Effects of Pressure and Temperature on Well Cement Degradation by Supercritical CO2

The overall objective of this study was to
investigate the physical and chemical effects of supercritical CO2
attack on well cement at different temperature and pressure
condition. The dissimilarity of attack was compared in twoexposure
conditions i.e. CO2-saturated brine and wet
supercritical CO2. Type of cement used for this invent was neat
cement, Class G and was prepared according to API
recommended practice 10B-2 by using Constant Speed Mixer.
Curing of cement slurry and CO2 exposure test were done by
using Curing Chamber and Cement Autoclave. Measurement
and evolution of cement alteration against CO2 attack was
determined under various temperatures and pressure condition
at different exposure duration. Results from BackScattered
Electron of Scanning Electron Microscopy (BSE-SEM), Energydispersive
X-Ray Spectroscopy (EDX), X-Ray Diffraction (XRD)
and compressive strength tester was analysed and studied. At
high temperature, 1200C, cement will lose its strength faster than
lower temperature, 400C. Same goes to pressure, the strength will
lose faster in higher pressure, 140 bar as compared to lower
pressure, 105 bar. Faster reduction in strength was found in CO2-
saturated brine exposure compared to wet supercritical CO2.
Index Terms – Supercritical CO2, brine, alteration, compressive
strength, curing.