Experiments and Modeling of Acid Dissolution Fingering

Acidizing and wormholing in carbonate reservoirs is studied through the analysis of the linear acidizing problem theoretically and experimentally. Experimentally, linear acidizing tests were performed in Mons chalk, a high porosity analogue of North Sea reservoir chalk. In the experiments the critical injection velocity for wormhole formation at minimum acid injection was obtained. Theoretically acidizing was analyzed by formulating the problem as reactive moving boundary Stefan type problem. Wormholing was analyzed through a linear stability analysis from the equilibrium state of uniform dissolution. The results of the stability analysis determined the critical injection velocity for wormholing and size effect with respect to the specimen diameter.