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 CO2-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.