Modeling of Wormhole Formation during Matrix Stimulation of Carbonates

An averaged/continuum model is used to model wormhole formation during matrix stimulation of carbonate. The model considers pore level physics by coupling the local pore scale phenomena to the macroscopic variables through the structure-property relationships and the dependence of fluid-solid mass transfer coefficient and fluid phase dispersion coefficient on the evolving pore scale variables. To explain wormhole formation, numerous models, ranging from porescale models (network models) to single wormhole (tube) models have been developed in the literature2, 3, 5. The model used here has three fundamental aspects. First, the dissolution process creates a Darcy velocity with non-zerodivergence. Second, two concentration variables have been used to consider the local gradients at the pore level caused by the coupling between the flow, species diffusion and chemical reaction. Third, this model considers both the diffusive and convective contributions to the local mass transfer coefficient between the fluid and solid. In this work, the model is numerically solved by finite difference method. The effect of acid injection through the core at different times and locations on parameters including pressure, concentration in solid and fluid phases is investigated. The results show that the used model captures the features of acidizing qualitatively.

کلیدواژه ها:

Matrix acidizing ، Carbonate rock ، Wormhole ، Porous media ، Dissolution