Abstract

A three-dimensional (3-D) 100 MHz ground-penetrating radar (GPR) data volume is the basis of in-situ characterization of a fluvial reservoir analog in the Ferron Sandstone of east-central Utah. We use the GPR reflection times to image the bounding surfaces via 3-D velocity estimation and depth migration, and we use the 3-D amplitude distribution to generate a geostatistical model of the dimensions, orientations, and geometries of the internal structures from the surface down to ∼12 m depth. Each sedimentological element is assigned a realistic fluid permeability distribution by kriging with the 3-D correlation structures derived from the GPR data and which are constrained by the permeabilities measured in cores and in plugs extracted from the adjacent cliff face.

The 3-D GPR image shows that GPR facies changes can be interpreted to locate sedimentological bounding surfaces, even when the surfaces do not correspond to strong GPR reflections. The site contains two main sedimentary regimes. The upper ∼5 m contain trough cross-bedded sandstone with average permeability of ∼40 md and maximum correlation lengths ∼(5.5–12.5) × (3.5–8.0) × (0.2–1.5) m. The lower ∼7 m contain scour and fill fluvial deposits with average permeability varying from ∼30 md to ∼15 md as clay content increases, and maximum correlation lengths ∼(4.0–12.5) × (3.0–10.0) × (0.5–1.0) m. These representations are suitable for input to fluid flow modeling.

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