Factpages Norwegian petroleum directorate
Factpages Norwegian petroleum directorate
NPD          Norsk
09.06.2023 - 01:35
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31/2-1

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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.
    31/2-1
    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 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.
    SUSPENDED
    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.
    31/2-1
    Seismic location
    Position of spud location on seismic survey lines. SP: shotpoint.
    77 - 6046 SP 461
    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.
    A/S Norske Shell
    Drill permit
    The drilling permit number together with the version of the drilling permit as stated in the drilling permit granted by the NPD.
    219-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.
    116
    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,
    17.07.1979
    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.
    09.11.1979
    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.
    09.11.1981
    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.
    15.02.2006
    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
    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.
    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 NPD bulletins.
    LATE JURASSIC
    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.
    SOGNEFJORD FM
    Kelly bushing elevation [m]
    Elevation of the rotary kelly bushing (RKB) above mean sea level.
    24.0
    Water depth [m]
    Depth in metres betweem mean sea level and sea floor.
    324.0
    Total depth (MD) [m RKB]
    Total measured length of wellbore from kelly bushing to total depth (driller's depth).
    2433.0
    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).
    2433.0
    Bottom hole temperature [°C]
    Estimated temperature at final total depth of the wellbore. Shown only for released wells. See discription.
    65
    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 TRIASSIC
    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.
    HEGRE GP
    Geodetic datum
    Reference system for coordinates. Example of legal values: ED50.
    ED50
    NS degrees
    Geographic coordinate of the wellhead, north-south degrees.
    60° 46' 19.16'' N
    EW degrees
    Geographic coordinate of the wellhead, east-west degrees.
    3° 33' 15.87'' E
    NS UTM [m]
    Universal Transverse Mercator coordinate of the wellhead, north-south.
    6737677.61
    EW UTM [m]
    Universal Transverse Mercator coordinate of the wellhead, east-west.
    530201.60
    UTM zone
    Universal Transverse Mercator zone. Examples of legal values: 31, 32, 33, 34.
    31
    NPDID wellbore
    NPD's unique id for the wellbore.
    398
  • Wellbore history

    General
    Well 31/2-1 is the Troll West gas and oil Discovery well. The purpose of the well was to establish the basic stratigraphy in the area, and to evaluate the prospectivity of the Jurassic sequence. The structure is formed by a tilted Jurassic fault block on the Sogn Spur High between the North Viking Graben and the Horda Basin. A migration path from the Viking Graben kitchen area is provided by monoclinal fault blocks. The most dominant characteristic of the structure was the presence of a "flatspot", which was believed to be associated with a present hydrocarbon/water contact. Sealing of the potential Jurassic reservoir is provided by Cretaceous and Paleocene Claystones, overlying the reservoir sandstones.
    The well is Type Well for the Johansen, Krossfjord, Fensfjord, and the Sognefjord Formations, and Reference Well for the Amundsen, Cook, and Drake Formations.
    Operations and results
    Wildcat well 31/2-1 was spudded with the semi-submersible installation Borgny Dolphin on 17 July 1979 and drilled to TD at 2433 m in the Late Triassic Hegre Group. Severe problems with setting the 30" casing led to abandoning of the first hole and re-spudding on 24 July, 50 m to the south of the original spud position. The well was drilled with gel polymer down to 793 m, and with gypsum/lignosulphonate mud from 793 m to TD.
    The well 31/2-1 proved the existence of a Late - Middle Jurassic gas bearing reservoir sequence in the Flathead A structure (block 31/2). A gross commercial gas column of 134.5 metres with top at 1439.5 m was encountered in good-moderate quality coastal - shallow marine sands. Good oil shows with oil bleeding from cores were encountered from 1567 m to 1597 m, below the gas. It is possible that both a gas-oil contact and an oil-water contact occur in this zone, however, data available suggested tight formation. From the pressure data the plausible interpretation is that a gas-water contact effectively exists at the intersection of the extrapolated gas and water pressure gradients at 1574 m (1550 m SS), which would imply that the oil observed in cores is actually residual. Indications of oil occurred down to 1622 m. The well results showed that the marked seismic flatspot seen on seismic lines across the structure at 1685 msec was closely related to the base of the gas column. For a detailed evaluation of the reservoir it was decided to take diamond bit cores over the whole hydrocarbon bearing Jurassic interval. A total of 18 cores were cut in the interval from 1450 to 1668 m, with a recovery length of 182 m (86%). The cored interval extends from just below the top reservoir to below the hydrocarbon/water contact. Extensive RFT pressure measurements showed the accumulation to be under hydrostatic conditions. Good RFT gas samples were recovered from 1442 m, 1468 m, 1482 m, 1515 m, 1547.5 m, 1573 m, and 1574 m. They showed a consistent dry gas composition with 93% methane, 0.5% CO2, and 1.5% N2. Only trace C4+ and no H2S was recorded. A number of RFT water samples were found to be heavily contaminated by the mud and not representative for the Formation.
    The well was suspended on 9 November for re-entry and possible testing at a later stage.
    Testing
    After RFT testing preparations were made for drill stem testing of the interval where oil had been observed bleeding from cores (1565 to 1622 m). Due to severe weather and technical problems the test was aborted.
  • 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]
    480.00
    2433.00
  • Cores at the NPD

