Coupled chemo-mechanics of evolving permeability in geomaterials

TitleCoupled chemo-mechanics of evolving permeability in geomaterials
Publication TypeJournal Article
Year of Publication2011
AuthorsLB Hu, and T Hueckel
JournalComputational Geomechanics, Comgeo Ii Proceedings of the 2nd International Symposium on Computational Geomechanics
Start Page599
Pagination599 - 608
Date Published09/2011
Abstract

Flow of fluids in geomaterials may be strongly affected by chemo-mechanical processes, which are either externally induced or spontaneous. This is the case when dissolution, transport of the dissolved mineral and its precipitation in the neighborhood pore space causes a decrease of what is upscaled as Darcian permeability. Factors affecting the process are studied at the micro-scale using a model of a system of vessels of variable length and opening formed in the neighborhood of a stressed contact between two damage-affected grains. It appears that permeability is mildly affected by the contact area increase, and for most of the duration, by the precipitation of the mineral solute, until the inter-grain pores are almost completely clogged by the precipitate, when the permeability decreases very fast by orders of magnitude. Rigid chemo-plasticity model is employed to simulate the enhancement to dissolution induced by formation of new inter-phase interfaces at the walls of microcracks, represented by dilatant plastic strain. Such a process is widely believed to occur in oil/gas bearing sediments. Dissolution leads to chemo-plastic softening of the material. Couplings, feedbacks and feedforwards between mechanical, transport and geochemical processes caused by intergranular damage and dissolution are discussed.

Short TitleComputational Geomechanics, Comgeo Ii Proceedings of the 2nd International Symposium on Computational Geomechanics