An experimental study of the mineral carbonation potential of the Jizan Group basalts
Abdirizak Omar, Mouadh Addassi, Davide Berno, Abdulwahab Alqahtani, Niccolò Menegoni, Serguey Arkadakskiy, Jakub Fedorik, Zeyad Ahmed, Noushad Kunnummal, Sigurður R. Gíslason, Thomas Finkbeiner, Abdulkader M. Afifi, Hussein Hoteit, Éric H. Oelkers
Abstract
• Batch reactor carbonation experiments of subsurface well cuttings samples from Jizan carbon storage in basalt pilot well. • Reactive fluids composition indicates predominant plagioclase dissolution and rapid saturation with respect to calcite. • Post-reaction solids analysis confirms the precipitation of carbonate minerals on basalt grains recovered from batch reactors. • Experiment results present proof of carbonation of Jizan Group basalt and reiterate its potential as a carbon sink in southwest Saudi Arabia. The ability of Jizan basalts, a potential subsurface mineral carbon storage formation located in southwest Saudi Arabia, to carbonate water-dissolved CO 2 has been examined through a set of closed system batch fluid-rock experiments performed at 60 °C. Two Jizan basalt samples were collected from a CO 2 injection pilot test well at depths of 375 and 665 m below surface. The basalt samples are dominated by intermediate plagioclase (An ∼ 60 ) and a Ca-Mg pyroxene with minor chlorite and zeolite. The cleaned basalts were placed into individual sealed reactors along with either aqueous sodium carbonate or sodium bicarbonate solutions, and the experiments were conducted over a period of up to 250 days. The reactive fluid compositions in all experiments suggest that the dissolution of plagioclase dominates the basalt dissolution; calculations suggest that the fluids rapidly approach pyroxene equilibrium. The reactive fluids rapidly become saturated with respect to calcite. SEM imaging and EDS analysis confirm calcite growth on the basalt grains. In contrast, Al-bearing secondary minerals were not identified despite apparently being retained by the solid phases during the experiments. Notably, the dissolution rates of the Jizan basalts slowed considerably over time during the static batch experiments. This observation suggests that the relatively rapid dissolution of basalt by acidic CO 2 -rich fluids in a dynamic flow system creating a dissolution zone and precipitation zone, is essential for efficient in situ mineralization of CO 2 in basalts.