CO₂ sequestration by magnesite mineralisation through interaction of Mg-brine and CO₂: integrated laboratory experiments and computerised geochemical modelling

ABSTRACT

Several Carbon Capture and Storage (CCS) techniques have been studied including injections of carbon dioxide (CO₂) into the mature and/or depleted hydrocarbon reservoirs and deep saline aquifers. This work aims to test storing CO₂ into the magnesium-rich evaporite strata and also into the stratigraphic intervals containing Mg-rich brines. The test simulates Mg-carbonation of the synthetic solution obtained from the Mg-evaporite mineral, bischofite – both experimentally in the laboratory condition and also through computerised geochemical simulation. The laboratory experiments, which resulted in the crystallisation of anhydrous magnesite, were analysed. The TOUGHREACT^TM, Geochemist’s Workbench^TM (GWB) and PHREEQC^TM software simulated the experiments as computerised geochemical model and tested the results for natural geological conditions. The geochemical simulations successfully demonstrate the immense CCS potential for the Mg-evaporite (as well as the sedimentary strata charged with Mg-evaporitic brine) at their subsurface geological occurrences at elevated pressure-temperature and high salinity.

KEYWORDS:

• Mineral carbonation
• magnesite
• geochemical modelling
• bischofite

Acknowledgments

We convey our special thanks to João Marcelo Ketzer, Rosane Angélica Ligabue, and Jeane Estela Lima Dullius for their valuable help. We are grateful to the facilities available at the Isotopic Geology Laboratory, to the Graduate Program in Geosciences of the Geosciences Institute of the Federal University of Rio Grande do Sul, Brazil, to the CEPAC/PUCRS, and to the IIT Bombay at Mumbai, India. We are thankful to the CNPq for the DT grant and to the IRCC, IIT Bombay, for the Seed Grant.

Disclosure statement

No potential conflict of interest was reported by the authors.