34/10-2
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General information
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Wellbore history
GeneralWell 34/10-2 was drilled on the "Alpha closure" in the northern North Sea, ca 8 km south of the 34/10-1 Gullfaks discovery drilled three months earlier on the "Delta structure". The primary objective of 34/10-2 well was to test sandstones of the Middle Jurassic series. The secondary objectives were sandstones of the Paleocene and Early Jurassic series.Operations and resultsWildcat well 34/10-2 was spudded with the semi-submersible installation Ross Rig on 9 September 1978 and drilled to TD at 3729 m in the Late Triassic Lunde Formation. No significant problem was encountered during drilling, but close to15 days were spent as WOW due to severe weather conditions, and final logging at TD suffered from the weather. The well was drilled with spud mud down to 517 m, with gel/lignosulphonate mud from 517 m to 1723 m, and with gel/lignosulphonate/"ADF Chrome Lignite" mud from 1723 m to TD.Well 34/10-2 proved the presence of gas in sandstones of Middle Jurassic Brent Group and oil in sandstones of the Early Jurassic Statfjord Formation. The Brent Group was hydrocarbon bearing all through from top at 2944 m down to top Dunlin Group (Drake Formation) at 3124 m. A total of 109 m was net pay sandstone with average porosity 20.8% and average water saturation 13.8%. The gas/oil/water contact was not seen. The Statfjord Formation was oil bearing from 3325 m down to ca 3390 m based on the well logs. It contained 31.75 m of net pay oil bearing sandstone with average porosity 15.9% and average water saturation 21.6%.Shows started at 1640 m. These were described typically as gold yellow fluorescence and fast streaming milky cut on claystones with trace sandstone. These shows continued down to 1845 m. From there and down to top Brent reservoir level only occasional fluorescence in limestone was recorded. Below the OWC in the Statfjord Formation shows on sandstones were recorded down t a depth of 3500 m.A total of eight cores were cut; two in the Middle Jurassic Ness and Rannoch formations and six in the Early Jurassic Statfjord Formation. An attempt to run the RFT was made but failed, so no pressure points or fluid samples were taken on wire line.The well was suspended on 8 December 1978 as an oil and gas discovery well.TestingTesting was postponed to a later re-entry.Re-entryThe well was re-entered with the semi-submersible installation Ross Rig on 8 July 1979. The purpose was formation testing and to take fluid samplesNo significant problems occurred in the operationsNo new formation was drilled.The RFT was run on wire line and pressure points and fluid samples were taken. Fluid samples were taken at 2964.5 m, 3024 m, 3105 m, and at 3592 m. Based on the pressure data and DST the OWC in the Statfjord Formation was estimated to be at 3385 m.The well was permanently abandoned on 10 August 1979.TestingFive drill stem tests were performed in the well.DST 1 tested the interval 3385 - 3395 m in the Statfjord Formation. It produced pure water at rates declining from 700 m3 to 570 m3 /day through a 48/64" choke. The bottom hole maximum temperature in the main flow was 130.6 deg C.DST 2 tested the interval 3355 - 3365 m in the Statfjord Formation. The main flow was shut in too early due to a leak and was partly a failure. The production rate on a 48/64" choke was estimated tentatively to be ca 127 Sm3 oil and 19000 Sm3 gas/day with a GOR of 150 Sm3/Sm3. The oil gravity was 32.2 deg API and the gas gravity was 0.678 (air = 1). The bottom hole maximum temperature before shut-in was 128.9 deg C.DST 3 tested the interval 3335 - 3345 m in the Statfjord Formation. The first attempt was unsuccessful as the sand screen got