Influence of deformation on the fluid transport properties of salt rocks

Abstract

While the fluid transport properties of rocks are well understood under hydrostatic conditions, little is known regarding these properties in rocks undergoing crystal plastic deformation. However, such data are needed as input in the field of radioactive waste disposal in salt formations. They are also needed to understand deformation, shear zone evolution and associated fluid movement, metamorphism and mineralization in the deep crust and even upper mantle. The present study is concerned with the development of a fundamental understanding of the influence of crystal plastic deformation on dilatancy and permeability evolution in salt rocks and salt/anhydrite rocks. It is experimentally based and seeks to explain the influence of deformation on permeability in the framework of "percolation theory", currently finding wide application in solid state physics. The results relate directly to the behaviour of salt rock in disposal systems and, viewing salt as an analogue material, provide insight into the effects of plastic deformation on the fluid transport properties of crystalline rocks in general.