30/9-1
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General information
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Wellbore history
GeneralWell 30/9-1 was drilled on the southeast part of the Oseberg fault block (Alpha structure) in the North Sea. The Alpha structure is an eastward tilted fault block that contains proven reserves of oil and gas in the Middle Jurassic Brent Group sandstone reservoir. The primary objective of the well was to establish the oil/water contact in this part of the structure. The well was planned to be drilled to a total depth of 2850 m, approximately 100 m into the Dunlin Group.Operations and resultsAppraisal well 30/9-1 was spudded with the semi-submersible installation Treasure Seeker on 24 October 1982 and drilled to TD at 2895 m in the Early Jurassic Drake Formation. No significant problem was encountered in the operations. The well was drilled with seawater/hi-vis pills and pre-hydrated bentonite down to 969 m, with KCl/Drispac mud from 969 m to 2515 m, and with KCl/polysal mud from 2515 m to TD.The Brent Group was found hydrocarbon bearing from 2685 m down to 2738 m where the free water level was established. This interval comprises the whole of the Ness Formation and the uppermost 3 m of the Etive Formation. Net pay in the interval was 10.5 m. Poor oil shows were recorded on limestone cuttings in the interval 2281 to 2232 m in the uppermost Shetland Group. Good oil shows were recorded through the oil column of the reservoir. Below the contact at 2738 m, shows became weaker and patchy down to 2778 m. Below this depth only some weak shows on claystone from three sidewall cores in the interval 2872 m to 2895 m were reported.Seven conventional cores were cut from 2682 m at the top of the Ness formation to 2784.9 m, into the Dunlin Group shales. RFT fluid samples were taken at 2690.5 m (oil, gas, water, and filtrate), 2732.2 m (water and filtrate with small amounts of oil and gas), 2737.5 m (water and filtrate with trace oil and gas), and at 3782.2 m (water and filtrate with small amounts of oil and gas).The well was permanently abandoned on 29 January 1983 as an oil appraisal well.TestingThree drill stem tests were performed in the Brent Group.DST l (2743-2761 m) in the upper part of the Etive Formation is a combined water production/injection test. It produced 200 m3/day of water through a 44/64" choke. The first injection rate was 134 m3/day of water and the second injection rate amounted to 1170.4 m3/day) of water. Maximum temperature measured at 2740.5 m was 105.1 °C.DST 2 (2727 -2733 m) at the very base of the Ness Formation flowed 325 Sm3/day oil with 36507 Sm3/day of associated gas with a gravity of 0.780 (air = 1). Choke size was 28/64". The GOR was 112 Sm3/Sm3, the oil gravity was 32.2° API, and the gas gravity was 0.780 (air = 1). Maximum temperature measured at 2714.3 m was 106.6 °C.DST 3 (2689 – 2692 m) in the uppermost part of the Ness Formation tested 375 Sm3/day of oil and 39620 Sm3/day of gas through a 28/64" choke. The GOR was 106 Sm3/Sm3, the oil gravity was 34.9°API and the gas gravity 0.724 (air = 1). Maximum temperature measured at 2678.9 m was 105.7 °C. -
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]250.002895.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12681.82699.0[m ]22700.02707.0[m ]32708.52713.2[m ]42714.02730.5[m ]52737.32749.9[m ]62750.02768.0[m ]72768.02784.8[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]92.8Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
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 availableDSTDST2A2727.002733.0015.01.1983 - 00:00YESDSTDST32689.002692.0021.01.1983 - 00:00YES -
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 typeCONDUCTOR30217.036220.00.00LOTSURF.COND.20951.026969.01.64LOTINTERM.13 3/82498.017 1/22515.01.70LOTINTERM.9 5/82878.012 1/42895.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.02743276117.42.02727273311.13.02689269211.1Drill 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]1.02.0325370000.8640.7801123.0375400000.8500.724105 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL13002485CST17202514CST25052895CST25202885DLL MSFL MLL24952870HDT19002514HDT SHDT24952897ISF LSS219965ISF LSS MSFL9512512ISF LSS MSFL EPT24952895ISF LSS NGT24952897LDT CNL9512507LDT CNL NGT EPT24952893RFT25702881RFT27290RFT27322737RFT27370VELOCITY6482893 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit131645880198919892072215822702281241524252425247026852685273527832783 -
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]pdf4.45pdf23.78 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2601.05waterbased5601.10waterbased13001.32waterbased17301.44waterbased20801.46waterbased22601.48waterbased25601.24waterbased -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory330.0[m]DCRRI530.0[m]DCRRI730.0[m]DCRRI930.0[m]DCRRI1130.0[m]DCRRI1330.0[m]DCRRI1510.0[m]DCGEOCH1530.0[m]DCRRI1540.0[m]DCGEOCH1570.0[m]DCGEOCH1600.0[m]DCGEOCH1630.0[m]DCGEOCH1666.0[m]DCGEOCH1690.0[m]DCGEOCH1720.0[m]DCGEOCH1730.0[m]DCRRI1750.0[m]DCGEOCH1780.0[m]DCGEOCH1810.0[m]DCGEOCH1840.0[m]DCGEOCH1870.0[m]DCGEOCH1900.0[m]DCGEOCH1915.0[m]DCRRI1930.0[m]DCGEOCH1960.0[m]DCGEOCH1990.0[m]DCGEOCH2020.0[m]DCGEOCH2050.0[m]DCGEOCH2080.0[m]DCGEOCH2110.0[m]DCGEOCH2115.0[m]DCRRI2140.0[m]DCGEOCH2170.0[m]DCGEOCH2200.0[m]DCGEOCH2215.0[m]DCRRI2230.0[m]DCGEOCH2260.0[m]DCGEOCH2280.0[m]DCGEOCH2290.0[m]DCGEOCH2320.0[m]DCGEOCH2406.0[m]SWCRRI2415.0[m]SWCRRI2422.5[m]SWCRRI2433.0[m]SWCRRI2452.0[m]SWCRRI2465.0[m]SWCRRI2477.0[m]SWCRRI2485.0[m]SWCRRI2494.0[m]SWCRRI2505.0[m]SWCRRI2514.0[m]SWCRRI2528.0[m]SWCRRI2540.0[m]SWCRRI2560.0[m]SWCRRI2569.0[m]SWCRRI2580.0[m]SWCRRI2592.0[m]SWCRRI2605.0[m]SWCRRI2615.0[m]SWCRRI2624.0[m]SWCRRI2635.0[m]SWCRRI2649.0[m]SWCRRI2659.0[m]SWCRRI2672.5[m]SWCRRI2682.0[m]SWCRRI2693.1[m]CRRI2706.8[m]CRRI2739.7[m]CRRI2786.6[m]CRRI2790.0[m]DCRRI2795.0[m]SWCRRI2811.0[m]SWCRRI2837.0[m]SWCRRI2850.0[m]SWCRRI2860.0[m]SWCRRI2872.0[m]SWCRRI2880.0[m]DCRRI2885.0[m]SWCRRI2895.0[m]SWCRRI