Optimum Conditions for Wormhole Formation in Carbonate Porous Media: Influence of Transport and Reaction

The effects of transport and reaction on the phenomenon of wormhole formation were investigated for a wide range of fluid systems including strong acids, weak acids, and chelating agents. These fluid systems are influenced by a variety of transport and reaction processes such as the transport of reactants to the surface, the reversible surface reactions, and the transport of products away from the surface. When these transport and reaction processes are taken into account, a common dependence of the dissolution phenomenon on the Damkohler number is observed. There exists an optimum Damkohler number at which a minimum number of pore volumes are required for channel breakthrough. This optimum Damkohler number occurs at approximately 0.29 for all the fluid/mineral systems investigated in this study. In addition, an optimum kinetic parameter exists at which wormhole formation is most efficient. This optimum kinetic parameter occurs at a value of about 130. Together, the Damkohler number and the kinetic parameter provide a complete description of the dissolution phenomenon.