[S-CG54] New Insights of Fluid-Rock Interactions: From Surface to Deep Subduction Zone

[SCG54-10] Permeability enhancement in fractured peridotite with chelating agents

*Luis Salala^1,2, Noriaki Watanabe¹, Jiajie Wang¹, Atsushi Okamoto¹ (1.Graduate Schoool of Environmental Studies, Tohoku University, 2.Faculty of Engineering and Architecture, University of El Salvador)

Keywords:CO2 mineralization, Chelating agents, Peridotite, Permebility enhancement

Mantle peridotite, the most reactive rock with CO₂ in near-surface environments, is a promising candidate for CO₂ mineralization to mitigate atmospheric emissions. However, its low permeability and the volume-increasing nature of carbonation reactions present significant challenges for large-scale applications. Chelating agents have shown promise in enhancing rock permeability through selective mineral dissolution under geothermal conditions, but their application to fractured peridotite remains unexplored. This study investigates the potential of chelating agents for overcoming the low permeability in peridotite. Flooding experiments were conducted on fractured harzburgite samples at 200 °C under 15 MPa confining stress using an environmentally friendly chelating agent, N,N-bis(carboxymethyl)-L-glutamic acid (GLDA), at pH 4. Within two hours experiment conducted at 5 mL min^-1, olivine dissolution formed wormholes along fractures with thickness up to 250 μm, increasing permeability by up to 4-fold and releasing magnesium ions at concentrations up to 750 ppm. These findings highlight the potential of chelating agents to enhance the permeability of peridotite, enabling improved fluid flow, magnesium ion extraction, and subsequent carbonation reactions for implementing scalable carbon capture and storage solutions.