Chemical impacts of CO₂ flooding on well composite samples: Experimental assessment of well integrity for CO₂ sequestration

An abandoned well, completed without CO₂ resistant materials, is thought to be a potential pathway for CO₂ leakage to the surface. To examine the chemical impacts of a non-CO₂ resistant well, we prepared composite samples consisting of J-55 casing material, Portland cement and sandstone (referred to as simulated well sample ). Permeability of the simulated well sample decreased during a flow-through experiment using CO ₂-saturated brine. Precipitation of carbonate was found in both flow-through and batch experiments. The casing material was not degraded by CO₂ if bonding between the casing and cement was tight. The sandstone surrounding the cement therefore seemed to act as a buffer medium against CO₂ attack.