5:15 PM - 7:15 PM
[SCG54-P09] Change in physicochemical properties due to chemical reactions between Horoman peridotite/Mineoka serpentinite and CO2-bearing fluid
Keywords:CCS, Carbon mineralization, Peridotite, Serpentinite
Among the various methods of Carbon dioxide Capture and Storage (CCS), mineral trapping has attracted significant attention. Especially, peridotite has a high potential for CO2 storage due to significant abundance of divalent cations. However, there are no established methods for monitoring carbon mineralization. The purpose of this study is to establish effective parameters for monitoring carbon mineralization. So, we measured the temporal changes in the physical properties (porosity, electrical resistivity, seismic wave velocity) and chemical properties (pH, ion concentration) of cubic rocks and fluids resulting from the reaction between CO2-fluid and peridotite/serpentinite.
The samples in this research are peridotite, which had not undergone minimal aqueous alteration, collected along the Horoman River in Hokkaido. Also, We used serpentinite containing lizardite and chrysotile, collected from the Boso Peninsula in Chiba Prefecture. These samples were processed into cubes approximately 15mm in size and placed in small containers filled with distilled water. The reaction was then carried out in a pressure vessel filled with CO2. The CO2 partial pressure was set at 1 MPa, and the fluid pH was approximately 3.9. This acidic condition is expected to help dissolve minerals. Reacted samples were collected at 1, 2, 5, 10, 20, 50, and 100 days after the start of CO2 injection. The physicochemical properties (porosity, electrical resistivity, seismic wave velocity, pH, ion concentration) of the cubic rocks and fluid were measured. In addition, the microstructure of the reaction surface was observed using EPMA.
The measurements showed no significant changes in the physical properties of peridotite, while the physical properties of serpentinite were changed significantly. Porosity of serpentinite increased from 1% to approximately 2%, and electrical resistivity decreased slightly, while seismic wave velocity was more or less constant. The concentration of Mg ions in the fluid from serpentinite was significantly high, which probably reflects the dissolution of brucite.
These results indicate that the reaction of CO2 fluids with peridotite and serpentinite leads to changes in physicochemical properties of the rocks and fluids. These changes are caused by mineral dissolution. In addition, serpentinites tend to increase in porosity, but seismic wave velocity was changed little, indicating change in the pore geometry.
In the future, the spatial extent of the reaction by microstructural observation will be investigated and how it can be applied from laboratory to field scale phenomena will be tested.
The samples in this research are peridotite, which had not undergone minimal aqueous alteration, collected along the Horoman River in Hokkaido. Also, We used serpentinite containing lizardite and chrysotile, collected from the Boso Peninsula in Chiba Prefecture. These samples were processed into cubes approximately 15mm in size and placed in small containers filled with distilled water. The reaction was then carried out in a pressure vessel filled with CO2. The CO2 partial pressure was set at 1 MPa, and the fluid pH was approximately 3.9. This acidic condition is expected to help dissolve minerals. Reacted samples were collected at 1, 2, 5, 10, 20, 50, and 100 days after the start of CO2 injection. The physicochemical properties (porosity, electrical resistivity, seismic wave velocity, pH, ion concentration) of the cubic rocks and fluid were measured. In addition, the microstructure of the reaction surface was observed using EPMA.
The measurements showed no significant changes in the physical properties of peridotite, while the physical properties of serpentinite were changed significantly. Porosity of serpentinite increased from 1% to approximately 2%, and electrical resistivity decreased slightly, while seismic wave velocity was more or less constant. The concentration of Mg ions in the fluid from serpentinite was significantly high, which probably reflects the dissolution of brucite.
These results indicate that the reaction of CO2 fluids with peridotite and serpentinite leads to changes in physicochemical properties of the rocks and fluids. These changes are caused by mineral dissolution. In addition, serpentinites tend to increase in porosity, but seismic wave velocity was changed little, indicating change in the pore geometry.
In the future, the spatial extent of the reaction by microstructural observation will be investigated and how it can be applied from laboratory to field scale phenomena will be tested.