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    Olje og gass

    The story behind

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    Oil was found in the second well on the NCS. However, it took almost 30 years before the operator delivered a PDO.
    Dag Bergslien was raised in Stavanger and recalls both when Ocean Traveler came to Stavanger for the first time and the very first helicopter flights from Sola in 1966. Later he became interested in geology, and after graduation he ended up in Esso. Many challenging years was needed to understand the reservoir in the Balder field. The core is from the reservoir in 25/11-1. Photo: Halfdan Carstens

    Dag Bergslien was raised in Stavanger and recalls both when Ocean Traveler came to Stavanger for the first time and the very first helicopter flights from Sola in 1966. Later he became interested in geology, and after graduation he ended up in Esso. Many challenging years was needed to understand the reservoir in the Balder field. The core is from the reservoir in 25/11-1. Photo: Halfdan Carstens

    The Balder field came on stream in 1996. It is less well known that he discovery well, 25/11-1 drilled in 1967, was the second wildcat on the NCS.
    Dag Bergslien, who has dedicated his entire carrier to Esso, will tell the story behind the discovery in the forthcoming seminar February 28 in the Hydrocarbon Habitat series that we have named “A 100-year perspective”.

    «Well 25/111 was the first clear indication that there could be commercial deposits of oil in the Norwegian North Sea sector.»
    Dag Bergslien

    The title of this talk is: “The story behind the discovery: The very first oil in the North Sea, and the troublesome appraisal towards a PDO”.
    Hydrocarbon Habitats February 28, Stavanger.
    The story is also told in GEO 04/2017: «50 år siden første oljefunn».
    Well 25/11-1 was drilled in PL 001. Today we know that this acreage includes part of Johan Sverdrup, Edvard Grieg, Ivar Aasen, Grane as well as Balder.

    A 100-year perspective

    Injeksjonssander
    Dag Bergslien mener Balder-feltet er det første feltet i verden der det ble forstått og dokumentert at sandinjeksjoner (injektitter) utgjør en vesentlig del av reservoaret, og at de er ansvarlige for kommunikasjon og felles kontakt i klusteret av mange mindre akkumulasjoner som feltet består av.  Det var Bergslien som først benyttet begrepet «sandinjeksjon». Senere fikk han bekreftet at dette var en riktig tolkning gjennom testproduksjonsbrønnen 25/11-14.   Ideen om «liquifaction» og tilhørende sandinjeksjoner ble til da tradisjonelle avsetningsmodeller ikke kunne forklare observasjoner mht. fordelingen av sandstein i reservoaret.  I litteraturen var injeksjonssander omtalt som «dyke» og «sill». Bergslien påpeker av vi i ettertid kan si at sandsteinene som ble kjernetatt i 25/11-1 var injeksjonssander. Han viser til at det i kjernebeskrivelsen står følgende: «Dips near the top of the core averaged 8° whereas at the base the dips increased to 20-35°.  The shale, siltstone, and sandstone beds generally exhibited sharp contacts and occasionally size gradation within a bed». Alt sammen karakteristisk for denne type «avsetninger».

     

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