    Cores at the NPD
    Core sample number
    Core sample - top depth
    Core sample - bottom depth
    Core sample depth - uom
    1
    1450.0
    1453.5
    [m ]
    2
    1454.0
    1455.5
    [m ]
    3
    1456.6
    1465.6
    [m ]
    4
    1465.6
    1474.6
    [m ]
    5
    1474.6
    1485.6
    [m ]
    6
    1488.0
    1493.3
    [m ]
    7
    1514.0
    1521.8
    [m ]
    8
    1523.6
    1532.7
    [m ]
    9
    1533.0
    1541.8
    [m ]
    10
    1542.0
    1559.0
    [m ]
    11
    1560.0
    1577.4
    [m ]
    12
    1577.4
    1595.5
    [m ]
    13
    1595.5
    1613.5
    [m ]
    14
    1613.5
    1616.6
    [m ]
    15
    1617.5
    1634.1
    [m ]
    16
    1634.1
    1638.4
    [m ]
    17
    1638.4
    1652.1
    [m ]
    18
    1652.3
    1662.7
    [m ]
    Cores at the NPD
    Total core sample length [m]
    186.2
    Cores at the NPD
    Cores available for sampling?
    YES
  • Core photos

    Core photos
    Core photo at depth: 1450-1452m
    Core photo at depth: 1452-1453m
    Core photo at depth: 1454-1455m
    Core photo at depth: 1456-1459m
    Core photo at depth: 1459-1462m
    1450-1452m
    1452-1453m
    1454-1455m
    1456-1459m
    1459-1462m
    Core photo at depth: 1462-1464m
    Core photo at depth: 1464-1465m
    Core photo at depth: 1465-1468m
    Core photo at depth: 1468-1471m
    Core photo at depth: 1471-1473m
    1462-1464m
    1464-1465m
    1465-1468m
    1468-1471m
    1471-1473m
    Core photo at depth: 1373-1474m
    Core photo at depth: 1474-1477m
    Core photo at depth: 1477-1480m
    Core photo at depth: 1480-1482m
    Core photo at depth: 1482-1485m
    1373-1474m
    1474-1477m
    1477-1480m
    1480-1482m
    1482-1485m
    Core photo at depth: 1485-1486m
    Core photo at depth: 1488-1490m
    Core photo at depth: 1490-1493m
    Core photo at depth: 1514-1516m
    Core photo at depth: 1516-1519m
    1485-1486m
    1488-1490m
    1490-1493m
    1514-1516m
    1516-1519m
    Core photo at depth: 1519-1521m
    Core photo at depth: 1523-1526m
    Core photo at depth: 1526-1529m
    Core photo at depth: 1529-1531m
    Core photo at depth: 1531-1531m
    1519-1521m
    1523-1526m
    1526-1529m
    1529-1531m
    1531-1531m
    Core photo at depth: 1533-1535m
    Core photo at depth: 1535-1538m
    Core photo at depth: 1538-1541m
    Core photo at depth: 1541-1542m
    Core photo at depth: 1542-1544m
    1533-1535m
    1535-1538m
    1538-1541m
    1541-1542m
    1542-1544m
    Core photo at depth: 1544-1547m
    Core photo at depth: 1547-1550m
    Core photo at depth: 1550-1552m
    Core photo at depth: 1552-1555m
    Core photo at depth: 1555-1558m
    1544-1547m
    1547-1550m
    1550-1552m
    1552-1555m
    1555-1558m
    Core photo at depth: 1558-1559m
    Core photo at depth: 1560-1562m
    Core photo at depth: 1562-1565m
    Core photo at depth: 1565-1568m
    Core photo at depth: 1568-1570m
    1558-1559m
    1560-1562m
    1562-1565m
    1565-1568m
    1568-1570m
    Core photo at depth: 1570-1573m
    Core photo at depth: 1573-1576m
    Core photo at depth: 1576-1577m
    Core photo at depth: 1577-1580m
    Core photo at depth: 1580-1582m
    1570-1573m
    1573-1576m
    1576-1577m
    1577-1580m
    1580-1582m
    Core photo at depth: 1582-1585m
    Core photo at depth: 1585-1588m
    Core photo at depth: 1588-1590m
    Core photo at depth: 1590-1593m
    Core photo at depth: 1593-1595m
    1582-1585m
    1585-1588m
    1588-1590m
    1590-1593m
    1593-1595m
    Core photo at depth: 1595-1598m
    Core photo at depth: 1598-1600m
    Core photo at depth: 1600-1603m
    Core photo at depth: 1603-1606m
    Core photo at depth: 1606-1609m
    1595-1598m
    1598-1600m
    1600-1603m
    1603-1606m
    1606-1609m
    Core photo at depth: 1609-1611m
    Core photo at depth: 1611-1613m
    Core photo at depth: 1613-1616m
    Core photo at depth: 1616-1617m
    Core photo at depth: 1620-1622m
    1609-1611m
    1611-1613m
    1613-1616m
    1616-1617m
    1620-1622m
    Core photo at depth: 1622-1625m
    Core photo at depth: 1625-1628m
    Core photo at depth: 1628-1631m
    Core photo at depth: 1631-1633m
    Core photo at depth: 1633-1634m
    1622-1625m
    1625-1628m
    1628-1631m
    1631-1633m
    1633-1634m
    Core photo at depth: 1634-1636m
    Core photo at depth: 1636-1638m
    Core photo at depth: 1638-1641m
    Core photo at depth: 1641-1643m
    Core photo at depth: 1643-1646m
    1634-1636m
    1636-1638m
    1638-1641m
    1641-1643m
    1643-1646m
    Core photo at depth: 1646-1649m
    Core photo at depth: 1649-1651m
    Core photo at depth: 1651-1652m
    Core photo at depth: 1652-1655m
    Core photo at depth: 1655-1657m
    1646-1649m
    1649-1651m
    1651-1652m
    1652-1655m
    1655-1657m
    Core photo at depth: 1657-1660m
    Core photo at depth: 1660-1663m
    Core photo at depth:  
    Core photo at depth:  
    Core photo at depth:  
    1657-1660m
    1660-1663m
  • Lithostratigraphy

