Factpages Norwegian Offshore Directorate
Factpages Norwegian Offshore Directorate
Factpages Norwegian Offshore Directorate
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22.11.2024 - 09:09
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25/8-8 S

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  • General information
    General information
    Attribute Value
    Wellbore name
    Official name of wellbore based on Norwegian Offshore Directorate guidelines for designation of wells and wellbores.
    25/8-8 S
    Type
    Wellbore type. Legal values: EXPLORATION, DEVELOPMENT, OTHER (see 'Purpose' for more information)
    EXPLORATION
    Purpose
    Final classification of the wellbore.

    Legal values for exploration wellbores:
    WILDCAT, APPRAISAL, WILDCAT-CCS, APPRAISAL-CCS.

    Legal values for development wellbores:
    OBSERVATION, PRODUCTION, INJECTION, INJECTION-CCS, OBSERVATION-CCS.

    Legal values for other wellbores:
    SOIL DRILLING (drilling in connection with track surveys and other subsurface surveys to investigate the soil conditions prior to placement of facilities),
    SHALLOW GAS (drilling to investigate shallow gas before the first 'real' drilling on the location),
    PILOT (drilling to investigate the geology and fluid connectors for location of the main wellbore),
    SCIENTIFIC (drilling according to Law of Scientific research and exploration),
    STRATIGRAPHIC (driling according to Law of Petroleum activities §2-1).
    WILDCAT
    Status
    Status for the wellbore. Legal values are:

    BLOWOUT: A blowout has occurred in the well.
    CLOSED: A development wellbore that has been closed in a shorter or longer periode. Also applies to development wellbores where drilling is completed, but production/injection has not yet been reported.
    DRILLING: The well is in the drilling phase - can be active drilling, logging, testing or plugging,
    JUNKED: The drilling operation has been terminated due to technical problems.
    P&A: Exploration: The well is plugged and abandoned, and can not be reentered for further use. Development wells: The production/injection from/to the well is stopped and the well is plugged. The wellhead is removed or else made unavailable for further well operations.
    PLUGGED: The wellbore has been plugged, but the upper parts of the wellbore can be re-used. A sidetrack might be drilled at a later stage.
    PRODUCING: It was produced from the wellbore at the time of the operators last monthly report to the Norwegian Offshore Directorate.
    INJECTING: It was injected to the wellbore at the time of the operators last monthly report to the Norwegian Offshore Directorate.
    PREDRILLED: The upper part of the well has been drilled, usually as part of a batch-drilling campaign covering several wellbores.
    RE-CLASS TO DEV: Exploration wellbore that is reclassified to a development wellbore.
    RE-CLASS TO TEST: Exploration wellbore that is reclassified to test production.
    SUSPENDED: The drilling operation in the wellbore has been temporarily stopped. The current plan is to continue drilling later on.
    P&A
    Multilateral
    Indicator telling if the parent well is multilateral, meaning it has more than one branch radiating from the main borehole. Example of legal values: YES, NO. See also Norwegian Offshore Directorate guidelines for designation of wells and wellbores.
    NO
    Factmaps in new window
    Main area
    Name of the area on the Norwegian Continental Shelf where the wellbore is located. Legal values: BARENTS SEA, NORWEGIAN SEA, NORTH SEA.
    NORTH SEA
    Field
    Name of the field the wellbore is related to.
    Discovery
    Name of the discovery the wellbore is related to.
    Well name
    Official name of the parent well for the wellbore based on Norwegian Offshore Directorate guidelines for designation of wells and wellbores.
    25/8-8
    Production licence
    Official designation of the production licence the wellbore was drilled or planned to be drilled from ( well head posistion).
    Drilling operator
    Name of the licensee starting the drilling operation on behalf of the active production license (well head position). This will usually equal the operator of the production license.
    Esso Exploration and Production Norway A/S
    Drill permit
    The drilling permit number together with the version of the drilling permit as stated in the drilling permit granted by the Norwegian Offshore Directorate.
    823-L
    Drilling facility
    Norwegian Offshore Directorate's name of the facility which the wellbore was drilled from.
    Drilling days
    Number of days from wellbore entry to wellbore completion.
    34
    Entered date
    The date when he wellbore was spudded. For sidetracks: The date when new formation was drilled by kicking off from the mother-wellbore,
    22.08.1995
    Completed date
    Exploration wellbores from moveable facilities:
    For floating facilities - date when anchor handling is started. For jackups - date the jacking-down started. Exploration wellbores from fixed facilities and all development wellbores:
    Date when the wellbore is at total depth, and last casing, liner or screen is set. In case of immediate plugging of the wellbore, completed date equals the date the last plug i set in the wellbore.
    Date when the wellbore is at total depth, and last casing, liner or screen is set. In case of immediate plugging of the wellbore, completed date equals the date the last plug i set in the wellbore.
    24.09.1995
    Release date
    Date when raw data which has been reported to the authorities from the wellbore is not confidential any longer. Normally 2 years after finishing the drilling. May be earlier if the area of the production license is relinquished.
    24.09.1997
    Publication date
    Date quality control of the wellbore information was completed, so it can be published on the internet as a 'Well Data Summary Sheet' wellbore with more information available than other wellbores.
    29.08.2003
    Purpose - planned
    Pre-drill purpose of the wellbore. Legal values for exploration wellbores: WILDCAT, APPRAISAL, WILDCAT-CCS, APPRAISAL-CCS. Example of legal values for development wellbores: OBSERVATION, PRODUCTION, INJECTION.
    WILDCAT
    Content
    For exploration wellbores, status of discovery.

