Factpages Norwegian petroleum directorate
Factpages Norwegian petroleum directorate
NPD          Norsk
07.06.2023 - 01:35
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25/8-8 A

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  • General information

    General information
    Attribute Value
    Wellbore name
    Official name of wellbore based on NPD guidelines for designation of wells and wellbores.
    25/8-8 A
    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).
    APPRAISAL
    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 NPD.
    INJECTING: It was injected to the wellbore at the time of the operators last monthly report to the NPD.
    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
    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 NPD guidelines for designation of wells and wellbores.
    25/8-8
    Seismic location
    Position of spud location on seismic survey lines. SP: shotpoint.
    ES 9403- INLINE 2672 & CDP 2131
    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 NPD.
    830-L
    Drilling facility
    NPD's name of the facility which the wellbore was drilled from.
    Drilling days
    Number of days from wellbore entry to wellbore completion.
    13
    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,
    29.09.1995
    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.
    11.10.1995
    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.
    11.10.1997
    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.
    APPRAISAL
    Reentry
    Status whether the wellbore has been re-entered (YES) or not (NO). Re-entered wellbores are not included in the count when wellbores are presented in statistical overviews.
    NO
    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.
    NO
    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 NPD 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 NPD 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).
    2601.0
    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).
    2183.1
    Maximum inclination [°]
    Maximum deviation, in degrees, from a vertical well path.Shown only for released wells.
    51.7
    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.
    PALEOCENE
    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.
    TY 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
    NPD's unique id for the wellbore.
    2690
  • 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 NPD

    Cuttings at the NPD
    Cuttings available for sampling?
    YES
    Cuttings at the NPD
    Cutting sample, top depth [m]
    Cutting samples, bottom depth [m]
    1060.00
    2601.30
  • Cores at the NPD

    Cores at the NPD
    Core sample number
    Core sample - top depth
    Core sample - bottom depth
    Core sample depth - uom
    1
    2414.0
    2450.0
    [m ]
    2
    2450.0
    2464.3
    [m ]
    3
    2464.3
    2496.0
    [m ]
    4
    2496.0
    2523.7
    [m ]
    Cores at the NPD
    Total core sample length [m]
    109.6
    Cores at the NPD
    Cores available for sampling?
    YES
  • Core photos

    Core photos
    Core photo at depth: 2414-2419m
    Core photo at depth: 2419-2424m
    Core photo at depth: 2424-2429m
    Core photo at depth: 2429-2434m
    Core photo at depth: 2434-2439m
    2414-2419m
    2419-2424m
    2424-2429m
    2429-2434m
    2434-2439m
    Core photo at depth: 2439-2444m
    Core photo at depth: 2444-2449m
    Core photo at depth: 2449-2450m
    Core photo at depth: 2450-2455m
    Core photo at depth: 2455-2460m
    2439-2444m
    2444-2449m
    2449-2450m
    2450-2455m
    2455-2460m
    Core photo at depth: 2460-2464m
    Core photo at depth: 2464-2469m
    Core photo at depth: 2469-2474m
    Core photo at depth: 2474-2479m
    Core photo at depth: 2479-2484m
    2460-2464m
    2464-2469m
    2469-2474m
    2474-2479m
    2479-2484m
    Core photo at depth: 2484-2489m
    Core photo at depth: 2489-2494m
    Core photo at depth: 2494-2495m
    Core photo at depth: 2495-2500m
    Core photo at depth: 2500-2505m
    2484-2489m
    2489-2494m
    2494-2495m
    2495-2500m
    2500-2505m
    Core photo at depth: 2505-2510m
    Core photo at depth: 2510-2515m
    Core photo at depth: 2515-2520m
    Core photo at depth: 2520-2524m
    Core photo at depth:  
    2505-2510m
    2510-2515m
    2515-2520m
    2520-2524m
  • Palynological slides at the NPD

