Seismic imaging of complex geometry: Forward modeling of sandstone intrusions

Antonio Grippa*, Andrew Hurst, Giuseppe Palladino, David Iacopini, Isabelle Lecomte, Mads Huuse

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

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    Abstract

    Sandstone intrusions form large bedding-discordant sandstones that intruded into finer grained, less permeable host strata. They form naturally sand-propped hydraulic fractures that constitute a connected network of permeable conduits through which fluids escape to the Earth's surface. Saucer-shaped sandstone intrusions are among the largest volume intrusions and are commonly resolved on seismic data. Outcrop analogues of seismically-resolved saucers-shaped intrusions reveal that many attendant intrusions, in particular dikes, are undetected in seismic data. Seismic forward modeling of a detailed outcrop description of a saucer-shaped intrusion demonstrates that intrusions steeper than 45° are undetected and that up to 40% of the entire volume of sandstone intrusions is not seismically imaged. Wedge geometry – associated with discordant contacts between different lithologies – causes constructive and destructive amplitude interference, creating imaging artefacts of sandstone thickness and geometry. Comparison of the outcrop seismic models with 3D seismic data from Volund oilfield demonstrate both the similarity of the saucer-shaped intrusions and the distribution and quantity of dikes that may be undetected (ca. 78%) using subsurface data. Lack of detection of dikes has direct implications on the valuation of upward migration of fluids and an overestimation of seal capacity. This therefore has major implications when using seismic data to evaluate waste sequestration or to execute hydrocarbon or groundwater exploration and production.

    Original languageEnglish
    Pages (from-to)51-63
    Number of pages13
    JournalEarth and Planetary Science Letters
    Volume513
    Early online date28 Feb 2019
    DOIs
    Publication statusPublished - 1 May 2019

    Keywords

    • carbon sequestration
    • sand injectites
    • sandstone intrusion
    • seismic forward modeling
    • tuning wedge
    • vertical transmissivity

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