    Legal values:
    DRY, SHOWS (trace amounts of hydrocarbons), GAS, GAS/CONDENSATE, OIL or OIL/GAS.
    SHOWS (GAS SHOWS, OIL SHOWS or OIL/GAS SHOWS) are detected as fluorescent cut (organic extract), petroleum odour, or visual stain on cuttings or cores, or as increased gas reading on the mud-loggers gas detection equipment.
    Legal values for WILDCAT-CCS and APPRAISAL-CCS: WATER

    For development wellbores, type of produced/injected fluid.
    Legal values:
    WATER, CUTTINGS, NOT AVAILABLE, OIL, GAS/CONDENSATE, OIL/GAS, CO2, GAS, WATER/GAS, NOT APPLICABLE.
    OIL/GAS
    Discovery wellbore
    Indicator which tells if the wellbore made a new discovery. Legal values: YES, NO. Prior to press-release or other information regarding drilling results, the indicator will be “NO” as a default.
    YES
    1st level with HC, age
    Age of lithostratigraphic unit, 1st level, where hydrocarbons were encountered. Examples of legal values: CRETACEOUS, EARLY CRETACEOUS, LATE JURASSIC, EOCENE. See also Norwegian Offshore Directorate bulletins.
    PALEOCENE
    1st level with HC, formation
    Name of lithostartigraphic unit, 1st level, where hydrocarbons were encountered. Shown only for released wells. Examples of legal values: BASEMENT, COOK FM, EKOFISK FM, HEIMDAL FM, SANDNES FM, SOGNEFJORD FM, TARBERT FM, BRENT GP. See also Norwegian Offshore Directorate bulletins.
    HEIMDAL FM
    Kelly bushing elevation [m]
    Elevation of the rotary kelly bushing (RKB) above mean sea level.
    25.0
    Water depth [m]
    Depth in metres betweem mean sea level and sea floor.
    126.5
    Total depth (MD) [m RKB]
    Total measured length of wellbore from kelly bushing to total depth (driller's depth).
    2592.0
    Final vertical depth (TVD) [m RKB]
    Vertical elevation from total depth to kelly bushing. Shown only for released wells. Referred to as true vertical depth (TVD).
    2343.7
    Maximum inclination [°]
    Maximum deviation, in degrees, from a vertical well path.Shown only for released wells.
    35.5
    Oldest penetrated age
    Age (according to Geologic Time Scale 2004 by F. M. Gradstein, et al. (2004)) of the oldest penetrated formation. May differ from age at TD for example in deviated wellbores. Examples of legal values: CRETACEOUS, EARLY CRETACEOUS, LATE JURASSIC, EARLY PERMIAN, EARLY TRIASSIC, EOCENE.
    LATE JURASSIC
    Oldest penetrated formation
    Name of the oldest lithostratigraphic unit penetrated by the wellbore. Shown only for released wells. In most wellbores this is formation or group at total depth. May differ from formation or group at TD for example in wellbores drilled with high deviation or through faults. Examples of legal values: AMUNDSEN FM, BALDER FM, BASEMENT, BLODØKS FM, BRYNE FM, BURTON FM, COOK FM, DRAKE FM, DRAUPNE FM, EKOFISK FM, DUNLIN GP.
    DRAUPNE FM
    Geodetic datum
    Reference system for coordinates. Example of legal values: ED50.
    ED50
    NS degrees
    Geographic coordinate of the wellhead, north-south degrees.
    59° 25' 51.87'' N
    EW degrees
    Geographic coordinate of the wellhead, east-west degrees.
    2° 24' 18.73'' E
    NS UTM [m]
    Universal Transverse Mercator coordinate of the wellhead, north-south.
    6588357.70
    EW UTM [m]
    Universal Transverse Mercator coordinate of the wellhead, east-west.
    466254.24
    UTM zone
    Universal Transverse Mercator zone. Examples of legal values: 31, 32, 33, 34.
    31
    NPDID wellbore
    Norwegian Offshore Directorate's unique id for the wellbore.
    2646

