2/7-27 S
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General information
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Wellbore history
GeneralWell 2/7-27 S was drilled on the Embla structure in the southern North Sea. The objective was to drill to replace the abandoned 2/7-23 S well as a production well in the Embla reservoir. Well 2/7-27 S would thus be drilled as close as possible to the 2/7-23 S well path and to the same bottom hole location. By this it was anticipated that the extensive core data recovered in the 2/7-23 S would be applicable to the production data to be gained from the 2/7-27 S. The 2/7-23 S had earlier confirmed the presence of hydrocarbon bearing sandstones originally discovered in the 2/7-9 (1974), and later tested in the 2/7-20 (1988) and 2/7-21 S (1989) wells, but was abandoned before well testing could be performed.Operations and resultsAppraisal well 2/7-27 S was spudded with the semi-submersible installation West Delta on 9 November 1991 and drilled to TD at 4801 m (4452 m TVD) in pre-Jurassic rocks. It was drilled deviated from a fifteen slot production template located at the site of the planned Embla production facilities. Drilling problems with stuck pipe were encountered in the 12 1/4" hole section at 3470 m, forcing a technical sidetrack from 2972.7 m. Unlike previous Embla wells, the 2/7-27S was drilled using water based mud throughout. It was drilled with seawater and hi-vis pills down to 573 m, with KCl/polymer mud from 573 m to 3791 m, with Baranex-Thermathin mud from 3791 m to 4500 m, and with a Thermadrill/Baranex high temperature mud system from 4500 m to TD.The 2/7-27 S well encountered top Mandal Formation at 4476 m and top pre-Jurassic reservoir at 4483.3 m (4177.6 m TVD) with the same reservoir stratigraphy as the 2/7-23S. However, although the wells are only 46.5 m apart at the Base Cretaceous Unconformity, this surface was penetrated 28 m TVD deeper in the 2/7-27 S. Log correlation and seismic interpretation suggest the presence of a fault between (in the vicinity of) the two wells, but the evidence is incomplete. The pre-Jurassic reservoir was hydrocarbon bearing as in well 2/7-23 S.One core was cut in each of the Ekofisk and Tor Formation and two consecutive cores were cut in the pre-Jurassic reservoir section. A segregated RFT sample was taken at 4488.5 m. It contained 100% mud filtrate.The well was suspended suitable for later re-entry and tie back as a production well. The well was completed on 17 June 1992. On 2 March 1993 it was re-entered and re-classified to development well.TestingA single DST test where performed over the pre-Jurassic reservoir from 4483.6 - 4740.9 m (4177.9 - 4399.5 m TVD). At the end of the main flow the well produced 582 Sm3 oil and 180400 Sm3 gas /day through a 20/64" choke. The GOR was 309 Sm3/Sm3 and the oil gravity was 45 deg API. The H2S content was 25 up to ppm (peak) and the CO2 content was 6%. With a 40/64" choke the GOR was 265 Sm3/Sm3. The maximum bottom hole temperature recorded in the main flow by the HRS Gauge at 4142.2 m (3894.9 m TVD) was 160 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]3855.504800.60 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom110410.010462.0[ft ]210715.010745.0[ft ]315039.015056.0[ft ]415056.015075.6[ft ]Cores at the Norwegian Offshore Directorate Total core sample length [m]36.1Cores 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 availableDSTDST14484.804742.1001.06.1992 - 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 typeCONDUCTOR30156.036157.00.00LOTINTERM.20570.026572.01.92LOTINTERM.13 3/82139.017 1/22140.02.00LOTINTERM.9 7/84285.012 1/44286.01.80LOTLINER74797.08 1/24800.02.18LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.0474144847.9Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.05821804000.8000.800309 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BGL GR30744261CBL VDL GR CCL931910CBL VDL GR CCL19843039CBL VDL GR CCL41824678DIL MSFLGR42884799DLL MSFL BHC GR21373166DLL MSFL BHC GR30744297FMS GR00LDL CNL GR21373109LDL CNL GR44734807MWD- GR RES DIR5504785RFT GR00SDT NGT44664803 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1001600300730073027308331403167316732553523416141704238423842874333436244764483 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf1.60pdf5.95pdf1.08pdf1.71 -
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]pdf2.67pdf51.20pdf60.60pdf18.11 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1601.43WATER BASED5701.04WATER BASED5731.04WATER BASED5791.5613.0WATER BASED10331.3324.0OIL BASED19191.7620.0WATER BASED19791.8726.0WATER BASED28271.8752.0WATER BASED28391.8753.0WATER BASED28431.8743.0WATER BASED30081.8747.0WATER BASED30401.8720.0WATER BASED30781.7326.0WATER BASED31461.7427.0WATER BASED31641.7124.0WATER BASED31701.8742.0WATER BASED31941.7129.0WATER BASED32001.8744.0WATER BASED32291.7539.0WATER BASED32961.8730.0WATER BASED33751.5930.0WATER BASED33751.5930.0WATER BASED33751.5929.0WATER BASED33751.5930.0WATER BASED33751.5930.0WATER BASED33911.8734.0WATER BASED34391.8734.0WATER BASED34471.8732.0WATER BASED34711.8629.0WATER BASED34731.5733.0WATER BASED35361.5635.0WATER BASED36751.5635.0WATER BASED36821.7526.0WATER BASED38901.5835.0WATER BASED39301.5810.0WATER BASED39951.6222.0WATER BASED40021.6323.0WATER BASED40081.7129.0WATER BASED40142.1032.0WATER BASED40391.7529.0WATER BASED41061.6825.0WATER BASED41341.6832.0WATER BASED41681.6829.0WATER BASED41711.6827.0WATER BASED42431.6824.0WATER BASED42552.1021.0WATER BASED42871.7524.0WATER BASED43001.7522.0WATER BASED43232.0429.0WATER BASED44152.0625.0WATER BASED45002.0623.0WATER BASED45052.0623.0WATER BASED45392.0620.0WATER BASED45622.1025.0WATER BASED45892.1028.0WATER BASED46682.1030.0WATER BASED47752.1031.0WATER BASED47762.0626.0WATER BASED48012.0626.0WATER BASED48012.0627.0OIL BASED