Numerical Investigation of Acid Wormholing During Acidization of Carbonate Formations

Matrix acidizing is a technique to stimulate wells for improving well inflow performance. In this treatment, acid solution is injected into the formation at pressure below the rock failure pressure to dissolve some of the minerals to increase permeability of carbonates near the wellbore. In this work, matrix acidizing has been simulated in the radial 3-D domain using continuum/average model. The reaction kinetics has been considered to be nonlinear at solid-liquid interface. The reservoir is considered as a heterogeneous media and the effects of acid molecular diffusion, acid convection by fluid bulk and acid reaction with rock in porous media are considered. Different dissolution patterns observed in the experiments are shown by numerical simulation results. To validate the model, one set of acidizing field data of well-5 Sarkhoon was used. Results are discussed in term of skin factor. In particular, the change in the dominant wormhole growth dynamic is investigated during wormhole propagation around the wellbore