Biostratigraphic and Sedimentological Studies of Natural Gas-Bearing Triassic Strata in the Halfway River Map Area, NE British Columbia

Lead Researcher(s):  J. K. Mortensen

Project ID:  2008-024

Key Research Organization(s):  University of British Columbia

Project Location:  Northeast BC

Strategic Focus Area:  Energy-Oil and Gas


The British Columbia portion of the Western Canadian Sedimentary Basin (WCSB) is far less developed than the Alberta portion. In the past this area has experienced tremendous growth, particularly in natural-gas exploration. Despite this fact many parts of northeastern British Columbia remain significantly under explored due to difficulties in accessibility and a lack of available infrastructure. Triassic clastic strata in this region are among British Columbia's most important reservoir intervals, hosting approximately 37% of British Columbia's conventional gas reserves. The nature and depositional setting of the Triassic succession in northeastern BC, however, have received relatively limited study.

Investigations of Triassic strata farther to the northwest in Yukon Territory has demonstrated that Early and early Middle Triassic units did not accumulate as an easterly derived off-shelf deposit as had previously been thought, but rather formed in a foreland basin setting east of a collisional orogen that developed along the western margin of Ancestral North America in latest Permian time, when the Yukon-Tanana Terrane collided with and began to override the continental margin. Overlying Late Middle and Late Triassic clastic strata in this area appear to represent an overlap sequence that was deposited across both the western edge of Ancestral North America and the collisional orogen to the west. There are hints that a similar tectonic scenario occurred during the deposition of economically important, gas-bearing Triassic strata farther south in northeastern BC. If correct, this would have important implications for the stratigraphic framework of the Triassic units in this area, and for the nature and disposition of potential source and reservoir units.

The proponents of this study carried out a one-year biostratigraphic and provenance study of the Triassic section in the Halfway River map area in northeastern BC. The work was done in conjunction with a geological mapping project that was completed in the area by the Oil and Gas Division of the BC Ministry of Energy, Mines and Petroleum Resources. The main objectives of the study were to provide a much-improved biochronology for the Triassic section in this area, and to evaluate the proposed two-stage depositional model for the deposition of this package.