Slope Terrains:
A Critical Factor in Explaining and Predicting the Distribution and Type of
Slope Reservoirs
Donovan, Art1 (1) BP,
Two fundamental first-order controls
(delta position & slope terrains) can be used to better explain and predict
both the type and distribution of slope reservoir systems (leveed, vs.
confined, vs. sheet). Delta position controls the sediment entry points into
the basin. Off-axis areas offer limited opportunity for slope reservoirs. Slope
terrains, which are herein termed Simple, Chute, Ponded, and By-pass, are
controlled by the rugosity of the slope, as well as the size of the slope
channels (gullies vs. canyons). These terrains determine the architectures of
dominant turbidite reservoir types deposited on slopes down-dip of the deltaic
depocenters.
Simple Terrains form on slopes with
limited to no rugosity. Because of the lack of rugosity, slope channels are
free to move laterally across the slope and do so predominantly as Leveed
Channel Complexes. Chute Terrains form due to two-dimensional confinement
between salt and/or shale structures in areas of moderate rugosity. The
structural movement in these areas leads to lower relief slopes and the
development of confined channel complexes confined to the two-dimensional lows.
Ponded Terrains form in response to three-dimensional confinement between salt
and shale structures in areas of the slope with high rugosity. The structural
movement in these areas leads to localized lows and the development from time
to time of sheet complexes in ponded lows. By-pass Terrains form when a large
canyon develops across the slope. These canyons form efficient by-pass systems
that move turbidites from the shelf margin to basin floor drastically reducing
reservoir potential of the slope.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California