Swelling effect on coal micro structure and associated permeability reduction
MetadataShow full item record
© 2016 Elsevier Ltd. All rights reserved.Porosity and permeability of deep unmineable coal seams are key parameters in the context of (enhanced) coalbed methane recovery and CO2 geo-storage in coal beds as they determine productivity and injection rate. Porosity and permeability are again determined by the micro-structure of the coal, and the cleat network-coal matrix system. Furthermore, it is well established that swelling of the coal matrix due to water adsorption can significantly reduce permeability. However, the exact effect of swelling due to water adsorption on the coal micro-structure is only poorly understood, and how this microstructural change impacts on the permeability and porosity characteristics of the coal. We thus imaged dry coal plugs and swollen coal plugs (swollen due to brine adsorption) at high resolution (3.43 µm3) in 3D with an X-ray micro-computed tomograph (microCT). On the microCT images two types of cleats were identified; cleats in the coal matrix and cleats syngeneic with the mineral phase. Approximately 80% of the coal matrix cleats closed upon water adsorption, while the cleats in the mineral phase were not affected. This cleat closure by water adsorption dramatically reduced porosity and particularly permeability, consistent with dynamic permeability core-flood measurements.
Open access to this article is currently embargoed until 10 06 2018
Showing items related by title, author, creator and subject.
Estimating cleat characteristics in reservoir simulation models of coal seam gas reservoirs using welltest analysisBahrami, N.; Byfield, R.; Hossain, Mofazzal; Chitgar, A.; Wong, J. (2015)Copyright 2015 Society of Petroleum Engineers.Coal Seam Gas reservoirs are naturally fractured and the flow of fluid throughout the coal occurs by diffusion through the coal matrix and then via the cleats (network of ...
Experimental study on physical structure properties and anisotropic cleat permeability estimation on coal cores from ChinaXu, X.; Sarmadivaleh, Mohammad; Li, C.; Xie, B.; Iglauer, Stefan (2016)Knowledge of the natural structure properties of coal seams is essential for the coal bed methane (CBM) production because of their great influence on the inner flow characteristics and permeability features of hydrocarbons ...
Multi-scale x-ray computed tomography analysis of coal microstructure and permeability changes as a function of effective stressZhang, Yihuai; Xu, X.; Lebedev, Maxim; Sarmadivaleh, Mohammad; Barifcani, Ahmed; Iglauer, Stefan (2016)© 2016 Elsevier B.V. Gas permeability (k) and porosity (f) are the most important parameters in CBM/ECBM and CCS in deep unmineable coal seams. k and f depend on the coal microstructure, and k and f significantly change ...