Extended Søreide-Whitson equation of state for CO2-brine equilibrium using an ion-specific parameterisation
Year: 2025
Type: article
Abstract: Carbon capture and storage (CCS) initiatives rely on understanding the behaviour of CO 2 in saline aquifers, where solubility trapping is a key mechanism. Experimental data, while critical for model validation, are resource-intensive to obtain. Thermodynamic models, such as the Søreide-Whitson framework, offer an efficient alternative for evaluating CO 2 solubility under reservoir conditions. In this work a generalised Søreide-Whitson model is presented to calculate the solubility of CO 2 in pure water and brine solutions on an ion-specific basis across a wide range of temperatures (273–473 K), pressures (up to 50 MPa), and salinities (up to 6 mol⋅kg -1 ). The updated model includes expressions for , , , , , , and . The modified model introduces generalised expressions for the α-function and phase-dependent binary interaction parameter based on individual concentrations of ions rather than salts. This approach significantly improves the accuracy of CO 2 solubility predictions in brines containing multiple salts, as demonstrated through comparisons with experimental data. The generalised model maintains its robustness for mixed-salt brines and is readily implementable in simulation tools, expanding its applicability for CCS evaluations.
Source: Gas Science and Engineering
Authors: Sonja A.M. Smith, Erling H. Stenby, Wei Yan
Institution: Technical University of Denmark
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
SDG: Climate action
Open Access status: hybrid
Estimated APC paid: $3,550
Funder: Innovationsfonden
Award: G3926580652
OpenAlex ID: W4411111640