Constructing a Three-Dimensional Rock-Property Model of Fluvial Sandstones in The Peoria Field, Colorado
Mark A. Chapin, David F. Mayer, 1991. "Constructing a Three-Dimensional Rock-Property Model of Fluvial Sandstones in The Peoria Field, Colorado", The Three-Dimensional Facies Architecture of Terrigenous Clastic Sediments and its Implications for Hydrocarbon Discovery and Recovery, Andrew D. Miall, Noel Tyler
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Fluid-flow units and fluid-flow barriers are distinguished through mapping distributions of facies and bounding surfaces of coalesced channel belts within the Lower Cretaceous J Sandstone in the Peoria field, Colorado. Measured rock properties (porosity, permeability, relative permeability, and capillary pressure) were calibrated to facies, which were distinguished by common associations of grain sizes, clay content, and sedimentary structures. The three-dimensional distribution of rock properties in the J sandstone reservoir was obtained through facies mapping. Within a meander belt, trough cross-stratified and clean, ripple-laminated point-bar sandstones act as flow units, and clay-rich abandonment fills act as flow barriers. Hydraulic communication between vertically stacked channel belts depends on the thickness and continuity of muddy sandstones having abundant clay inclusions that commonly overlie basal scour surfaces. The effect of smaller scale sedimentary bounding surfaces on fluid flow was not measurable at the scale of the well spacing and engineering data available. Compartmentalization of the reservoir is indicated by two elevations of oil-water contacts along the downdip, west flank of the field. This is explained by a concentration of abandonment-fill facies and a lack of hydraulic communication between coalesced channel belts in the center of the field. Pre- and post-injection production patterns are explained by the geologic model.