Effects of Illitization on the Distribution of Salinity in the Alberta Basin, Canada: A Numerical Case Study

Ipsita Gupta
Department of Geological Sciences, University of South Carolina Columbia, South Carolina [email protected]

     Illitization is the process whereby expandable, hydrous smectite clays release interlayer water to form illite in shales and sandstones. It is well established that though the effect of illitization on generation of overpressures is generally small, it may be an important mechanism by which pore fluids in sedimentary basins are diluted.
     The purpose of this study is to investigate the effects of clay dehydration reactions on the distribution of modern day salinity in the Alberta Basin, Canada, in particular the effects of illitization on the dilution of pore fluids in the Colorado Shales which are dominantly composed of smectite/illite clay minerals. The Cardium Formation is a sandstone layer sandwiched between these thick shales and has salinity lower than that of surrounding shales. The main focus of this project is to investigate whether illitization may have contributed to the dilution of pore fluids in the Cardium Formation.
     Through a separate subroutine, Huang et al.’s kinetic expression for calculating the progress of illitization is being incorporated in the 2D transient-state, variable density, fluid and heat flow and solute transport, finite element FORTRAN code, COMPACT. The contribution of clay dehydration to fluid flow will be accounted for by a volume change in interlayer water as it is released into pore space.
     This research will provide a numerical case study for modeling diagenetic reactions and will help explore links between fluid flow and diagenesis in sedimentary basins.

AAPG Search and Discovery Article #90070 © 2007 AAPG Foundation Grants in Aid