Flow with simultaneous heterogeneous reactions in porous media

A theoretical model of the matrix acidization of sandstone by a hydrofluoric-hydrochloric acid mixture was developed. A capillary model of the pore structure was coupled with material balance equations describing the acid and solid species to yield a dynamic description of the acidization process. The model was solved first in linear coordinates so that it could be compared with the results of Berea sandstone core flood experiments which were performed previously. The acidization model was then applied in radial coordinates to generate design curves for a field-scale acidization treatment. The design curves developed in this study relate acid mixture injection rate and cumulative volume requirements to the desired distance of permeability improvement into the sandstone matrix as a function of temperature and rock composition.