Congruent dissolution kinetics

Interaction of alkali with rock minerals in reservoir sand is complicated. Somerton and Radke (11) classified these interactions into surface exchange and hydrolysis, congruent and in congruent dissolution reactiaiSr and insoluble salt formation by reaction with hardness ions in the pore fluids and exchanged from sand surfaces. These interactions may also be classified into reversible adsorption or non-reversible chemical consurrp-tion, and kinetic controlled or instantaneous reactions. 

Mass action relationships for aluminosilicate-carbonate-water reactions will be the most important constraint in buffering pH if their reaction rates are fast enough to accommodate changing environmental conditions (kinetic constraint), and there are sufficient amounts of these minerals in the rock (mass balance constraint). To attempt to address the kinetic constraint first, we can consider how fast a mineral typical of low temperature alteration in both sediments and fractured hard rocks (albite) behaves. Albite (Na-plagioclase) has a congruent dissolution... 

A. Al Cheikh and M. Murat, Kinetics of non-congruent dissolution of E-glass fiber in saturated calcium hydroxide solution , Cem. Conor. Res. 18,1988, 943-950. 

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