InterPore2026

An iterative, two-way coupling of regional and site models for multi-scale CO$_2$ injection simulations

22 May 2026, 15:30

1h 30m

Poster Presentation (MS07) Mathematical and numerical methods for multi-scale multi-physics, nonlinear coupled processes Poster

Speaker

Eda Onal (University of Bergen)

Description

Carbon capture and storage involves injecting CO$_2$ underground while keeping the reservoir pressure within a safe limit. In large, connected aquifers pressure changes can move far from an injection well, so separate injection sites can influence each other through regional pressure buildup. At the same time, each site is controlled by local details such as near-well pressure gradients and detailed geological features. Operators therefore use independent site models for local details and a separate coarse model for regional pressure communication. This leads the main question of this work: how can the regional and site models be coupled to capture pressure interference?

In this work, we investigate a coupling strategy between a coarse regional model and a locally refined site model. Focusing on capturing pressure dynamics, we consider single-phase incompressible Darcy flow with rate-controlled injection wells. The computational domain is split into a coarse regional subdomain and a locally refined site subdomain. The coupling is performed by an two-way iterative scheme. Each iteration proceeds as follows: (i) solve the regional problem on the coarse grid, (ii) prolong the coarse correction to the site grid and form a predicted site state, (iii) map regional interface (face) pressures to prescribed site boundary pressures, (iv) solve the site problem on the fine grid, and (v) restrict the fine correction to the overlapping coarse cells to update the regional pressure.

We evaluate the method with numerical experiments where a fine site model at a fixed resolution is embedded in a coarse regional model. We run experiments in both homogeneous and heterogeneous 2D domains and vary the regional grid size to study how coarse resolution affects the coupled pressure response. We observe that iterating improves agreement with a full monolithic fine-grid reference, with most improvement occurring within the first iterations. As the iterations improves the solution, the remaining mismatch is mainly dominated by the regional grid resolution.