Characterization of Porosity in Black Shales Using Nitrogen Adsorption Experiments and Scanning Electron Microscopy. An Example from The Middle to Late Devonian Horn River Group, Central Mackenzie Valley, Northwest TerritoriesSoapbox Wednesday, November 21, 2018 - 16:30 to 19:00 Multiplex Gym (DND)
Recently, organic-rich shales have become important unconventional reservoirs due to advances in technology that make it possible to exploit hydrocarbons trapped in the pores of these successions. In order to achieve an accurate assessment of the quality of the reservoir, understanding the porosity in these intervals is essential, however, as pores observed in black shales are microscopic, micro-imaging techniques are required to determine pore size, shape, distribution, and total pore volume.
This study focuses on the Middle to late Devonian Canol and Hare Indian formations, black shales of the Horn River Group located in Central Mackenzie Valley, Northwest Territories that have been identified as prospective unconventional resource candidates. Due to the remote location of these intervals, there is relatively few data gathered from the formations in the Horn River Group, and a detailed assessment of porosity has not yet been conducted.
For this project, scanning electron microscopy (SEM) and nitrogen adsorption-desorption experiments are used to characterize pores and determine pore volume. The dataset consists of four samples taken from the Husky Little Bear N-09 well: two from the Canol Formation at depths of 1727.05m and 1718.95m and two from the Hare Indian Formation at depths of 1810.0m and 1825.0m. Using the Barrett-Joyner-Halenda (BJH) model, nitrogen adsorption-desorption experiments suggests that the pore sizes in these samples ranged from 10nm to 100nm. The adsorption-desorption isotherms gathered from the same analysis also indicate that the pores are slit-shaped. The images from the SEM analysis indicate that the pores in these samples can be found in several sites including pyrite framboids, grain boundaries, microfractures, inside grains and in organic matter.
The results of this study contribute to our knowledge of the hydrocarbon storage capacity of the Hare Indian and Canol formations and increase our understanding of their potential as shale reservoirs.