Pore-scale modeling of multiphase reactive transport in porous media during geological carbon storage in saline aquifers: Mechanisms, progress, and challenges

Abstract

Geological carbon storage (GCS) represents a promising strategy for atmospheric CO₂ reduction and climate change mitigation, with deep saline aquifers standing out as suitable storage sites due to their wide distribution and large storage capacity. The intricate CO₂-brine-rock interactions during GCS in saline aquifers encompass coupled multiphase flow dynamics, multi-component reactive transport, aqueous-phase homogeneous reactions, and fluid/mineral heterogeneous reactions processes. These processes underpin four primary trapping mechanisms: structural trapping, capillary trapping, dissolution trapping, and mineral trapping. Pore-scale modeling bridges the microscopic and macroscopic scales by providing detailed three-dimensional distributions of physical fields within pore spaces while capturing the evolution of porous media due to geochemical reactions. This comprehensive review not only examines the mechanisms and physicochemical processes underlying CO₂ trapping, but also discusses recent advancements in GCS research within saline aquifers from a pore-scale modeling perspective. Furthermore, challenges and future research directions are discussed. This review provides fundamental insights into multiphase reactive transport at pore scale, supporting the development of predictive models that can enhance the safety and efficiency of long-term CO₂ storage in deep saline aquifers.