自工業革命以來，大氣中二氧化碳濃度不斷增加，對生態環境及全球氣候造成影響。碳捕獲與封存為其中一個有效減緩溫室效應的方法，藉由源頭捕捉二氧化碳，再運輸至適合的地點儲存以降低大氣中的濃度，其中地層封存是將二氧化碳儲存在地下枯竭油氣層、深層鹽水層中，因特定溫度及壓力環境，使二氧化碳形成超臨界態(Supercritical CO2)，因同時具液態之高密度及氣態的高流動性，而適合長時間儲存在岩石圈之密閉空間及孔隙內，但在儲存及運輸過程中二氧化碳接觸套管水泥後易使之碳化(Carbonation)。
經由前人研究發現，油井水泥中添加適當比例之碳化矽及二氧化矽均能有效維持試體性質、減緩碳化造成的影響，因此本實驗將油井水泥加入3wt.%碳化矽及5wt.%二氧化矽，置於三種溫度及壓力(45°C、13.2MPa; 52°C、16.2MPa; 60°C、18.8MPa)之超臨界二氧化碳環境中反應28天。結果顯示，添加二氧化矽之水泥更能填補孔隙，形成緻密之試體抵抗碳酸侵蝕，其滲透係數、超聲波試驗及楊氏模數皆較添加碳化矽試體佳，另發現試體過渡區中鈣矽比較低之試體因能形成細小矽晶體填補孔隙、支撐試體受壓，有較佳之單軸壓縮強度。

Geological storage is the method to store carbon dioxide underground in places like depleted gas reservoirs and deep saline aquifers. Under the specific temperature and pressure environment, the carbon dioxide is formed into a supercritical state (Supercritical CO2, sCO2). sCO2 has the characteristics of high density in the liquid state and high fluidity in the gaseous state, it is suitable for long-term storage in the confined space and pores of the lithosphere. However, carbon dioxide may easily carbonize the casing cement after they contact during storage and transportation.
Through previous separate studies, it was found that adding 3wt.% silicon carbide(SiC) and 5wt.% silicon dioxide(SiO2) to oil well cement can maintain the best properties and most effectively slow down the impact of carbonization. Therefore, 3wt.% SiC and 5wt.% SiO2 was proposed in this study as an additive to oil well cement. Three sCO2 environments were selected, their temperature and pressure are 45°C, 13.2MPa; 52°C, 16.2MPa; 60°C, 18.8MPa. These proposed specimens were exposed in these sCO2 environments for 28 days. The viscosity and specific gravity of the slurry samples were measured. The permeability, ultrasonic velocities, uniaxial strength, the depth of carbonation of these specimens were measured at 0, 7, 14, 28 days of exposure. After 28 days, SEM and EDS were performed for each specimen. The results show that the cement with 5wt.% SiO2 can fill more pores and form a denser specimen to resist carbonic acid corrosion than the one with 3wt.% SiC. Furthermore, this study finds that the specimens with a lower Ca/Si ratio in the transition zone has a higher value in uniaxial compressive strength.

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