    Palynological slides at the NPD
    Sample depth
    Depth unit
    Sample type
    Laboratory
    2240.0
    [m]
    SWC
    STRAT
    2271.0
    [m]
    SWC
    STRAT
    2280.0
    [m]
    SWC
    STRAT
    2282.0
    [m]
    SWC
    STRAT
    2284.0
    [m]
    SWC
    STRAT
    2290.0
    [m]
    DC
    STRAT
    2296.0
    [m]
    SWC
    STRAT
    2300.0
    [m]
    DC
    STRAT
    2320.0
    [m]
    DC
    STRAT
    2330.0
    [m]
    DC
    STRAT
    2335.0
    [m]
    SWC
    STRAT
    2340.0
    [m]
    DC
    STRAT
    2350.0
    [m]
    SWC
    STRAT
    2354.0
    [m]
    SWC
    STRAT
    2356.0
    [m]
    SWC
    STRAT
    2370.0
    [m]
    DC
    STRAT
    2375.0
    [m]
    SWC
    STRAT
    2395.0
    [m]
    SWC
    STRAT
    2398.0
    [m]
    SWC
    STRAT
    2414.0
    [m]
    C
    STRAT
    2425.0
    [m]
    C
    STRAT
    2426.0
    [m]
    C
    STRAT
    2430.0
    [m]
    C
    STRAT
    2434.0
    [m]
    C
    STRAT
    2436.0
    [m]
    C
    STRAT
    2438.0
    [m]
    C
    STRAT
    2446.0
    [m]
    C
    STRAT
    2449.0
    [m]
    C
    STRAT
    2467.0
    [m]
    C
    STRAT
    2481.0
    [m]
    C
    STRAT
    2495.0
    [m]
    C
    STRAT
    2498.0
    [m]
    C
    STRAT
    2503.0
    [m]
    C
    STRAT
    2511.0
    [m]
    C
    STRAT
    2521.0
    [m]
    C
    STRAT
    2521.0
    [m]
    C
    STRAT
    2530.0
    [m]
    DC
    STRAT
    2542.8
    [m]
    SWC
    STRAT
    2552.9
    [m]
    SWC
    STRAT
    2560.0
    [m]
    DC
    STRAT
    2570.0
    [m]
    DC
    STRAT
    2582.0
    [m]
    SWC
    STRAT
    2590.0
    [m]
    DC
    STRAT
    2601.3
    [m]
    DC
    STRAT
  • Lithostratigraphy

  • 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
    91.01
  • Logs

    Logs
    Log type
    Log top depth [m]
    Log bottom depth [m]
    AIT AS GR CAL
    1046
    2592
    CST GR
    2240
    2585
    IPL EPT NGS
    1046
    2593
    MDT GR
    2426
    2429
    MDT GR
    2430
    2516
    MDT GR
    2430
    2560
    MDT GR
    2560
    2576
    MWD - GR RES DIR
    1124
    2592
    VSP
    1390
    2580
  • 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
    214.0
    36
    214.0
    0.00
    LOT
    SURF.COND.
    13 3/8
    1046.0
    17 1/2
    1046.0
    0.00
    LOT
    OPEN HOLE
    2601.0
    8 1/2
    2601.0
    0.00
    LOT
  • Drilling mud

    Drilling mud
    Depth MD [m]
    Mud weight [g/cm3]
    Visc. [mPa.s]
    Yield point [Pa]
    Mud type
    Date measured
    841
    1.49
    61.0
    OIL BASED
    996
    1.43
    38.0
    OIL BASED
    1070
    1.00
    37.0
    OIL BASED
    1149
    1.43
    44.0
    OIL BASED
    1334
    1.54
    51.0
    OIL BASED
    2115
    1.50
    43.0
    OIL BASED
    2154
    1.43
    42.0
    OIL BASED
    2230
    1.50
    54.0
    OIL BASED
    2242
    1.54
    37.0
    OIL BASED
    2382
    1.50
    45.0
    OIL BASED
    2414
    1.50
    49.0
    OIL BASED
    2443
    1.50
    44.0
    OIL BASED
    2450
    1.54
    38.0
    OIL BASED
    2495
    1.53
    37.0
    OIL BASED
    2510
    1.50
    53.0
    OIL BASED
    2522
    1.53
    36.0
    OIL BASED
    2601
    1.53
    36.0
    OIL BASED
  • Thin sections at the NPD

    Thin sections at the NPD
    Depth
    Unit
    2430.75
    [m ]
    2436.10
    [m ]
    2447.25
    [m ]
    2449.75
    [m ]
    2456.85
    [m ]
    2461.25
    [m ]
    2461.45
    [m ]
    2476.00
    [m ]
    2454.75
    [m ]
    2485.00
    [m ]
    2428.30
    [m ]
    2433.20
    [m ]
    2448.20
    [m ]
    2457.85
    [m ]
    2458.20
    [m ]
    2463.25
    [m ]
    2465.80
    [m ]
    2485.80
    [m ]
    2504.25
    [m ]
    2506.25
    [m ]
    2517.50
    [m ]
  • Pressure plots

    Pressure plots
    The pore pressure data is sourced from well logs if no other source is specified. In some wells where pore pressure logs do not exist, information from Drill stem tests and kicks have been used. The data has been reported to the NPD, and further processed and quality controlled by IHS Markit.
    Pressure plots
    Document name
    Document format
    Document size [MB]
    pdf
    0.21