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

近年来，通过稳定捕获和成矿作用将超临界二氧化碳封存在深层地下地层中受到了相当大的关注。 一旦就位，存在分离相超临界液体或溶解有二氧化碳的水通过覆盖层泄漏到较浅地层的可能性，具有严重环境后果的可能性。 需要对捕获和渗漏过程有全面的基本了解，才能估计地下二氧化碳储存能力，评估渗漏造成的生态和其他环境风险。 考虑到问题的复杂性，通过开发建模工具来设计现场应用程序，只有通过在多个尺度上分析问题，才有可能开发全面的基于过程的理解。这个项目将完成一系列创新的实验室砂缸实验，规模从小型（厘米）到中型（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，以完成适用于深层地层条件的实验，包括在环境实验室条件下的高压。现有的基于数值的模型，模拟多相流体流动的机制，包括截留，传质，密度驱动的混合，气泡迁移，将进行测试，以评估其捕获在实验室中观察到的基本过程的能力。这些模型的改进将使用本研究中产生的新知识。将开发和测试在实验室系统中表征的放大工艺的方法。这项研究与气候变化直接相关，因为它将导致旨在缓解大气二氧化碳增加的二氧化碳封存方法的改进。虽然对二氧化碳封存的某些方面进行了广泛的研究，但控制稳定储存和泄漏潜力的基本机制尚未得到足够的重视。通过将这些机制纳入模型，提高我们对这些机制的基本理解，将有助于改进选址和有效设计。最大限度地减少渗漏风险将有利于地下水质量、生态系统和环境。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和环境工程中其他多相流问题的研究人员共享。通过培训学生参与对减缓气候变化至关重要的进程的研究，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.