Comprehensive Review of Caprock-Sealing Mechanisms for Geologic Carbon Sequestration

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• 作者：Juan Song ; Dongxiao Zhang
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：January 2, 2013
• 年：2013
• 卷：47
• 期：1
• 页码：9-22
• 全文大小：439K
• 年卷期：v.47,no.1(January 2, 2013)
• ISSN：1520-5851

文摘

CO₂ capture and geologic sequestration is one of the most promising options for reducing atmospheric emissions of CO₂. Its viability and long-term safety, which depends on the caprock鈥檚 sealing capacity and integrity, is crucial for implementing CO₂ geologic storage on a commercial scale. In terms of risk, CO₂ leakage mechanisms are classified as follows: diffusive loss of dissolved gas through the caprock, leakage through the pore spaces after breakthrough pressure has been exceeded, leakage through faults or fractures, and well leakage. An overview is presented in which the problems relating to CO₂ leakage are defined, dominant factors are considered, and the main results are given for these mechanisms, with the exception of well leakage. The overview includes the properties of the CO₂鈥搘ater/brine system, and the hydromechanics, geophysics, and geochemistry of the caprock-fluid system. In regard to leakage processes, leakage through faults or fracture networks can be rapid and catastrophic, whereas diffusive loss is usually low. The review identifies major research gaps and areas in need of additional study in regard to the mechanisms for geologic carbon sequestration and the effects of complicated processes on sealing capacity of caprock under reservoir conditions.