Modelling the Devonian Horn River Group of central NWTOnline pre-recorded
The Middle to Upper Devonian Horn River Group in the central Northwest Territories has been extensively studied by the Northwest Territories Geological Survey (NTGS), the Geological Survey of Canada (GSC), and the energy industry. The resulting datasets, including publicly available well files, survey reports, and outcrop and well sample data, are used in this study for the creation of local and regional geological models. The main objective of this project is to use these models to better understand the regional hydrocarbon system present in the Mackenzie fairway. The models will help to determine how the resource was generated, subsequently migrated, and accumulated at its present location.
The study area includes the Mackenzie Plain Region and adjacent swathes of the Peel Plateau, Peel Plain, Franklin Mountains, and Mackenzie Mountains. For this project 584 wells and 30 outcrops with data were considered as input for the geological models. In the initial phase of the project, well and outcrop data were assessed and those with insufficient or low-quality data were discarded. In the case of overlapping wells, the most recent well with a full lithological report was selected. The selected data were formatted into point models at the scale of individual wells or outcrops. Lithology for each formation was entered as a percentage of major lithological components (% sandstone, shale, siltstone, etc.). For the creation of these local-scale models, certain regional assumptions based on best available knowledge were used, including: timing of unconformities, the total thickness of erosion along those surfaces, and an estimate of the regional heat flow. Based on values from previous research by the GSC, the major regional erosional surfaces are the sub-Cretaceous unconformity (estimated 2.5 km to 3.5 km of erosion), sub-Slater River erosion (135 m), and end Little Bear erosion (75 m). For the regional heat flow, a value of 80 mW/m2 was used.
Calibrating the resulting well and outcrop models using maturity data, commonly vitrinite reflectance, has provided reasonable correlations between simulated depth vs maturity curves and sample results. These models will be incorporated into the regional 3-D model, which will be used to simulate hydrocarbon generation, migration, and accumulation. A preliminary build of the geological model using a limited set of local models added to seismic-derived surfaces and a topography map has highlighted important technical issues that will need to be resolved before the full dataset can be added.