The Journal of Physical Chemistry CChemi­cal and hydrodynamic mechanisms for long-term geological carbon storage” was the featured arti­cle in the July 17, 2014, issue of the Journal of Physical Chemistry C. The paper was written by Sandia researchers Susan Altman (in Sandia’s Geochemistry Dept.), Randall Cygan (in Sandia’s Geoscience Research & Applications Group), Craig Tenney (in Sandia’s Geoscience Research & Applications Dept.), Thomas Dewers and Hongkyu Yoon (both in Sandia’s Geomechanics Dept.), and Edward Matteo (in Sandia’s Nuclear Waste Disposal Research & Analysis Dept.) and 12 researchers from The University of Texas at Austin.

Relationship between the relative amount of carbon dioxide trapped by the different physical and chemical processes of trapping and time (modified after Benson et al.). Note that the timescale is speculative.

Relationship between the relative amount of carbon dioxide trapped by the different physical and chemical processes of trapping and time (modified after Benson et al.). Note that the timescale is speculative.

This team is part of Center for Frontiers of Subsurface Energy Security (CFSES), a joint Sandia/UT Energy Frontier Research Center (EFRC) funded by DOE-SC, Basic Energy Sciences (BES). Lead author Susan Altman, also serving as assistant director of CFSES, said the paper is a synthesis of CFSES research providing insights on trapping mechanisms for geological CO2 storage (GCS)/carbon sequestration.

The integration of pore-scale experiments, molecular dynamics simulations, and study of natural analogue sites has enabled understanding of the efficacy of capillary, solubility, and dissolution trapping of CO2 for GCS. Molecular-dynamics simulations provide insight on relative wetting of supercritical CO2 and brine hydrophilic and hydrophobic basal surfaces of kaolinite. Column experiments of successive supercritical CO2/brine flooding with high-resolution X-ray computed tomography imaging show a greater than 10% difference of residual trapping of CO2 in hydrophobic media compared to hydrophilic media that trapped only 2% of the CO2.