CO2 leakage in shallow aquifers: A benchmark modeling study of CO2 gas evolution in heterogeneous porous media. (August 2015)

• Record Type: Journal Article
• Authors: Porter, Mark L.; Plampin, Michelle R.; Pawar, Rajesh; Illangasekare, Tissa
• Is Part Of: International journal of greenhouse gas control. Volume 39(2015:Aug.)
• Page Start: 51
• Page End: 61
• Publication Date: 2015-08
• Subjects: Carbon sequestration -- CO2 leakage -- Exsolution -- Multiphase flow -- FEHM; Greenhouse gases -- Environmental aspects -- Periodicals; Air -- Purification -- Technological innovations -- Periodicals; Gaz à effet de serre -- Périodiques; Gaz à effet de serre -- Réduction -- Périodiques; Air -- Purification -- Technological innovations; Greenhouse gases -- Environmental aspects; Periodicals; 363.73874605
• DOI: 10.1016/j.ijggc.2015.04.017
• Languages: English
• ISSNs: 1750-5836

Abstract

Abstract : Highlights: Simulated intermediate scale column experiments of CO2 gas exsolution in heterogeneous porous media. Developed and validated an expression to predict the critical pressure at which free phase CO2 gas forms. Our simulations capture experimental observations, including CO2 gas accumulation zones in heterogeneous sands. Abstract: The physicochemical processes associated with CO2 leakage into shallow aquifer systems are complex and span multiple spatial and time scales. Continuum-scale numerical models that faithfully represent the underlying pore-scale physics are required to predict the long-term behavior and aid in risk analysis regarding regulatory and management decisions. This study focuses on benchmarking the numerical simulator, FEHM, with intermediate-scale column experiments of CO2 gas evolution in homogeneous and heterogeneous sand configurations. Inverse modeling was conducted to calibrate model parameters and determine model sensitivity to the observed steady-state saturation profiles. It is shown that FEHM is a powerful tool that is capable of capturing the experimentally observed outflow rates and saturation profiles. Moreover, FEHM captures the transition from single- to multi-phase flow and CO2 gas accumulation at interfaces separating sands. We also derive a simple expression, based on Darcy's law, for the pressure at which CO2 free phase gas is observed and show that it reliably predicts the location at which single-phase flow transitions to multi-phase flow.