One of the major technological issues for CO 2 injection is the long-term behavior of the cement-based materials used to ensure the overall sealing performance of the storage wells. When water is present, the CO 2 injected can react chemically with the cement (i.e. carbonation). The objectives of our experimental program are to assess the kinetics and phenomenology of the changes that occur in class-G Portland cements exposed to CO 2 -enriched aqueous fluids at 8 MPa and two different

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... es (90°C and 140°C). The experimental program presented in this paper consists of two carbonation tests (static tests) and a coupled chemo-mechanical test (dynamic test) which were performed on similar class-G cement and similar CO 2 -rich water. The main preliminary results show a carbonation front progressing from the fluid-sample interface towards the sample centre. The front moves faster at 140°C than 90°C because of the different carbonation process involved at this higher temperature. The results of a coupled chemo-mechanical test with injection of CO 2 -saturated water show that the CO 2 flow rate in the cement rapidly decreases, finally resulting in carbonation clogging of the cement sample. They seem consistent with reported field observations.