The Lower Triassic Montney Formation of the Western Canada Sedimentary Basin is a World-class resource with 450 TCF of gas reserves, 14,520 MMBBL of natural gas liquids reserves and 1,125 MMBBL of oil reserves. Resources are primarily hosted in organic-rich and organic-lean low-permeability siltstones and to a lesser extent, very fine-grained silty sandstones. Distal portions of Montney fans contain well-sorted siltstones and clay-rich shales in various proportions. At a certain part of the paleo-basin, they are also intercalated with organic-rich (anoxic) shales, forming a hybrid “sweet-spot” for the play. Deposition of the distal turbidite sequences took place in an anoxic - dysoxic environment, with several periods of higher oxygen levels. The environment of deposition is related to pore structure and amount of three porosities: nano-pores associated with kerogen, micro-pores of clay minerals, and intergranular micro-pores of siltstones. Organics composed of type I/II oil- prone kerogen are responsible for hydrocarbons and overpressure generation; Siltstones – providing storage space and sufficient matrix permeability (higher than average in typical self-sourced unconventionals); and finally, Clay-bound water acts as a local capillary-pressure seal.
Montney turbidites are 500-900 ft thick, covering area of approximately 130,000 sq km, and even with low porosity (6%) and rather low recovery (<10%), presenting a very attractive target showing enough resilience to “commodity price volatility”.
References
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