Forward Seismic Models of Ferron and Sego Sandstones

Michael Farrell and Maija Brown

The ability to make an accurate interpretation of sub-surface reservoirs using seismic data are affected not only by the seismic characteristics (i.e., frequency content, signal-to-noise, trace spacing), but also by the acoustical properties of both the reservoir and non-reservoir facies of the depositional environment. Insights into the interpretation can be provided by comparing forward seismic models of known outcrop data, keyed to depositional environment, to a particular subsurface reservoir. We made detailed, spatially accurate geologic models based on outcrop observations and populated them with rock and fluid properties from analog fields to generate forward seismic models. Multiple modeling runs using different wavelet assumptions, angle stack ranges, signal/noise, fluid properties provides a range of realistic of outputs that are used to help understand the seismic response of a reservoir in an exploration, development and production setting. The resulting modeled seismic data was also post-processed to evaluate how well seismic attributes are correlated with zones of interest. In this study, models were constructed of the deltaic Ferron Sandstone and tidal Sego Sandstone, Utah. Key results of the models show the effects of thin coal beds (low impedance) and cemented zones (high impedance) on seismic imaging of reservoir facies and key stratigraphic surfaces. The models also show to what extent hierarchal stratigraphic elements (parasequence and parasequence sets) are resolved on the data, which can be useful for understanding connectivity issues within deltaic and tidal reservoirs.

AAPG Search and Discovery Article #90156©2012 AAPG Rocky Mountain Section Meeting, Grand Junction, Colorado, 9-12 September 2012