Depositional architecture of the Cadomin and Monteith formations, north east British Columbia

In the Aitken Creek area of northeastern British Columbia, the uppermost Jurassic and lower Cretaceous section is divided into the Minnes and Bullhead Groups. The quartzose sands of the Monteith Formation (Minnes Group) and the chert rich sands of the Cadomin Formation (Bullhead Group) have been subjected to stratigraphic and sedimentologic analysis. These formations were deposited in a non-marine, braidplain environment throughout the study area. Despite similar depositional histories, these formations are separated by a basin wide unconformity. The braided fluvial system of the Monteith Formation is localized in northeastern British Columbia, while the Cadomin system is more widespread across northeastern British Columbia and Alberta.; Permeability and ultimate reservoir potential for these sandy braidplain sediments is controlled by primary depositional textures, mineralogy, secondary enhancement, and diagenetic modifications that have occurred during burial and compaction. The major reservoir limiting factors include silica cementation, residual bitumen occluding pore spaces, and the presence of detrital and authigenic clays. A secondary pore-system was developed by fracturing and through the leaching of grains by pore fluids, thereby increasing permeability. In northeastern British Columbia, both structural and stratigraphic traps exist within the Monteith and Cadomin Formations. A fundamental understanding of all these factors is needed to locate and exploit economic reservoir quality rocks in these braidplain sediments.