A Transient Boundary Element Framework for Pressure Buildup, Injectivity Enhancement, and Reactive Permeability Evolution During CO₂ Storage in Heterogeneous Carbonate Reservoirs

<ns3:p>Background Reactive CO2 injection in heterogeneous carbonate reservoirs involves coupled pressure buildup, carbonate dissolution, porosity growth, and permeability evolution. Efficient prediction of these feedback is needed for pressure management and injectivity assessment in geological carbon storage. Methods A transient Boundary Element Method framework is developed for reactive CO2 storage in heterogeneous carbonate formations. The formulation combines time-dependent Green function solutions, analytical well-source representation, subdomain treatment of facies-scale heterogeneity, interface pressure and flux continuity, and incremental updating of reaction progress, porosity, and permeability. Results The proposed formulation reproduces nonreactive diffusion benchmarks, maintains interface continuity across heterogeneous subdomains, and captures the development of reactive near-well alteration zones. Reactive permeability enhancement reduces long-term pressure buildup and improves apparent injectivity, while initial heterogeneity controls early pressure redistribution and path-dependent hydraulic evolution. Conclusions The transient reactive BEM framework provides an efficient boundary-based tool for evaluating pressure-limited CO2 storage, injectivity enhancement, and reactive permeability evolution in heterogeneous carbonate reservoirs, while avoiding full volumetric remeshing during property updates.</ns3:p>