Contrary to current CCS (Carbon Capture and Storage) models, reaction experiments conducted at subsurface stress and temperature conditions reveal that feldspars, common, reactive grains in sandstone reservoirs, can undergo significant chemical and mechanical changes when exposed to CO₂ enriched water. These chemo-mechanical processes, including grain fracturing, dissolution, and clay precipitation, can modify fluid pathways and rock strength, potentially reducing reservoir productivity and increasing leakage risk.