Controls from Gravel Deposits in Deep-Water Reservoirs; Bedload Transport and Bedforms Associated with Turbidity Currents
Outcrops show features indicating that turbidity currents transport both sand and gravel as bedload (in traction). In addition, both outcrops and the modern seafloor show evidence for a variety of bedforms, including dunes, antidunes and cyclic steps. Lacking better information, most researchers have interpreted these features using relations based on rivers and experimental models of fluvial flow. Here the results of a series of experiments on bedload transport by saline underflows and turbidity currents are presented. In the case of the saline underflows, dissolved salt is a surrogate for fine mud in suspension that does not easily settle out. The experiments indicate that the relation for bedload transport for such currents is very similar to that obtained for rivers. In addition, the experiments revealed four regions for bedforms: plane mobile bed, upstream-migrating antidunes, downstream-migrating antidunes and dunes. These results are applied to an outcrop showing sediment waves in gravel, as well as gravel waves on the modern seafloor. They are of particular relevance to the interpretation of gravel-bearing hydrocarbon reservoirs.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009