Three-dimensional ground penetrating radar (GPR) imaging, detailed sedimentology and stratigraphy, petrographic analysis, and laboratory measurements of porosity and permeability are combined to characterize part of a fluvial channel deposit in the Cretaceous Ferron Sandstone. The near surface study covers an area of 40 m x 16.5 m to a depth of 15 m. Detailed cliff-face measured sections indicate the deposit comprises five distinct sandstone units. High-resolution 3-D GPR surveys at 50, 100 and 200 MHz imaged the subsurface adjacent to the cliff-face. Four 15-m deep boreholes behind the cliff-face yielded nearly complete ª6 cm diameter (2.5 in) core (>95% recovery). These cores, together with the cliff-face data, provide control for interpretating the GPR data. Permeability measurements of ª2.5 cm (1 in) plugs extracted from the cliff-face and on split core range from 0.6 to 326 md. The highest permeabilities occur in a trough cross-bedded sandstone; the lowest permeabilities occur in thin siltstone and mudstone layers separating sandstone units. Porosity measurements range from 0.11 to 0.24. Petrographic analysis of plugs suggests that up to half the porosity in some sandstone units may be within interstitial clays, possibly decreasing the “effective” porosity. The 3-D framework inferred from the GPR data is populated with permeability data using geostatistical methods to construct petrophysical models for subsequent flow simulation. Simulation results suggest that very simple models are sufficient to describe the permeability structure of these types of deposits.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah