Charles M. Henderson1
(1) University of Calgary, Calgary, AB
Abstract: A Lower Triassic Montney Formation sharp-based shoreface play in a tectonically active region of northwestern Alberta
The Lower Triassic Montney Formation in the Peace River Embayment area of northwestern Alberta is of great interest to hydrocarbon exploration companies. previously the Montney was considered a secondary target, but in recent years has become a primary exploration target. One reason for this is the large underexplored region of the Peace River, where statistically 50% of Triassic reserves remain undiscovered. Hydrocarbon production is almost completely restricted to Dienerian and Smithian age lithofacies with minor production from older Griesbachian and younger Spathian age reservoir lithofacies.
The primary Montney play type that has sparked considerable interest, especially when hydrocarbon prices were low, is a nearshore/shoreface reservoir play. this oil and gas play is relatively shallow (900-1300m) and therefore economic. the main lithofacies of this play are fine-grained sandstones and dolomitic bivalve and inarticulate brachiopod coquinas.
The Lower Montney Griesbachian age sharp-based shoreface sandstone was encountered in the southern part of the study ara and is found up to 20 m above Permian age rocks. Sharp-based shoreface successions are usually ascribed to a eustatic fall, but global sea level charts do not show a corresponding fall. Perhaps this succession is generated tectonically as it is restricted to the downthrown side of structural highs. Early results show that this Griesbachian age sandstone is restricted to the structurally lower side of possible syntectonic paleohighs and is a good potential reservoir lithofacies with well-sorted, fine-grained quartz and dolomite grains leading to intergranular porosities up to 30%.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana