--> ABSTRACT: Lobe and Sheet Depositional Forms Associated with Deepwater Sinuous Channels, by Venkata Kolla, C. H. Ould Ahmed Benan, P. Bourges, Henry Posamentier, and J. E. Damuth; #90906(2001)

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Venkata Kolla1, C. H. Ould Ahmed Benan2, P. Bourges3, Henry Posamentier4, J. E. Damuth5

(1) Consultant, Houston, TX
(2) Total Fina Elf, Paris, France
(3) Elf Exploration Angola, Luanda, Angola
(4) BP Indonesia, Houston, TX
(5) University of Texas at Arlington, Arlington

ABSTRACT: Lobe and Sheet Depositional Forms Associated with Deepwater Sinuous Channels

Sidescan imagery, 2D and 3D seismic, and coring of recent and subsurface deepwater fans in several parts of the world show a variety of lobe- and sheet depositional forms genetically related to sinuous channels. These depositional forms occur adjacent to channel sinuous bends or at the channel termini. The lobeforms adjacent to the channel bends consist of 'wash over fans', and several types of crevasse-splays; the type and occurrence of these lobeforms depends on the depths of the thalweg and levee-breaching of the parent channel, the gradients leading to the adjacent basinal areas, the energy of sediment-gravity flows and the type of sediment input. With only overbank spilling and flow stripping, washover fans form. With shallow to moderate levee-breaching and mixed sediment type, crevasse-splay lobeforms, with channels, form. With deep levee-breaching and more sand-rich input,'harps'- type lobeforms occur in adjacent basinal areas. All lobeforms adjacent to channel bends are sand-prone, but the net-to-gross values are the highest in the 'harps'. The lobeforms at the channel termini consist of either single lobes or several lobes that coalesce to form a lobe complex. They commonly have channels and have high net-to-gross values. All types of lobeforms, that have no channels within them (washovers, 'harps', and channel-terminus lobeforms), have good lateral and poor-to-good vertical reservoir continuities. However, the lobeforms, with channels consist of multiple channel fills, overbank sheet deposits and several channel-attached, small lobes and splays, and may have complex reservoir architecture.

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