A new theoretical model was recently developed to describe the chemical reactions of acid in porous carbonate media. Since the late 70’s, the three major unanswered questions of acid wormholing when pumped into carbonate formations have been: 1) How many dominant wormholes are created? 2) What is the spatial distribution of those dominant wormholes along the wellbore? 3) What is the leak-off profile from the dominant wormholes under radial flow conditions? This presentation presents a model that proposes answers to these three basic questions. Once answered, the reaction of acid in the matrix and the interaction of wormhole development become straightforward. The new model requires a major paradigm shift in the understanding of matrix carbonate acidizing and the variables that control wormhole growth. It was found that wormhole length is predominantly controlled by matrix porosity, permeability anisotropy, and volume of acid pumped and not by reactivity. It was found that wormhole diam