Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8123708 | International Journal of Coal Geology | 2016 | 8 Pages |
Abstract
Gas permeability (k) and porosity (Ï) are the most important parameters in CBM/ECBM and CCS in deep unmineable coal seams. k and Ï depend on the coal microstructure, and k and Ï significantly change with varying effective stress. However, how the coal microstructure is related to such permeability and porosity changes is only poorly understood. We thus imaged sub-bituminous coal samples at two resolutions (medium - 33.7 μm and high - 3.43 μm voxel size) in 3D with an x-ray micro-computed tomography as a function of applied effective stress; and investigated how cleat morphology, k and Ï are influenced by the changes in effective stress and how these parameters are interrelated. In the images, three phases were identified: microcleats (void), a mineral phase (carbonate) and the coal matrix. When effective stress increased, the cleats became narrow and closed or disconnected. This resulted in a dramatic permeability drop with increasing effective stress, while porosity decreased only linearly.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Economic Geology
Authors
Yihuai Zhang, Xiaomeng Xu, Maxim Lebedev, Mohammad Sarmadivaleh, Ahmed Barifcani, Stefan Iglauer,