Minken, Jon1, Roger Slatt1, Henry Posamentier2
(1) University of Oklahoma, Norman, OK
(2) Anadarko Canada Corporation,
ABSTRACT: Erosional Remnants in Deep-Water Channel Systems: Outcrop and Subsurface Characterization
Erosional remnants observed in deep-water channel systems form as a result of multiple episodes of channel migration and incision. Observed geometries are highly irregular with pinches and swells along depositional dip due to lateral incision of parallel channels. Internally, the lithology of the erosional remnants are independent of that of the incising channel, but rather a function of the strata eroded by the channel.
3D seismic volumes of the deep-water Triassic Montney Formation, western Canada, and Pleistocene sediment-gravity flows from the DeSoto Slope, northern Gulf of Mexico both exhibit erosional remnants in association with channel fills. In both 3D seismic volumes, the erosional remnants are high-amplitude features composed largely of dissected frontal splays. Channel-fills flanking these remnants are characterized by low amplitude seismic reflections and are interpreted as mainly shale.
Erosional remnants have been identified in outcrops of the Cretaceous Dad Sandstone Member, Lewis Shale, Wyoming. Detailed measured sections and Ground Penetrating Radar (GPR) images illustrate the external form and internal complexity of these features. In contrast with the Montney and Gulf of Mexico examples, these erosional remnants are fine-grained, thinly-bedded, dissected levee/overbank sandstones and siltstones. The associated channel fills are sand-prone with the uppermost fill onlapping the remnant, indicating a hiatus between deposition and erosion.
These examples document the internal complexity of the remnants, the geomorphology of such features and the overall complexity they add to this environment. In a channel-dominated reservoir succession, erosional remnants can compartmentalize sands and give rise to tortuous fluid flow paths. They are an important element of the deep-water channel model, and should be considered in reservoir modeling and management planning.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.