INVESTIGATION OF ADMIXTURES EFFECT ON DEGRADATION OF CEMENT PASTE IN SAGD AND CCS WELLS

In recent years, Steam Assisted Gravity Drainage (SAGD) and Carbon dioxide Capture and Storage (CCS) projects are being developed in oil and gas fields. SAGD is a heavy oil recovery technology to reduce heavy oil viscosity and extract it from underground. CCS is a technology to inject CO2, emitted from plants, into a couple of 1000m deep ground through well. The deterioration of well in SAGD and CCS projects may cause leakage of deleterious gas. In this study, mechanical and chemical degradation of hardened cement paste made of Oil Well Cement (OWC) and Geothermal Well Cement (GWC) containing silica flour in the wells was studied experimentally. In order to imitate the underground condition of SAGD, the cement paste was exposed to the drying and moist sealed condition at 200°C. In addition, the cement paste was exposed to supercritical CO2 to reproduce the condition to inject CO2 gas in CCS well. The compressive strength tests after exposure to 200°C and thermal analysis to study carbonation after exposure to supercritical CO2 suggested that the replacement of silica flour to cement is effective to be applied to both SAGD and CCS injection wells