0.69 -
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].pdf3.83.PDF3.22 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]GR HDIL XMAC ZDL CN TTRM4052238GR HDIL XMAC ZDL CN TTRM21503830GR HDIL XMAC ZDL CN TTRM36454531MDT GR SAMPLES44890MSCT45100MWD - CDR DIR503878MWD - CDR DIR8782245MWD - CDR DIR38344540MWD CDR DIR22453834 -
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 typeCONDUCTOR30503.036503.00.00LOTINTERM.20872.026878.00.00LOTINTERM.13 3/82239.017 1/22245.01.65LOTINTERM.9 5/83826.012 1/43834.01.75LOTOPEN HOLE4540.08 1/24540.02.15LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4310.00SPUD MUD6720.0034.0VERSAPORT6780.00SEAWATER8630.0033.0VERSAPORT8780.12SPUD MUD16751.3418.0KCL/POLYMER22450.0032.0VERSAPORT26781.5039.0VERSAPORT34521.5236.0VERSAPORT38341.6132.0VERSAPORT39500.0036.0VERSAPORT41290.0035.0VERSAPORT45160.0049.0VERSAPORT45400.0048.0VERSAPORT -
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