The Montney Formation is 240 million years old and formed in the early Triassic period. It is situated below the Jurassic/Cretaceous Doig Formation and above the Permian/Carboniferous Belloy Formation. The Montney ranges from Fort St. John, BC and extends to the south-east toward Fox Creek, AB. The north-west region is typically considered "shaley", predominantly "silty" in the Dawson Creek area, and coarser toward Valleyview and Fox Creek. Drilling depth to the Montney follows the same trend in grain size, shallower in Northwest and deeper in the Southeast. The Montney reaches a maximum thickness of ~280 m (920 ft).
What Does It Look Like?
The Montney formation is not a "true shale" due to its high composition of siltstone, but rather considered as a "hybrid", due to the higher content of siliciclastics. Interbedded in the Montney are highly radioactive phosphate layers that can be correlated over much of the Northeast British Columbia basin. These phosphate layers are believed to be the result of rapid rise in sea level, resulting in organic rich layers being deposited over top of fine grained sand and siltstone. These cycles repeat, resulting in a Gamma Ray reading that varies from 150 API to <75 API. Below is an example of a well log showing the distinctive change from the Doig Formation to the Montney.
Oil & Gas Production
Oil is produced from the Western Alberta region of the Montney, where it presents a coarser sandy facies. Natural gas is produced from the gas rich silty shale occurring in the North-Western borders and Dawson Creek/Pouce Coupe Areas. It is estimated that the Montney contains over 50 trillion cubic feet of natural gas.
Shale gas extraction emerged in the late 2000’s where previously it was difficult and uneconomic to produce due to the low permeability. With advancements in hydraulic fracturing and horizontal drilling, reliable and affordable production of natural gas from shale resources is attainable. The chart below outlines the highest gas producing shale formations. Notice that the Montney is 3rd with reserve estimates in excess of 300 trillion cubic feet.
The application of horizontal drilling with aggressive build sections has allowed the borehole greater access to target reservoirs. The utilization of horizontal drilling applications with open hole evaluations and multi-stage fracture sequences and has helped show the lucrative potential of the Montney Formation.