Chemical Reactions of Portland Cement with Aqueous CO2 and Their Impacts on Cement's Mechanical Properties under Geologic CO2 Sequestration Conditions
Chemical Reactions of Portland Cement with Aqueous CO2 and Their Impacts on Cement's Mechanical Properties under Geologic CO2 Sequestration Conditions
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DOI：
10.1021/es5063488
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发表时间：
2015-05-19
影响因子：
11.4
通讯作者：
Jun, Young-Shin
中科院分区：
文献类型：
--
作者：
Li, Qingyun;Lim, Yun Mook;Jun, Young-Shin
为了提供有关地质CO2封存（GCS）应用中井筒水泥完整性的信息，对水泥进行了化学和机械改变。分析反应10天的水泥浆样品。在昏迷状态下反应在95 ℃下进行，并且使100巴的N-2（对照条件）或CO2与反应盐水溶液接触，其中通过NaCl调节离子强度为0.5M。化学分析表明，3.0cm × 1.1cm × 0.3cm的试样受到CO_2水溶液的侵蚀，形成了层状结构，总侵蚀深度达1220 μ m。微观力学性能分析表明，碳化层的硬度和压痕模量比未碳化层大2-3倍，而硅酸盐溶解区的硬度和压痕模量下降了近50%。散装水泥样品的强度和弹性模量分别降低了93%和84%。微尺度区域的性质、层结构、微裂纹和外层的溶胀结合起来影响整体机械性质。这些发现从化学和力学的角度提高了对井筒完整性的理解，并可用于提高CO2储存的安全性和效率。
To provide information on wellbore cement integrity in the application of geologic CO2 sequestration (GCS), chemical and mechanical alterations were. analyzed for cement paste samples reacted for 10 days. under GCS conditions. The reactions were at 95 degrees C and had 100 bar of either N-2 (control condition) or CO2 contacting the reaction brine solution with an ionic strength of 0.5 M adjusted by NaCl. Chemical analyses showed that the 3.0 cm X 1.1 cm x 0.3 cm samples Were significantly attacked by aqueous CO2 and developed layer structures with a total attacked depth Of 1220 mu m. Microscale mechanical property analyses showed that the hardness and indentation modulus of the carbonated layer were 2-3 tithes greater than for the intact cement, but those in the portlandite-dissolved region decreased by similar to 50%. The strength and elastic modulus of the bulk cement samples were reduced by 93% and 84%, respectively. The properties of the microscale regions, layer structure, microcracks, and swelling of the outer layers combined to affect the overall mechanical properties. These findings improve understanding of wellbore integrity from both chemical and mechanical viewpoints and can be utilized to improve the safety and efficiency of CO2 storage.