Fundamental Study of Processes Associated with Stable Trapping and Potential Leakage of Sequestrated Carbon Dioxide in Deep Geologic Formations

近年来，超临界二氧化碳通过稳定的圈闭和成矿作用在深层地下地层中的封存受到了极大的关注。一旦就位，含有溶解二氧化碳的分离相超临界液体或水可能会通过盖层泄漏到较浅的地层，可能会造成严重的环境后果。需要对捕获和泄漏过程有全面的基本了解，以估计地下二氧化碳的储存能力，并评估泄漏造成的生态和其他环境风险。鉴于问题的复杂性，只有通过开发建模工具来设计实地应用程序，才有可能在多个尺度上分析问题，从而形成基于流程的全面理解。该项目将完成一系列创新的实验室沙槽实验，范围从小(厘米)到中等(米)，探索基本过程。拟议的研究将使用替代流体和创新的测试和测量方法，以完成适用于深部地层条件的实验，包括在实验室环境条件下的高压。现有的模拟多相流体流动机制的数值模型，包括捕获、传质、密度驱动混合和气泡迁移，将被测试，以评估它们捕捉实验室观察到的基本过程的能力。将利用本研究中产生的新知识对这些模型进行改进。将开发和测试在实验室系统中具有特征的放大过程的方法。这项研究与气候变化直接相关，因为它将导致二氧化碳封存方法的改进，旨在减缓大气中不断增加的二氧化碳。虽然二氧化碳封存的某些方面已经得到了广泛的研究，但控制稳定储存和泄漏潜力的基本机制还没有得到足够的重视。通过将这些机制纳入模型来改善我们对这些机制的基本理解，将有助于改进选址和高效设计。将渗漏风险降至最低将有利于地下水质量、生态系统和环境。这些独特的实验室数据集将与参与二氧化碳封存研究以及水文学和环境工程中其他多相流问题的研究人员共享。通过参与这项对缓解气候变化至关重要的过程的研究，对学生进行培训，将产生重大的教育影响。

Sequestration of supercritical carbon dioxide in deep subsurface formations through stable trapping and mineralization has received considerable attention in recent years. Once in place, potential exists for the separate phase supercritical liquid or water with dissolved carbon dioxide to leak through the capping layer to shallower formations with potential for serious environmental consequences. Comprehensive fundamental understanding of trapping and leakage processes is required to estimate subsurface carbon dioxide storage capacity and to assess ecological and other environmental risks from leakage. Given the complexity of the problem, developing a comprehensive process-based understanding, through developing modeling tools to design field applications, is only possible by analyzing the problem at multiple scales. This project will complete a set of innovative laboratory sand tank experiments at scales ranging from small (cms) to intermediate (meters) that explore the fundamental processes. The proposed research will use surrogate fluids and innovative testing and measuring methods to complete experiments applicable to deep formation conditions, including high pressures, under ambient laboratory conditions. Existing numerically based models that simulate the mechanisms of multiphase fluid flow, including entrapment, mass transfer, density driven mixing, and bubble migration, will be tested to evaluate their ability to capture the fundamental processes observed in the laboratory. Improvements to these models will be made using the new knowledge generated in this research. Methods to up-scale processes that are characterized in the laboratory systems will be developed and tested. This research is of direct relevance to climate change because it will lead to improvements in carbon dioxide sequestration approaches intended to mitigate increasing atmospheric carbon dioxide. Although some aspects of carbon dioxide sequestration have been extensively studied, the fundamental mechanisms that control stable storage and leakage potential have not received adequate attention. Improvement of our fundamental understanding of these mechanisms through incorporating them into models will facilitate improved site selection and efficient design. Minimizing the risk of leakage will be beneficial to groundwater quality, ecosystems, and the environment. The unique laboratory data sets will be shared with investigators involved in carbon dioxide sequestration research, as well as in other multiphase phase flow problems in hydrology and environmental engineering. Significant educational impacts will be achieved by training students through participation in this research on processes critical to climate change mitigation.