--> ABSTRACT: Multi-Storey Sandstone Bodies, Sequence Stratigraphy, and Fluvial Reservoir Connectivity, by D. K. Larue, A. R. Sprague, P. E. Patterson, J. C. Van Wagoner; #91020 (1995).

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Multi-Storey Sandstone Bodies, Sequence Stratigraphy, and Fluvial Reservoir Connectivity

D. K. Larue, A. R. Sprague, P. E. Patterson, J. C. Van Wagoner

Four end-member types of fluvial multi-storey sandstone bodies are recognized in outcrop studies and have been modelled numerically in 3-D. These are here informally labelled: 1) channel-fill complexes; 2) aggradational sheet complexes; 3) channel-fill belts; and 4) multi-storey complexes consisting of genetically-unrelated channel deposits (that is, channel deposits that "randomly" intersect in 3-D). The four types of complexes are differentiated on the basis of: a) presence of floodplain deposits within the multi-storey body (channel-fill belts, genetically-unrelated complexes) versus absence to rareity (channel-fill complexes and aggradational sheet complexes); b) disordered arrangement of channels (genetically-unrelated complexes) versus ordered arrangement (channel-f ll complexes, channel-fill belts and aggradational sheet complexes); c) presence of laterally and vertically interconnected channel-fill deposits, overlying a single master erosion surface (channel-fill complex) versus multi-storey sandstone bodies characterized by relatively planar and erosive basal contacts, and internally containing thick bar-form deposits (aggradational sheet complexes). Channel-fill belts are similar to channel-fill complexes but lack a single basal master erosion surface and contain intercalated floodplain deposits. Reservoir connectivity is best for channel-fill complex deposits and aggradational sheet complexes, and slightly worse for channel-fill belt deposits (largely due to the presence of floodplain deposits within the complex) and worst for the disordered ge etically-unrelated complexes.

The first two types of multi-storey sandstones (complexes and sheets) are characteristic of lowstand systems tract deposition. Channel-fill belts are characteristic of transgressive and highstand systems tract deposition, whereas genetically-unrelated complexes could in theory be associated with any systems tract. Future geologic models of fluvial reservoirs should incorporate both sequence stratigraphic architecture and different types of multi-storey sandstone bodies, because there is a direct relationship between the nature of the multi-storey sandstone body, the sequence stratigraphic architecture, and reservoir connectivity.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995