Discrete dilatant pathway modeling of gas migration through compacted bentonite clay

Kim, Kunhwi; Rutqvist, Jonny; Harrington, Jon F.; Tamayo-Mas, Elena; Birkholzer, Jens T.. 2021 Discrete dilatant pathway modeling of gas migration through compacted bentonite clay. International Journal of Rock Mechanics and Mining Sciences, 137, 104569. 10.1016/j.ijrmms.2020.104569

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Abstract/Summary

A coupled multiphase fluid flow and discrete fracturing model is applied to simulate bench-scale gas migration experiments on compacted bentonite. The numerical modeling is based on the linking of the multiphase fluid flow simulator TOUGH2 with a Rigid-Body-Spring Network model, which enables a discrete (lattice) representation of elasticity and individual fractures. The evolution of a complex network of dilatant flow paths is modeled through opening and breakage of lattice interface bonds between porous-elastic matrix elements. To achieve a good match with the experimental results, including an abrupt gas breakthrough along with pressure and stress responses, it was necessary to calibrate model parameters for (1) air-entry pressure, (2) shear and tensile failure of lattice interface bonds, (3) moisture swelling/shrinkage effects on stress, and (4) aperture-dependent permeability of dilatant flow paths. Our best-fit conceptual model considers a pervasive network of discrete flow paths propagating from the gas injection point, whereas some of the experimental data indicate the potential for heterogeneous and unstable flow paths.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.ijrmms.2020.104569
ISSN:	13651609
Date made live:	13 Apr 2021 12:36 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/530045

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