The effect of intra-reservoir shales on effective stress sensitivity

Y. HajNasser, C. MacBeth

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    In most clastic reservoirs experiencing pressure depletion, the sands in the reservoir naturally compact. As a consequence, the much lower permeability reservoir shales may experience extension. This extension is counteracted to some degree by pressure equilibration of the shale. The effective seismic response of the reservoir interval may thus be a mix of both hardening and softening reservoir components, depending on the balance of these phenomena. This effect is predicted to alter the overall stress sensitivity of the seismic properties from that anticipated for a homogeneous, fully connected reservoir interval. However, the final resultant response depends on the time period over which this effect is observed. Numerical computation using simplified geological models indicates shales of 1m to 10m thickness should be taken into account when quantitatively assessing the 4D seismic signature from frequently shot time-lapse surveys with a periodicity of 3 to 12 months, whilst 5 to 10m thick shales could impact conventional 4D seismic surveys shot over 5 to 10 years. These conclusions are strongly affected by the mechanical and transport properties of the intra-reservoir shales, their thickness and distribution, and are hence also a function of the depositional environment.© 2010, Society of Petroleum Engineers.

    Original languageEnglish
    Title of host publicationSociety of Petroleum Engineers - 72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010 - Incorporating SPE EUROPEC 2010
    Pages2159-2163
    Number of pages5
    Volume3
    Publication statusPublished - 2010
    Event72nd EAGE Conference & Exhibition - Barcelona, Spain
    Duration: 14 Jun 201017 Jun 2010

    Conference

    Conference72nd EAGE Conference & Exhibition
    Abbreviated titleSPE EUROPEC 2010
    CountrySpain
    CityBarcelona
    Period14/06/1017/06/10

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  • Cite this

    HajNasser, Y., & MacBeth, C. (2010). The effect of intra-reservoir shales on effective stress sensitivity. In Society of Petroleum Engineers - 72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010 - Incorporating SPE EUROPEC 2010 (Vol. 3, pp. 2159-2163)