The integration of well information with seismic amplitude is a powerful tool for locating lateral facies boundaries to construct improved facies architectural models. This paper addresses an approach that relates the petrophysical parameters calculated for selected middle Frio reservoirs to the RMS seismic amplitudes calculated in a 10ms window. The suite of petrophysical parameters related to the RMS seismic amplitude includes net pay thickness, hydrocarbon pore volume, gas saturation, net sand thickness, and effective porosity. The results indicate that the most reliable rock property that can be extracted from the RMS seismic amplitude is the net sand thickness (R2 =0.82). Cross plotting RMS amplitude vs. net sand thickness, net pay thickness and hydrocarbon pore volume illustrates that higher values of net pay thickness and hydrocarbon pore volume are related to higher values of RMS seismic amplitudes. This implies that the RMS seismic amplitude can be used to delineate the lateral extent of the channel-fill deposits of the middle Frio Formation at Stratton and Agua Dulce fields in south Texas. The number of sandstone bodies was also related to RMS seismic amplitude and can be used to predict the location of the middle Frio horizons composed of several vertically stacked channel-fill sandstone bodies. The results of this study can be applied to the other middle Frio Formation reservoirs in the Stratton-Agua Dulce fields and in the Texas Gulf Coast.