A hybrid multiscale framework coupling multilayer dynamic reconstruction and full-dimensional models for CO2 storage in deep saline aquifers

Abstract

Numerical modeling of CO2 injection in the deep saline aquifer is computationally expensive due to the large spatial and temporal scales. To address the computational challenge, reduced-dimensional models (e.g., vertical equilibrium (VE) and dynamic reconstruction (DR) models) based on vertical integration of the full-dimensional governing equations have been developed. VE models assume rapid segregation of the injected and the resident fluids due to strong buoyancy. Conversely, DR models employ a multiscale framework that relaxes the VE assumption and captures the vertical dynamics of CO2 and brine by solving the vertical two-phase flow dynamics as one-dimensional fine-scale problems. Although DR models relax the VE assumption while maintaining much of the computational efficiency of VE models, they are thus far limited to homogeneous and layered heterogeneous formations. We present a novel hybrid framework that couples a multilayer dynamic reconstruction model and a full-dimensional model. The new hybrid framework allows simulation of CO2 injection in geological formations with local heterogeneities. It employs a full-dimensional model in local heterogeneous regions (where the full-dimensional model should be used for accuracy), while applying the dynamic reconstruction model in the rest of the domain. Numerical simulations of CO2 injection in three heterogeneous reservoirs show that the hybrid model maintains the accuracy of the conventional full-dimensional models with significantly reduced computational cost. © 2021 Elsevier B.V.