Most existing reservoir models are based on 2-D outcrop studies; 3-D
aspects are inferred from correlation between wells, and so are
inadequately constrained for reservoir simulations. To overcome these
deficiencies, we have initiated a multidimensional characterization of
reservoir analogs in the Cretaceous Ferron Sandstone in Utah. Detailed
sedimentary facies maps of cliff faces define the geometry and
distribution of reservoir flow units, barriers and baffles at the outcrop.
High resolution 2-D and 3-D ground-penetrating radar (GPR) images extend
these reservoir characteristics into 3-D, to allow development of
realistic 3-D reservoir models. Models use geometric information from
mapping and the GPR data, combined with petrophysical data from surface
and cliff-facs outcrops, and lab analyses of outcrop and core samples.

The site of the fiels work is Corbula Gulch, on the western flank of the
San Refael Swell, in east-central Utah. The outcrop consists of an 8--17 m
thick sandstone body which contains various sedimentary structures, such
as cross bedding, inclined stratification, and erosional surfaces, which
range in scale from less than a meter to hundreds of meters. 3-D prestack
migration of the GPR data produces data volumes within which the
structures are visible. Correlation between fluid permeability, clay
content, and instantaneous frequency and instantaneous amplitude of the
GPR data provides estimates of the 3-D distribution of fluid permeability
and clay content.