Failure behaviour wellbore cement in the presence of water and supercritical CO2

The presence of numerous abandoned wells in depleted oil and gas reservoirs might provide leakage paths thus compromising the integrity of long-term CO2 storage. However little data is available on the effect of CO2-saturated solutions on the failure behaviour of wellbore cement. Therefore, we performed triaxial compression experiments to study the effect of CO2 on the failure behaviour of Portland cement at reservoir conditions (T= 80 degrees C, Pc = 1.5 to 30 MPa). Weakening of the cement was observed due to injection of aqueous fluid, whereas addition of CO2 did not further reduce the mechanical strength of the material. (C) 2008 Elsevier Ltd. All rights reserved