plugged. The second attempt, DST 3 A, was run without sand screen. DST 3A produced on average 127 Sm3 oil and 19800 Sm3 gas /day through a 48/64" choke in the final flow. Ca 2% water cut was measured at goos neck. The GOR was ca 155 Sm3/Sm3, the oil gravity was 32 deg API and the gas gravity was 0.696 (air = 1). The bottom hole maximum temperature in the main flow was 125 deg C.DST 4 tested the interval 3110 - 3115 in the Rannoch Formation. During the final flow the well was produced at a metered gas rate of about 96300 Sm3 /day on a 20/64" choke. Tank measurement indicated a condensate rate of about 12 Sm3/day and a water rate of about 6 m3/day. The gas/condensate ratio was ca 8000 Sm3/Sm3, the oil gravity was 48 deg API, and the gas gravity was 0.652 (air = 1). The bottom hole maximum temperature was 110 deg C.DST 5 tested the interval 3017 - 3022 m in the Ness Formation. The well produced in the final flow through 2 x 20/64" choke in parallel 733400 Sm3 gas/day with a condensate rate in the range 175 - 240 Sm3 /day and a corresponding gas/condensate ratio of 3100 - 4200 Sm3/Sm3. The oil gravity was 43 deg API and the gas gravity was 0.645 (air = 1). The bottom hole maximum temperature was 115 deg 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]710.003730.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13031.03041.2[m ]23103.03113.6[m ]33338.03345.2[m ]43345.23361.4[m ]53363.53366.3[m ]63366.63371.9[m ]73371.93382.4[m ]83382.43390.1[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]70.5Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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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 availableDSTTEST23353.003365.0022.07.1979 - 00:00YESDSTTEST33335.003345.0026.07.1979 - 08:00YESDSTTEST3A3335.000.0028.07.1979 - 00:00YESDSTTEST43110.003115.0002.08.1979 - 13:00YESDSTDST53018.003028.0005.08.1979 - 07:02YES -
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 typeCONDUCTOR30208.036208.00.00LOTSURF.COND.20508.026516.00.00LOTINTERM.13 3/81802.017 1/21810.00.00LOTINTERM.9 5/82799.012 1/42810.00.00LOTLINER73725.08 1/23730.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.03385339519.02.03355336519.03.03335334519.04.0311031157.95.0301730229.5Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.04.0002.01293.01.0001254.03.5001105.04.300115Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.02.0127190000.8650.6781503.0127198000.8650.6961554.012963000.8100.65280005.02387334000.8100.6453800 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL4001798CBL19912698DLL MSFL GR29003728FDC CNL GR CAL5083729HDT26993727HDT26993330ISF SON GR SP2083727NGS29233532VELOCITY8503720 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit15894596510951140116514121440152315751597163716651795179518582017201726252863286328672870288228822889294429443070308331243124317232003222332533253379349735403540 -
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]pdf0.10pdf0.55pdf0.46pdf15.95pdf15.95pdf206.39pdf0.29pdf2.85pdf0.51pdf0.99pdf2.09pdf2.43pdf38.25pdf0.18pdf4.75pdf1.03pdf0.94pdf1.10pdf6.59pdf3.12pdf0.10pdf7.36pdf0.13pdf0.33 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2101.0641.0spud mud5171.1323.035.0spud mud8671.2243.014.0waterbased18101.2748.021.0waterbased21281.5055.016.0waterbased26231.5253.017.0waterbased28701.6251.011.0waterbased32831.7052.08.0waterbased37301.7066.09.0waterbased -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory2891.0[m]DCGEOCH2903.0[m]DCGEOCH2909.0[m]DCGEOCH2921.0[m]DCGEOCH2930.0[m]DCGEOCH2945.0[m]DCGEOCH2954.0[m]DCGEOCH3031.0[m]CLAP3032.9[m]CLAP3033.8[m]CLAP3035.9[m]CLAP3037.2[m]CLAP3037.5[m]CLAP3039.6[m]CLAP3041.1[m]CLAP3340.2[m]COD3342.3[m]COD3352.9[m]COD3366.2[m]COD3375.5[m]COD3376.7[m]COD3382.4[m]COD3384.5[m]COD3385.5[m]COD3386.9[m]COD3387.6[m]COD3388.0[m]COD