Venkata Kolla¹, Henry W. Posamentier²

(1) Consultant, Houston, TX
(2) Veritas Exploration Services, Calgary, AB

ABSTRACT: Similarities and Differences between Deepwater and Fluvial Meander Channels

Fluvial and deepwater meander channels are similar in high sinuosities and their variations with valley gradients, and in relationships between meander wavelength and both channel width and radius of meander curvature, and seismically expressed crescent-shaped amplitude fields within meander loops. There are, however, significant differences between these channels. The widths and depths of deepwater channels generally decrease down-systems in contrast to the opposite trends in fluvial channels. Meander cutoffs are less common and avulsions more frequent in deepwater channels compared to fluvial channels. The strata in the gross depositional fill within the meander loop present an off-lapping character with relatively flat top in the fluvial case, and uplapping or uplapping/offlapping character with top aggrading from convex to concave side in the deepwater case. In deepwater channels lateral migrations may be either discrete, separated from each other in distance or continuous, as seen on seismic whereas in fluvial channels they are continuous. The similarities suggest that both deepwater and fluvial channels become highly sinuous in an attempt to establish equilibrium conditions. The differences, however, show that the precise modes of accomplishing increased sinuosities are different in deepwater and fluvial channels and result from differences in the hydrodynamic characteristics unique to each environment. We discuss these modes of sinuosity evolution and their implications to the reservoir architecture of deepwater sinuous channels as contrasted with that of fluvial channels.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado