(1) Elf Exploration Angola, Roissy Cedex, CDG, France
(2) University of Texas, Arlington, TX
(3) Southampton Oceanography Center, Southampton, United Kingdom
Abstract: Recent deep-sea fan meander channelforms as analogs for similar prospective subsurface fans
We present here a synthesis of recent fan meander channelforms as revealed by side-scan imagery, high-resolution 2D seismic and coring. The most important features of these channelforms, are sinuosities up to 3.0, vertical aggradation and lateral channel migration on various scales, channel avulsion and branching, and cutoff meanders. These sinuous channelforms and the associated features have commonly reservoir-prone lithologies. Also, the overbanks of low-relief sinuous channels in the distal areas of the fan are sand-prone although those of high-relief channels in the proximal areas are shale-prone. A variety of lobeforms occurs in association with these high sinuous channels-at their termini and their bends. The lobeforms at the channel bends consist of 'washover fans' and several types of crevasse-splays. the type of these lobeforms depends on the depth of the thalweg of the main channel, the depth of levee-breaching, the gradients, leading to the adjacent basinal areas, and the energy of sediment-gravity flows. Many of the lobeforms have commonly straight channels of varying dimensions and consist of channel fills, overbank deposits and several attached, relatively small lobes and splays in varying proportions, and their reservoir geometry and continuity may be complex.
Sinuous channelforms and associated features, very similar to those of recent fans, have been observed in the prospective subsurface fans and are similarly reservoir-prone. Therefore, the recent fan meander channels can be used as analogs to better predict the reservoir geometries of their subsurface counterparts. However, lack of 3D seismic data on recent fans precludes a precise knowledge of temporal evolution and architecture of sinuous channels and associated lobeforms.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana