Simplified Numeric Simulation Approach for CO$_{2,g}$-Water Flow and Trapping at Near-Surface Conditions

TL;DR

This paper presents a simplified pseudo black-oil model for simulating CO₂-water flow and trapping under near-surface conditions, effectively capturing key physical phenomena with minimal computational complexity.

Contribution

The study introduces a straightforward simulation approach using simple PVT correlations and assumes instantaneous equilibrium, enabling efficient modeling of CO₂-water interactions at near-surface conditions.

Findings

Model accurately captures capillary, gravitational, and dissolution effects.

Error due to ignoring pressure-dependent solubility variations remains acceptable.

Approach validated against FluidFlower tank experiment data.

Abstract

To simulate CO$_{2,g}$-water flow in tank experiments, subject to viscous, gravitational and capillary forces as well as the dissolution of this gas (CO$_{2,aq}$), we constructed a simple pseudo black-oil model. Simple PVT correlations were used for gas density, viscosity, and solubility as based on experimental studies and equations of state from the literature. These solubility calculations assume instantaneous chemical equilibrium. The applicability of the approach is investigated by modeling the FluidFlower tank experiment (Nordbotten et al., 2022). The simulation captures the expected physical phenomena, including capillary filtration, gravitational segregation, and dissolution fingering. An error in the total mass, due to ignoring solubility variations with pressure remains acceptable as long as the pressure variation in the tank is small.