Coupling Diagenesis and Petrophysics in red Bed Siliclastics to Infer Fluid Flow Anisotropies - Analog Studies from SW Germany

  • Name:

    EAGE

  • Venue:

    Kopenhagen

  • Date:

    11.-14.Juni

  • Author:

    Schmidt C, Busch B, Hilgers C

  • Speaker:

    Schmidt C

  • Source:

    earthdoc.eage.org

  • Heterogeneity in siliciclastics is a factor, which is regularly underestimated when dealing with a conventional play. The assumption that the reservoir unit can be represented by a sand box has been proven wrong by production rates, which points out that understanding sedimentation and diagenesis is necessary for reservoir characterization. This study links petrophysics and diagenesis on different scales within red beds: Beginning by evaluating the influence of lithofacies types on fluid flow, we measure the effects in 3D. Samples were taken in two Lower Triassic fluvial deposits in the S-Germany, as well as in eolian lithologies: a Lower Permian outcrop in N-Germany and a coeval site in N-England, both analogs for subsurface reservoirs. Small-scale sedimentary features are assessed regarding their character as across-flow barrier or catalyzer in eolianites. Second order bounding surfaces show porosities decreasing from 13 to 7 % and carbonate cements while third order planes enhance permeability by a maximum of 80 mD. The latter results from the surface being reactivated and/or secondary dissolution taking place. While the fluvial deposits feature different lithotypes within one reservoir rock, the eolian samples supply homogenous samples that illustrate the influence of sedimentary structures and can be taken as red bed proxies.