Publication Date:
2008-04-01
Description:
Net transgressive sandstones form a significant component of many shallow-marine reservoirs, but their shale-poor character commonly masks complex facies architecture and stratigraphy associated with significant permeability variations that impact reservoir drainage patterns and ultimate recovery. In this article, the controls on net transgressive sandstone reservoir architecture are investigated through a detailed analysis of the Cretaceous Hosta Tongue of the Point Lookout Sandstone (informally termed Hosta sandstone in this article) outcrop in New Mexico. Mapping of facies architecture within a series of adjacent canyons has enabled a quantitative three-dimensional reconstruction of key stratigraphic surfaces and sand body distributions from an updip pinch-out to a downdip pinch-out of the net transgressive sandstone complex. The Hosta sandstone contains a complex arrangement of wave- and tide-dominated facies associations arranged in an overall transgressive pattern. Tidal channel-fill sandstones, tidal sheet-form sandstones, and heterolithic tidal-flat and lagoonal deposits comprise the stratigraphy in the updip part of the system. These deposits pass abruptly downdip into wave-dominated shoreface sandstones. The facies composition indicates that the Hosta sandstone represents a wave-dominated barrier shoreline and a tide-dominated back-barrier lagoon. Facies associations are partitioned both vertically and laterally by a hierarchy of transgressive erosion (ravinement) surfaces cut by wave and tidal processes. Reconstructing the geomorphology and spatial organization of these surfaces is critical to understanding sand body distribution and facies architecture at high-resolution (intrareservoir) scale. The exceptional quality of the Hosta Sandstone outcrops has enabled (1) improved understanding of patterns and controls of facies architecture in net transgressive sandstone reservoirs, (2) construction of predictive templates of facies architecture in interwell volumes, and (3) quantification of geobody dimensions and spatial distribution patterns. In combination, these data provide appropriate qualitative and quantitative conditioning for reservoir models. Peter Sixsmith is currently working as a stratigrapher with Chevron. He earned a B.Sc. degree in geology and physical geography (1996) and a Ph.D. in sedimentology and sequence stratigraphy (2000), both from the University of Liverpool. The research for this article was conducted as part of a postdoctoral research at Imperial College London. Gary Hampson is a senior lecturer in sedimentary geology at Imperial College London. He earned his B.A. degree in natural sciences from the University of Cambridge (1991) and his Ph.D. in sedimentology and sequence stratigraphy from the University of Liverpool (1995). His research interests lie in the understanding of siliciclastic depositional systems and their preserved stratigraphy, and in applying this knowledge to reservoir characterization. Sanjeev Gupta is a reader in sedimentology at Imperial College London. He graduated from Oxford University in 1987, where he also conducted his doctoral research (1995). His research interests include controls on sedimentation and stratigraphy in foreland and extensional basins, and field and modeling studies of shore-zone depositional systems. Howard Johnson is the Shell Professor of Petroleum Geology at Imperial College London. He holds a B.Sc. degree in geology from the University of Liverpool and a D.Phil. in clastic sedimentology from the University of Oxford. His main research interests are in clastic sedimentology, sequence stratigraphy, and reservoir characterization. John Fofana earned his B.Sc. degree in geology from Birkbeck College, University of London (2002), and undertook an M.Sc. degree in petroleum geoscience at Imperial College London in 2003–2004.
Print ISSN:
0149-1423
Electronic ISSN:
1943-2674
Topics:
Geosciences
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