--> Abstract: The Montney Formation of West-Central Alberta: Prolific Turbidite Play in a Hydrocarbon Mature Basin, by Thomas F. Moslow and John-Paul Zonneveld; #90039 (2005)

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The Montney Formation of West-Central Alberta: Prolific Turbidite Play in a Hydrocarbon Mature Basin

Thomas F. Moslow1 and John-Paul Zonneveld2
1 Midnight Oil and Gas Ltd, Calgary, AB
2 Geological Survey of Canada, Calgary, AB

Fine-grained turbidite reservoirs of the Lower Triassic Montney Formation became the Western Canada Sedimentary Basin's most active exploration play in the early 1990's. Since its discovery, over 1.5 TCF of recoverable liquids-rich gas have been assigned to this play, making it one of the largest recent discoveries in the basin.

Due to lack of evidence supporting abyssal paleo-water depths, initial interpretations of the Montney as a turbidite succession were met with skepticism. Although deposited in water depths not exceeding a few hundred meters, sedimentologic observations from core and outcrop provide the basis for interpretation of the fine-grained sandstone to coarse siltstone Montney reservoirs as a ramp turbidite succession. Deposition was strongly influenced by extensional tectonics resulting in rapid lateral facies variability and reservoir heterogeneity.

Turbidite sandstones occur in outcrop of the Sulphur Mountain Formation at a stratigraphic level correlatable to principal reservoir horizons in the Montney Formation approximately 100km basinward of the terminus of existing production. Despite this, most exploration has ceased near the Alberta – British Columbia border principally due to a lack of infrastructure and economic success. Limited well penetrations and core control at the basinward fringes of the play have encountered intervals of turbidite facies with low sand/shale ratios and thus log porosities of approximately 6-9%. Outcrop data provide crucial constraints on the presence and trend of turbidite facies in the under-explored basinward margin of the play where limitations of existing reservoir models are due to reliance on well logs and limited cores from relatively widely spaced wells.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005