  • Wellbore history
    General
    Well 25/8-8 S was drilled to test the Paleocene Heimdal Formation sandstones (Tau Prospect) located southeast of the Jotun Field and north east of the Balder Field on the east margin of the South Viking Graben. The well was planned with flexibility to be sidetracked into two other reservoir segments from the same 13 3/8" casing. The well proved oil in the target and two sidetracks were drilled. Well 25/8-8 A was the first sidetrack and the objective was to appraise the discovery in the primary well and to evaluate the sand quality in the eastern segment of the Tau Structure. Well 25/8-8 B was the second sidetrack and the objective was to appraise and evaluate resource potential in the western segment of the 25/8-8 S Discovery and to confirm oil-water and possibly gas-oil contacts.
    Operations and results
    Exploration well 25/8-8 S was spudded with the semi-submersible installation "Vildkat Explorer" on 22 August 1995 and drilled deviated to TD at 2592 m (2343.7 m TVD SS) in the Late Jurassic Draupne Formation. The well was drilled to 1058 m with seawater and high viscosity gel pills. From 1058 m to TD the well was drilled using an oil-based mud, "Safemul". MWD-GR-Res was used during drilling. MWD-resistivity failed at 872 m and the hole was drilled to 1058 m without resistivity log. No shallow gas was observed. The 13 3/8" casing was set at 1046.5 m.
    When the second run with the MDT was done, the MDT cable became stuck. The cable broke at the casing shoe, leaving the tool and about 1000 m of cable in the hole. A fishing job was performed to get the tool and cable out. The fishing job was successful and the rest of the logging program was completed.
    The target Heimdal Formation was penetrated at 2236 m and was found hydrocarbon bearing. A GOC is indicated within the interval 2244.9-2252.0 m (2057.0-2063.0 m TVD SS) based on ELAN log analysis, pressure analysis and geochemical analyses. Available well data indicate an OWC at 2283.5 m (2089.3 m TVD SS) with oil saturation up to 5 m TVD deeper. Three 27-metre cores were cut in the Lista and Heimdal Formations in the interval 2228 m to 2309 m. Fluid samples were taken in the first MDT run at 2244.2 m (gas) and 2260.0 m (oil). After testing the well was plugged back to the 13 3/8" casing and the casing pulled to get ready for the first sidetrack, 25/8-8 A.
    Sidetrack 25/8-8 A was kicked off from below the 13 3/8" casing shoe at 1080 m on 26 September 1995 and drilled to a TD of 2601.3 m (2158.1 m TVD SS) in the Early Paleocene Ty Formation. The wellbore was drilled with "Safemul" oil based mud from kick off to TD. Based on MDT pressures and extensive MDT sampling 25/8-8 A confirmed oil and gas in the Heimdal Formation with a GOC estimated at 2057.8 m TVD SS and an OWC estimated at 2094.5 m TVD SS. It also proved the amount of sand and reservoir quality decrease eastwards from the original 25/8-8 S well location. Borehole 25/8-8 A was not drill stem tested. Four conventional cores were cut in the Lista and Heimdal Formations in the interval 2414 m to 2522 m. MDT fluid samples were recovered from the Heimdal Formation at depths 2430 m (gas),& 2445.6 m (gas), 2453 m (oil), and 2457.8 m (oil). Post-well organic geochemical analyses indicated some "diesel" contamination in the oil samples. After logging sidetrack 25/8-8A was plugged and abandoned as an oil and gas appraisal well.
    The second sidetrack, 25/8-8 B, was kicked off from 1080 m on 11 October 1995 and drilled to a total depth of 2510 m (2152 m TVD SS) in the Paleocene Lista Formation. The well was drilled with oil-based mud from kick off to TD.
    Pressures and extensive MDT sampling confirmed the oil and water gradients and defined the OWC in the Heimdal Formation. The oil water contact was found at 2428.9 m (2094.7 m TVD SS). The well was not drill stem tested. Three cores were cut in the Lista and Heimdal Formations from 2375 m to 2441 m. After logging sidetrack 25/8-8 B was plugged back and abandoned as an oil and gas appraisal well.
    The primary wellbore 25/8-8 S was permanently abandoned on October 24, 1995 as an oil and gas discovery, named the 25/8-8 S Jotun Discovery.
    Testing
    Well 25/8-8 S was drill stem tested. The main interval 2258 m - 2267 m produced a little sand (1%) at 795 Sm3/day and was chocked back to 628 Sm3/day for the main flow. GOR was 70 Sm3/Sm3.& After the main flow, a lower interval 2275-2279 m was perforated with tubing conveyed gun and the two intervals were flowed co-mingled at 1065 Sm3/day with traces of sand. GOR was 70 Sm3/Sm3.

  • Cuttings at the Norwegian Offshore Directorate
    Cuttings at the Norwegian Offshore Directorate
    Cuttings available for sampling?
    YES
    Cuttings at the Norwegian Offshore Directorate
    Cutting sample, top depth [m]
    Cutting samples, bottom depth [m]
    1070.00
    2590.00

  • Cores at the Norwegian Offshore Directorate
    Cores at the Norwegian Offshore Directorate
    Core sample number
    Core sample - top depth
    Core sample - bottom depth
    Core sample depth - uom
    1
    2228.0
    2252.8
    [m ]
    2
    2255.0
    2282.0
    [m ]
    3
    2282.0
    2309.0
    [m ]
    Cores at the Norwegian Offshore Directorate
    Total core sample length [m]
    78.7
    Cores at the Norwegian Offshore Directorate
    Cores available for sampling?
    YES

  • Core photos
    Core photos
    Core photo at depth: 2228-2233m
    Core photo at depth: 2233-2238m
    Core photo at depth: 2238-2243m
    Core photo at depth: 2243-2248m
    Core photo at depth: 2248-2252m
    2228-2233m
    2233-2238m
    2238-2243m
    2243-2248m
    2248-2252m
    Core photo at depth: 2255-2260m
    Core photo at depth: 2260-2265m
    Core photo at depth: 2265-2270m
    Core photo at depth: 2270-2275m
    Core photo at depth: 2275-2280m
    2255-2260m
    2260-2265m
    2265-2270m
    2270-2275m
    2275-2280m
    Core photo at depth: 2280-2282m
    Core photo at depth: 2282-2287m
    Core photo at depth: 2287-2292m
    Core photo at depth: 2292-2297m
    Core photo at depth: 2297-2302m
    2280-2282m
    2282-2287m
    2287-2292m
    2292-2297m
    2297-2302m
    Core photo at depth: 2302-2307m
    Core photo at depth: 2307-2309m
    Core photo at depth:  
    Core photo at depth:  
    Core photo at depth:  
    2302-2307m
    2307-2309m

  • Casing and leak–off tests
    Casing and leak–off tests
    Casing type
    Casing diam.
    [inch]
    Casing depth
    [m]
    Hole diam.
    [inch]
    Hole depth
    [m]
    LOT/FIT mud eqv.
    [g/cm3]
    Formation test type
    CONDUCTOR
    30
    211.0
    36
    212.0
    0.00
    LOT
    SURF.COND.
    13 3/8
    1046.0
    17 1/2
    1046.0
    0.00
    LOT
    LINER
    7
    2592.0
    8 1/2
    2592.0
    0.00
    LOT

  • Drill stem tests (DST)
    Drill stem tests (DST)
    Test number
    From depth MD
    [m]
    To depth MD
    [m]
    Choke size
    [mm]
    1.0
    2258
    2267
    50.0
    Drill stem tests (DST)
    Test number
    Final shut-in pressure
    [MPa]
    Final flow pressure
    [MPa]
    Bottom hole pressure
    [MPa]
    Downhole temperature
    [°C]
    1.0
    3.600
    Drill stem tests (DST)
    Test number
    Oil
    [Sm3/day]
    Gas
    [Sm3/day]
    Oil density
    [g/cm3]
    Gas grav. rel.air
    GOR
    [m3/m3]
    1.0
    1067
    75900
    0.850
    0.730
    71

  • Logs
    Logs
    Log type
    Log top depth [m]
    Log bottom depth [m]
    AIT IPL EPT GR
    1046
    2584
    CBL
    1500
    2539
    CST GR
    1175
    2555
    DSI GR
    1046
    2285
    DSI UBI GR
    2125
    2587
    MDT GR
    2237
    2260
    MDT GR
    2238
    2238
    MDT GR
    2238
    2463
    MWD - GR RES DIR
    206
    2583
    PLT
    2256
    2300
    VSP
    480
    2505

  • Lithostratigraphy

  • Geochemical information
    Geochemical information
    Document name
    Document format
    Document size [MB]
    pdf
    1.95
    pdf
    1.64

  • 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 name
    Document format
    Document size [MB]
    pdf
    65.30

  • Drilling mud
    Drilling mud
    Depth MD [m]
    Mud weight [g/cm3]
    Visc. [mPa.s]
    Yield point [Pa]
    Mud type
    Date measured
    157
    1.05
    DUMMY
    1058
    1.05
    DUMMY
    1175
    1.43
    47.0
    OIL BASED
    2115
    1.43
    44.0
    OIL BASED
    2229
    1.43
    44.0
    OIL BASED
    2295
    1.45
    41.0
    OIL BASED
    2460
    1.43
    41.0
    OIL BASED
    2506
    1.43
    40.0
    OIL BASED
    2543
    1.08
    DUMMY
    2544
    1.43
    39.0
    OIL BASED
    2592
    1.08
    DUMMY

