35/3-1
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General information
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Wellbore history
The exploratory well, 35/3-1, was drilled on block 35/3 in the northern Norwegian North Sea, approximately 65 km west of Måløy in western Norway. The location is east of the Norwegian Trench. The general objective was to test the total stratigraphical sequence down to pre-Jurassic strata. Within the sequence, sand development was predicted for the Lower Cretaceous and the Early Jurassic, with a possibility for minor sands in Middle-Late Jurassic. The well should penetrate two seismic reflectors believed to represent top Early-pre Jurassic and basement, respectively. Planned TD was at 5250 m.Operations and resultsWildcat well 35/3-1 was spudded with the semi-submersible installation Deepsea Saga on 19 July 1976. The well was terminated at 4475 m in the Dunlin Group (Middle Jurassic, Bajocian age). This was not the planned TD, but due to high pressure the well was abandoned at this depth for safety reasons. Because of this the two deep seismic reflectors were not tested in this well. The well was drilled with seawater and salt water gel/Milben mud down to 982 m, with gypsum mud from 982 m to 2474 m, and with lignosulphonate mud from 2474 m to TD.A number of Tertiary sands not normally encountered in this part of the North Sea, were penetrated in this well. In the Early Jurassic, at 3805 m, a 215 m sequence of Agat Formation sandstone was penetrated. At 4145 m a 21 m sequence of Late Jurassic Intra Heather Formation sandstone was penetrated. Shows were encountered and described as follows:"The first traces of hydrocarbons were encountered in Early Cretaceous sand at 3865 m. The sand gave a poor show of dead oil with no direct fluorescence, but with slow, streaming, cream cut fluorescence. Similar shows were occasionally encountered over the interval 3865 - 3975 m, partly with a fast, streaming, white cut fluorescence. At 3900 m a relatively clean, fine to medium grained silica cemented sand showed light brown stain, traces of pale yellow fluorescence, and fast, streaming, white cut fluorescence. In the Jurassic, two sand beds around 4220 m had a fair gas show of 350,000 ppm C1, 35000 ppm C2, and 13000 ppm C3 as recorded in The Analyst's unit. The sand had no stain and no direct fluorescence, but showed some scattered white cut fluorescence. A dirty sand stringer at 4225 m showed 130000 ppm C1, 23000 ppm C2 and 9500 C3, with associated scattered white cut fluorescence. General background gas in the Jurassic was 1000 ppm total."Geochemical analyses showed oil maturity below ca 3200 m (%Ro > 0.5). Below ca 4100 m analyses showed abundant light hydrocarbons, indicating condensate/gas generation from Heather shales below this depth. These shales had 1.9% organic carbon on average, representing a massive source rock for condensate and gas. No conventional cores were cut and no fluid sample taken. Fifty-one sidewall cores were recovered from 2975 m to TD.The well was plugged and abandoned on 26 October as a well with shows.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]520.004475.00 -
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 typeCONDUCTOR30505.036507.00.00LOTSURF.COND.20969.026970.00.00LOTINTERM.13 3/82465.017 1/22466.01.77LOTINTERM.9 5/84180.012 1/44182.02.04LOTOPEN HOLE4475.08 1/24475.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BHC SONIC GR5032472CBL3214176CBL3252461FDC CNL GR41764471FDC GR5034182HDT00HDT24624471IES5032474ISF SONIC GR24614468MLL ML41764471VELOCITY3754470 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit33057474374383596511611204135013501358139214221556158015801720296233593387372537253805402041454145416644354435 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.56 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf1.62 -
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]pdf12.11pdf3.08 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured5100.00seawater8191.1068.058.0water based23061.1953.030.0water based26221.3146.018.0water based31391.3548.05.0water based42021.3746.05.0water based43131.8049.04.0water based -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory2530.0[m]DCRRI2545.0[m]DCRRI2560.0[m]DCRRI2575.0[m]DCRRI2590.0[m]DCRRI2605.0[m]DCRRI2617.0[m]DCRRI2635.0[m]DCRRI2650.0[m]DCRRI2665.0[m]DCRRI2680.0[m]DCRRI2695.0[m]DCRRI2710.0[m]DCRRI2725.0[m]DCRRI2740.0[m]DCRRI2755.0[m]DCRRI2770.0[m]DCRRI2785.0[m]DCRRI2800.0[m]DCRRI2815.0[m]DCRRI2830.0[m]DCRRI2845.0[m]DCRRI2860.0[m]DCRRI2875.0[m]DCRRI2890.0[m]DCRRI2905.0[m]DCRRI2920.0[m]DCRRI2935.0[m]DCRRI2950.0[m]DCRRI2965.0[m]DCRRI2980.0[m]DCRRI2995.0[m]DCRRI3010.0[m]DCRRI3025.0[m]DCRRI3037.0[m]DCRRI3055.0[m]DCRRI3070.0[m]DCRRI3085.0[m]DCRRI3100.0[m]DCRRI3115.0[m]DCRRI3130.0[m]DCRRI3145.0[m]DCRRI3160.0[m]DCRRI3175.0[m]DCRRI3190.0[m]DCRRI3205.0[m]DCRRI3220.0[m]DCRRI3235.0[m]DCRRI3250.0[m]DCRRI3265.0[m]DCRRI3280.0[m]DCRRI3295.0[m]DCRRI3310.0[m]DCRRI3325.0[m]DCRRI3340.0[m]DCRRI3355.0[m]DCRRI3370.0[m]DCRRI3385.0[m]DCRRI3400.0[m]DCRRI3415.0[m]DCRRI3430.0[m]DCRRI3460.0[m]DCRRI3475.0[m]DCRRI3490.0[m]DCRRI3505.0[m]DCRRI3520.0[m]DCRRI3535.0[m]DCRRI3550.0[m]DCRRI3565.0[m]DCRRI3595.0[m]DCRRI3615.0[m]DCRRI3630.0[m]DCRRI3645.0[m]DCRRI3690.0[m]DCRRI3720.0[m]DCRRI3750.0[m]DCRRI3780.0[m]DCRRI3810.0[m]DCRRI3837.0[m]DCRRI3870.0[m]DCRRI3900.0[m]DCRRI3930.0[m]DCRRI3960.0[m]DCRRI3990.0[m]DCRRI4020.0[m]DCRRI4050.0[m]DCRRI4080.0[m]DCRRI4110.0[m]DCRRI4140.0[m]DCRRI