--> Abstract: Sedimentology And Reservoir Architecture Of A Fine-Grained Turbidite System: Lower Triassic Montney Formation, Alberta, Canada, by T. F. Moslow; #90928 (1999).

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MOSLOW, THOMAS F.
Ulster Petroleums Ltd., Calgary, Alberta

Abstract: Sedimentology and Reservoir Architecture of a Fine-Grained Turbidite System: Lower Triassic Montney Formation, Alberta, Canada

Extensive well and core control in the lowstand systems-tract of the Lower Triassic Montney Formation in west-central Alberta has led to the recognition of a higher degree of lateral facies variability and reservoir heterogeneity. In addition, subregional tectonics is recognized as playing a significant role in the distribution, over-thickening and orientation of very fine-grained sandstone turbidite reservoir facies.

A distinct shelf/ramp-"edge" or break-in-slope trends NNW-SSE through the area and defines the up-dip depositional limit of turbidite facies. The ramp-edge orientation is probably fault controlled and marks the onset of rapid and abrupt thickening of the lowstand facies associations. Due to the up-dip headward retreat of turbidite channels, the ramp-edge is highly modified by mass-wasting processes. Turbidite channels bifurcate or trifurcate up-dip towards the ramp-edge, coalesce down-dip towards the base of slope and then grade into turbidite lobes basinward. Turbidite channels are associated with significant lateral discontinuity along depositional strike due to cross-cutting, but have lateral continuity along depositional dip. Turbidite channel facies associations can be amalgamated to thicknesses of 30m, due to synsedimentary tectonism within localized grabens or half-grabens. The distribution of levee-overbank or channel-margin facies associations constrains the width of turbidite channels to a few hundred metres. In addition to inferring proximity, a levee-overbank facies association can be used to infer the direction of the associated turbidite channel through dipmeter log patterns. Turbidite lobes have a broad aerial extent up to a township in size, occur at the down-dip depositional limit of turbidite facies deposition and thin and grade basinward to shaly siltstones.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas