Central North Sea overpressures: insights into fluid flow from one- and two-dimensional basin modelling

D Darby, R S Haszeldine, Gary Douglas Couples

    Research output: Chapter in Book/Report/Conference proceedingChapter

    13 Citations (Scopus)


    Jurassic and Triassic reservoirs in the Central North Sea are highly overpressured
    (>40 MPa above hydrostatic pressure). Simulation of the interplay between rapid Tertiary subsidence, seal permeability and fluid flow allows insight into the geological controls on the distribution and magnitude of the overpressure. One-dimensional models demonstrate that, unlike other basins, the overpressure developed in the Graben is not determined by the thickness and permeability of the shale pressure seal. A two-dimensional model simulating lateral flow beneath
    the pressure seal provides an accurate simulation of the overpressure distribution. Disequilibrium compaction of shale-dominated off-structure regions forms the principal overpressuring mechanism. Lateral flow in the permeable Fuhnar sandstones leads to high overpressure and focused vertical escape on an axial high, where the seal is thinner above a subcropping Fulmar Fm. A layered hydrogeological regime is suggested, with shallow Tertiary pressure cells separated from deep Cretaceous-Triassic pressure cells by normally pressured, permeable Palaeocene sandstones. The pre-Cretaceous rift-associated configuration of the Graben, in combination with 3 km of Tertiary subsidence, controls the distribution of overpressure.
    Original languageEnglish
    Title of host publicationBasin modelling
    Subtitle of host publicationpractice and progress
    EditorsS J Duppenbecker, J E Iliffe
    Place of PublicationLondon
    PublisherGeological Society of London
    Number of pages13
    ISBN (Print)1862390088
    Publication statusPublished - Dec 1998

    Publication series

    NameGeological Society special publication
    PublisherGeological Society of London
    ISSN (Print)0305-8719
    ISSN (Electronic)2041-4927


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