  • Palynological slides at the Norwegian Offshore Directorate
    Palynological slides at the Norwegian Offshore Directorate
    Sample depth
    Depth unit
    Sample type
    Laboratory
    1110.0
    [m]
    DC
    STRAT
    1130.0
    [m]
    DC
    STRAT
    1150.0
    [m]
    DC
    STRAT
    1175.0
    [m]
    SWC
    STRAT
    1190.0
    [m]
    DC
    STRAT
    1240.0
    [m]
    DC
    STRAT
    1260.0
    [m]
    DC
    STRAT
    1280.0
    [m]
    DC
    STRAT
    1335.0
    [m]
    SWC
    STRAT
    1362.0
    [m]
    SWC
    STRAT
    1400.0
    [m]
    SWC
    STRAT
    1440.0
    [m]
    DC
    STRAT
    1480.0
    [m]
    SWC
    STRAT
    1510.0
    [m]
    DC
    STRAT
    1540.0
    [m]
    DC
    STRAT
    1580.0
    [m]
    DC
    STRAT
    1610.0
    [m]
    DC
    STRAT
    1625.0
    [m]
    SWC
    STRAT
    1650.0
    [m]
    DC
    STRAT
    1680.0
    [m]
    DC
    STRAT
    1730.0
    [m]
    DC
    STRAT
    1760.0
    [m]
    DC
    STRAT
    1779.0
    [m]
    SWC
    STRAT
    1820.0
    [m]
    DC
    STRAT
    1853.0
    [m]
    SWC
    STRAT
    1880.0
    [m]
    DC
    STRAT
    1920.0
    [m]
    DC
    STRAT
    1950.0
    [m]
    DC
    STRAT
    1968.0
    [m]
    SWC
    STRAT
    1990.0
    [m]
    DC
    STRAT
    2026.0
    [m]
    SWC
    STRAT
    2057.0
    [m]
    SWC
    STRAT
    2062.0
    [m]
    SWC
    STRAT
    2080.0
    [m]
    SWC
    STRAT
    2080.0
    [m]
    SWC
    STRAT
    2095.0
    [m]
    SWC
    STRAT
    2108.0
    [m]
    SWC
    STRAT
    2120.0
    [m]
    DC
    STRAT
    2130.0
    [m]
    DC
    STRAT
    2139.0
    [m]
    SWC
    STRAT
    2140.0
    [m]
    DC
    STRAT
    2150.0
    [m]
    DC
    STRAT
    2155.0
    [m]
    SWC
    STRAT
    2160.0
    [m]
    DC
    STRAT
    2163.0
    [m]
    SWC
    STRAT
    2172.0
    [m]
    SWC
    STRAT
    2173.0
    [m]
    SWC
    STRAT
    2177.0
    [m]
    SWC
    STRAT
    2191.0
    [m]
    SWC
    STRAT
    2205.0
    [m]
    DC
    STRAT
    2209.0
    [m]
    SWC
    STRAT
    2215.0
    [m]
    DC
    STRAT
    2217.0
    [m]
    SWC
    STRAT
    2220.0
    [m]
    DC
    STRAT
    2230.0
    [m]
    DC
    STRAT
    2234.0
    [m]
    C
    STRAT
    2238.0
    [m]
    C
    STRAT
    2245.0
    [m]
    C
    STRAT
    2249.0
    [m]
    C
    STRAT
    2256.0
    [m]
    C
    STRAT
    2260.0
    [m]
    C
    STRAT
    2267.0
    [m]
    C
    STRAT
    2267.0
    [m]
    C
    RRI
    2270.0
    [m]
    C
    RRI
    2272.0
    [m]
    C
    STRAT
    2272.0
    [m]
    C
    RRI
    2273.8
    [m]
    C
    RRI
    2275.0
    [m]
    C
    RRI
    2277.0
    [m]
    C
    STRAT
    2279.0
    [m]
    C
    RRI
    2282.5
    [m]
    C
    RRI
    2284.0
    [m]
    C
    STRAT
    2298.0
    [m]
    C
    STRAT
    2308.0
    [m]
    C
    STRAT
    2308.0
    [m]
    C
    STRAT
    2314.0
    [m]
    DC
    STRAT
    2320.0
    [m]
    DC
    STRAT
    2323.0
    [m]
    SWC
    STRAT
    2324.0
    [m]
    SWC
    STRAT
    2331.0
    [m]
    SWC
    STRAT
    2346.0
    [m]
    SWC
    STRAT
    2353.0
    [m]
    SWC
    STRAT
    2365.0
    [m]
    DC
    STRAT
    2378.0
    [m]
    SWC
    STRAT
    2380.0
    [m]
    DC
    STRAT
    2395.0
    [m]
    DC
    STRAT
    2403.0
    [m]
    SWC
    STRAT
    2418.0
    [m]
    SWC
    STRAT
    2437.5
    [m]
    SWC
    STRAT
    2442.0
    [m]
    SWC
    STRAT
    2452.0
    [m]
    SWC
    STRAT
    2470.0
    [m]
    DC
    STRAT
    2485.0
    [m]
    SWC
    STRAT
    2491.0
    [m]
    SWC
    STRAT
    2498.0
    [m]
    SWC
    STRAT
    2502.0
    [m]
    SWC
    STRAT
    2510.0
    [m]
    DC
    STRAT
    2520.0
    [m]
    DC
    STRAT
    2530.0
    [m]
    DC
    STRAT
    2540.0
    [m]
    DC
    STRAT
    2542.0
    [m]
    SWC
    STRAT
    2547.0
    [m]
    SWC
    STRAT
    2550.5
    [m]
    SWC
    STRAT
    2565.0
    [m]
    DC
    STRAT
    2580.0
    [m]
    DC
    STRAT
    2590.0
    [m]
    DC
    STRAT