--> Exshaw Formation Study, Liard Basin, Northwest Territories, Canada

AAPG Annual Convention and Exhibition

Datapages, Inc.Print this page

Exshaw Formation Study, Liard Basin, Northwest Territories, Canada

Abstract

The Liard Basin covers an area of 8,400 sq. km. and straddles the Northwest Territories (NT), northeastern British Columbia (NEBC), and the Yukon (YK) borders. Unconventional shale gas exploration was first initiated in the NEBC portion of the Liard Basin in approximately 2009 where the exploration focus was on the organic rich, black shale of the Exshaw Formation (Fm.) A tri-jurisdictional resource assessment of the Exshaw Fm. in the Liard Basin was initiated in 2015 by the Northwest Territories Geological Survey (NTGS), the BC Ministry of Natural Gas Development, the National Energy Board (NEB) and the Yukon Geological Survey (YGS). The purpose of this paper is to present the results of the NTGS study of the Exshaw Fm. in the NT portion of the Liard basin. The Exshaw Fm. stratigraphy was established using core and logs from the Patry b-23-K well (Ferri et al., 2015). In BC, this interval is comprised of three units: Upper Exshaw, Lower Exshaw and the Patry. Regional cross sections were constructed and tied to the Patry b-23-K well to establish a stratigraphic framework for the Exhaw Fm. throughout the study area. A comprehensive suite of maps and data were compiled for the resource assessment. These include the following: depth of formation, gross and net shale isopachs (using a 10 Ωm cut-off) and bottom-hole temperature. Calculated parameters that were not mapped include wt% TOC, estimated temperature and pressure gradients. In the NT part of Liard Basin, the Exshaw Fm. is up to 303m thick and averages 3.35% TOC. In general, it is thickest to the south near the BC border and thins northwards. The isopach also thins dramatically at the Bovie Structure, the easternmost extent of Liard Basin. Using the aforementioned resistivity cut-off, net pay is up to 270m thick. The Patry member can be correlated into the Northwest Territories as far as 60.6°N. At Bovie Structure it is absent and is considered to correlate with part or all of the Kotcho Formation. The average temperature and pressure gradients are 0.0411°C/m and 8.81kPa/m, respectively. Reference Ferri, F., McMechan, M., and Creaser, R. 2015. The Besa River Formation in Liard Basin, British Columbia. In: Oil and Gas Geoscience Reports 2015, British Columbia Ministry of Natural Gas Development, pp. 1-27.