--> Abstract: Development of Reservoir Models for Sandy Braided Rivers Using Modern Analogues; #90063 (2007)

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Development of Reservoir Models for Sandy Braided Rivers Using Modern Analogues

 

Lunt, Ian A.1, Greg H. Sambrook Smith2, Phil J. Ashworth3, James L. Best4, John S. Bridge5, Stuart N. Lane6, Chris J. Simpson7, Rob E. Thomas1 (1) University of Leeds, Leeds, United Kingdom (2) University of Birmingham, (3) University of Brighton, (4) University of Illinois at Urbana-Champaign, (5) Binghamton University, (6) University of Durham, (7) Simon Fraser University,

 

The South Saskatchewan River has been associated with many facies models of braided river deposits since the work of Cant and Walker in the late 1970's. In a new, long-term study, an 18 km reach of the South Saskatchewan has been investigated in detail using i) coring, ii) ground-penetrating radar profiles that penetrate up to 5m below the river bed, and iii) sequential aerial photography taken every 6 months (enabling photogrammetrically-derived DEM's to be constructed over the entire channel belt). The study coincided with a 1 in 50 year flood event, which allowed the impact of an extreme discharge event on the sediment deposits to be examined. Importantly, this dataset shows explicitly how fluvial deposits are constructed by individual bedforms (e.g. dunes, unit bars, compound bars) and channel fills, and how these deposits may be preserved in the rock record.

 

In particular, the dataset allows the preserved 3-D deposit dimensions to be related to formative bedform geometry. Our findings show that preserved bar-deposit thickness is ~50% of the original bar height, and lengths are ~25% of formative bar lengths. In addition, the unit bar lengths scale directly with channel width. This information allows development of quantitative scaling relationships to predict sub-seismic scale deposit dimensions and their spatial distribution. The high-resolution GPR and core information were used to generate a pseudo-reservoir model that shows the high degree of spatial heterogeneity within these deposits. Strategies for incorporating scaling relationships, such as those determined from the South Saskatchewan River study, into rule-based geological models will be presented.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California