Seismic Forward Modeling of an Asymmetric Deltaic Outcrop Reservoir Analog: Ferron Notom Delta, Utah
Outcrop studies can provide fine scale geological information which is critical for precise subsurface reservoir modeling. Synthetic seismic modeling is a useful tool to bridge outcrop and actual seismic data. It enables the link between the internal architecture and facies distributions of outcrop and their possible seismic responses of the subsurface.
The Cretaceous Ferron Notom Delta complex is interpreted as ancient asymmetric wave-influenced delta. Measured sections are interpreted as typical shore facies along the dip direction and river-dominated delta front facies along the strike direction. In this study, seismic responses of the updrift cross section and downdrift cross section are modeled and compared at different frequencies and burial depths. The comparison of synthetic seismic images indicates that shorefacies and river-dominated delta front facies at Notom scale may be able to be differentiated in actual seismic dataset. Then the seismic expressions of the distributary channels are modeled. The result shows that most of distributary channels (about 90%) cannot be imaged by conventional seismic survey. The clinoform (or clinothem) concept is deployed to describe deltaic-related successions widely in shallow marine depositional systems. At last, the seismic expressions of clinothems are modeled and the effects of petrophysical properties (porosity, shale proportion, density, velocity) trend within clinoforms on seismic response also are investigated. It was shown that the stratigraphic complexity of Notom delta can only be seen at very high frequency seismic dataset (>120Hz at 2000m deep). This further demonstrated that the outcrop study will provide valuable sub-seismic information for reservoir study. Seismic modeling of Ferron Notom delta can provide a valuable analog for seismic interpretation of deltaic reservoirs.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California