--> Reconstructing 3-D Fluvial Channel Belt Stratigraphy Using Time-Lapse Satellite Images

AAPG ACE 2018

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Reconstructing 3-D Fluvial Channel Belt Stratigraphy Using Time-Lapse Satellite Images

Abstract

High-resolution three-dimensional models of fluvial channel belt stratigraphy are constructed using multiple time-lapse satellite images to map the evolution of topographic surfaces. These surfaces bound bed-scale deposits and are used to spatially reference predictions of grain size variability. The volume created by combining all of the surfaces describes the three-dimensional architecture of channel belts in a more realistic manner than comparative models that simulate the physics of fluid flow and sediment transport. Moreover, the modeling approaches described here are fast, can be applied to any fluvial style, and create results that can be directly compared to the modern analogues from which they’re derived.

Access to satellite imagery that frequently records earth surfaces processes has opened a new frontier in the study of large-scale river dynamics. By tracking river position over time, we can map the aerial coverage of channel belt deposits. Using measurements of channel depth and a conceptual understanding of how depth varies physiographically within active channels, we can recreate three-dimensional surface topography at every image time step. We introduce a novel geometric method for automatically extracting the centerline of multi-thread rivers, and show how this can be used to enable a rules-based modeling workflow to distribute grain size as a function of position within the active channel.

Channel belt models created following these techniques offer insight into the spectrum of physical attributes within fluvial deposits. These insights can assist the characterization of analogous systems using subsurface data. For example, petrophysical heterogeneity is shown to vary significantly between river styles, and a reliable understanding of the statistics of complex remnant features is difficult to obtain from other forms of analog which don’t record three-dimensional dynamic channel belt evolution. The models presented here can be analyzed to help identify what characteristics should be expected in well and seismic data, inform the physical ranges of inputs that are required for geostatistical reservoir modeling, and form a robust basis for simulation studies that seek to quantify the influence of depositional heterogeneity on fluid flow behavior.