3-D simulation and analysis of reactive dissolution and wormhole formation in carbonate rocks

We present 3-D simulations of wormhole formation in carbonate rocks using a two-scale continuum model. We employ the multigrid technique to obtain accurate solution of the model and analyze wormhole patterns in various acidization regimes. We also present a sensitivity analysis of the dissolution process with respect to acid injection rate, dissolution rate constant and rock properties such as initial average permeability, heterogeneity and permeability–porosity relationships. Finally, we determine the wormhole properties such as tip diameter and fractal dimension and compare the simulation results with available experimental data. The effect of heterogeneity magnitude on wormhole pattern (a) Δε0=0.01 and (b) Δε0=0.1. A low heterogeneity (Δε0=0.01) leads to a smooth wormhole. As the heterogeneity magnitude is increased (Δε0=0.10) the wormhole becomes branched and fractal in nature. [Display omitted] ▸ Scaling analysis is used to estimate wormhole tip diameter. ▸ The dependence of the optimum injection rate on rock properties is estimated. ▸ The structure of the wormhole is computed under various conditions. ▸ Sensitivity of wormhole properties with respect to rock properties is presented.