  • Composite logs

    Composite logs
    Document name
    Document format
    Document size [MB]
    pdf
    0.35
  • Geochemical information

    Geochemical information
    Document name
    Document format
    Document size [MB]
    pdf
    0.74
    pdf
    3.93
    pdf
    1.13
    pdf
    0.63
  • 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
    16.05
  • Logs

    Logs
    Log type
    Log top depth [m]
    Log bottom depth [m]
    BGT GR
    426
    798
    BGT GR
    793
    1324
    CBL VDL
    1310
    2074
    CBL VDL GR
    344
    2035
    DLL MSFL SP GR
    1310
    1703
    FDC BHC GR SP
    1310
    1703
    FDC CNL CAL GR
    426
    575
    FDC CNL CAL GR
    793
    1323
    FDC CNL CAL GR
    1310
    1381
    FDC CNL CAL GR
    1550
    2070
    FDC CNL CAL GR
    2063
    2432
    HDT
    1310
    2070
    HDT
    2063
    2432
    ISF BHC GR SP
    426
    578
    ISF BHC GR SP
    793
    1322
    ISF BHC GR SP
    1310
    1379
    ISF BHC GR SP
    1310
    1703
    ISF BHC GR SP
    1550
    2070
    ISF BHC GR SP
    2063
    2432
    ISF GR SP
    793
    1220
    LSS GR
    426
    479
    LSS GR
    793
    1321
    LSS GR
    1310
    2070
    MSFL GR CAL
    1310
    1379
    RFT
    1308
    1336
    RFT
    1308
    1701
    RFT
    1308
    2433
    VELOCITY
    0
    0
  • 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
    423.0
    36
    470.0
    0.00
    LOT
    SURF.COND.
    20
    793.0
    26
    805.0
    1.52
    LOT
    INTERM.
    13 5/8
    1308.0
    17 1/2
    1322.0
    1.67
    LOT
    INTERM.
    9 5/8
    2061.0
    12 1/4
    2074.0
    1.60
    LOT
    OPEN HOLE
    2433.0
    8 1/2
    2433.0
    0.00
    LOT
  • Drilling mud

    Drilling mud
    Depth MD [m]
    Mud weight [g/cm3]
    Visc. [mPa.s]
    Yield point [Pa]
    Mud type
    Date measured
    793
    1.09
    waterbased
    1308
    1.37
    waterbased
    2080
    1.33
    waterbased
    2433
    1.33
    waterbased