--> The Montney Turbidite Complex of Northwest Alberta and Northeast British Columbia: Evolution of an Oil and Gas Play From Conventional to Unconventional

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The Montney Turbidite Complex of Northwest Alberta and Northeast British Columbia: Evolution of an Oil and Gas Play From Conventional to Unconventional

Abstract

The Lower Triassic Montney formation is one of western Canada's most lucrative unconventional hydrocarbon plays. With a thickness in excess of 300m, aerial extent covering approximately 130,000 km2, the National Energy Board of Canada estimates the Montney Formation contains marketable resources of 449 TCF of gas, 14.5 billion barrels of NGL's and 1.13 billion barrels of oil. The Lower Montney Formation in the Peace River Arch region of northwest Alberta and northeast British Columbia was one of the first areas of the Montney exploited for hydrocarbon beginning in 1980. The initial discoveries were made in turbidite channel complexes, using 3D seismic and conventional vertical drilling and completion methods. The reservoir are highly porous (15%) and permeable (1-5 md) fine grained channel sands. The channels facies is very prolific but limited in aerial extent. Beginning in 2006, with the advent of horizontal drilling and multi-frac completion technology, it now became possible to economically exploit the thicker more aerial extensive, fan portion of the turbidite complex. These rocks are fine grained laminated siltstones with lower porosity (3-10%) and lower permeability (less than 0.1 md) but, extremely thick (30-70 m). Detailed geological mapping reveals that the deposition and the thickness of the fan is structurally controlled by underlying Paleozoic fault systems that define the Fort St. John graben complex. Isotope geochemistry of the hydrocarbons reveals that they are internally sourced, and their distribution display a normal thermal maturity distribution with dry gas being found in the deepest portion of the basin, transitioning to wet gas condensate and light oil concentrated along the basin margin. The fan can be mapped into 3 cycles ranging in thickness of 15m to 25m. Each cycle has a preferred landing zone which contains more highly porous and permeable rock which local operators target. Thru time the more proximal portion of the fan has been exploited but with the further advancement of drilling and completion techniques, more distal portions of the fan complex are economically being exploited.