The intra-continental Queen Charlotte Basin succession is composed of three principal tectono-stratigraphic packages. The oldest is the Wrangellian succession, comprised of a thick sequence of Upper Triassic and Lower Jurassic carbonates, siliciclastics, shales and siltstones deposited in a stable shelf setting. The unconformable Cretaceous mid-succession is a series of coarse clastics, siltstones and shales with limited source but significant reservoir potential. The unconformable third succession is composed of 2000 m of Neogene volcanics and up to 6000 m of Mio-Pliocene clastics, shales and coals that offer some source yet excellent reservoir potential in the Skonun Formation. Migration and maturation occurred during the Pliocene.
Eight offshore wells were drilled in the region during the late 1960’s, before imposition of the 1972 exploration moratorium. Primary objectives focussed on Miocene clastics in an anticlinal setting, although three wells penetrated Cretaceous section immediately overlying Triassic volcanics. These data are combined with modern 40-fold seismic profiles to determine: 1) distribution of late Triassic to mid- Jurassic source rocks; 2) distribution of Albian- Cenomanian clastics of the Haida reservoir rocks; and 3) petroleum potential of the largely untested deeper section.
Key to the future of Queen Charlotte Sound and Hecate Strait as a significant petroleum- producing province is an understanding of the distribution of the Wrangellian Kunga and Maude as well as the Cretaceous Haida. Uplift and erosion in the Cretaceous to early Tertiary resulted in removal of significant portions of these important source and reservoir rocks.