Fundamental study of migration of supercritical carbon dioxide in porous media under conditions of saline aquifers

中国和英国政府都致力于减少温室气体排放，并将碳捕获和储存（CCS）视为实现这一目标的重要一步。两国进行了广泛合作，并鼓励采取新的举措。该项目是对EPSRC和中国国家自然科学基金委员会关于CCS的联合征集的回应，将解决征集中确定的优先主题“预测和监测储层响应”下的一个关键基础问题。在所设想的各种CO2封存方案中，地质封存已取得最好的发展，达到了可预见的大规模部署阶段。有三个潜在的地质储存地点，即盐水层、枯竭的油气藏和不可开采的煤层。其中第一种最受青睐，因为它提供了最大的潜在能力，而且可以广泛获得。在过去的10年里，全世界已经进行了10多个盐水层注入作业，还有更多的正在计划中。最近已经进行了大量的工作，研究了CCS的广泛主题，从现场剖面，环境影响，公众感知，经济可行性，到注入的技术性和储层特性。相比之下，有非常有限的研究解决的捕获机制和复杂的热力学条件下的多孔介质中的多相流动过程的基本原理。这是因为在高温高压下对多孔介质中的两相流动进行局部测量是非常困难的，并且还没有成熟有效的计算方案来解决多孔介质中复杂几何形状的大范围两相流动。拟议的研究将利用测量技术的最新发展，如磁共振成像（MRI）和数值方法，包括例如格子玻尔兹曼方法（LBM）。详细的调查将产生非常需要的定量描述的CO2迁移在多孔介质中的极端条件下遇到的含盐含水层的碳封存。从而提高我们对潜在物理过程的理解。流动行为的实验研究将在清华大学进行，使用一个在典型的深层盐水含水层条件下运行的、由专门建造的超临界CO2测试设施，并使用一个定制的MRI进行在线测量。研究了由等直径烧结玻璃珠制成的多孔介质和真实的岩石样品。将在利兹进行进一步的实验，研究这些岩石反应的地球化学行为，以及替代的储层岩性和地层水化学。计算研究将由Aberdeen领导，并在三个层次上进行：i）将根据第一性原理开发控制基本流动现象的基本方程的有限元解算器。ii）将开发一个有效的两相流LBM模型，用于模拟盐水中的CO2迁移。它将针对特定的流体性质和热力学条件进行优化。然后，上述两个求解器将用于研究物理问题，并生成从实验中无法获得的进一步详细信息。iii）还将继续使用商业软件进行CFD模拟。他们将提供补充数据，与我们的新方法进行比较。最后，整个多学科团队将利用新成果进行理论研究。所有的实验和计算结果将进一步处理，以产生与大规模模拟使用的相关性/关系，并将进行全面研究，以进一步了解多孔介质中的CO2/盐水两相流现象。

Both Chinese and UK governments are committed to reducing emissions of greenhouse gases and have recognised carbon capture and storage (CCS) as an essential step towards this goal. The two countries have collaborated extensively and encourage new initiatives. This proposal is a response to the joint Call for Proposals from EPSRC and NSFC of China on CCS and will address a key fundamental issue under the priority theme 'Predicting and monitoring reservoir response' identified in the Call.Among the various CO2 storage options conceived, geological storage has achieved the best development, reaching a stage at which large deployments are foreseeable. There are three potential locations for geological storage, i.e. saline aquifers, depleted hydrocarbon reservoirs and un-mineable coal seams. The first of these is mostly favoured because it offers the greatest potential capabilities and is widely available. Over the past 10 years there have been over 10 saline aquifers injection operations conducted worldwide, and many more are being planned.A vast amount of work has been conducted recently studying a wide range of topics of CCS, from site section, environmental impact, public perception, economic viability, to technicality of injections and reservoir behaviours. In contrast, there are very limited studies addressing the underlying fundamentals of the trapping mechanisms and the multi-phase flow processes in porous media under complex thermodynamic conditions. The reason is that local measurement of flow in porous media at high pressure and elevated temperature is extremely difficult, and also there are no well-developed and efficient computational schemes for resolving two-phase flow in a large domain of complex geometries of porous media. The proposed research will make use of the latest development in measurement technology such as Magnetic Resonance Imaging (MRI) and numerical methods including for example Lattice Boltzmann Method (LBM). Detailed investigation will generate the much needed quantitative description of CO2 migration in porous media at extreme conditions relevant to saline aquifers encountered in carbon sequestration. and hence improve our understanding of the underlying physical processes. Experimental investigations on flow behaviour will be conducted at Tsinghua using a purposely-built supercritical CO2 test facility operating at conditions typical of deep saline aquifers with online measurement using a custom-built MRI. Both porous media made of sintered glass beads of constant diameter and real rock samples will be studied. Further experiments will be conducted at Leeds studying the geochemistry behaviours of the reactions of these rocks, as well as alternative reservoir lithologies and formation water chemistries. The computational studies will be led by Aberdeen and conducted at three levels: i) a finite-element solver of the fundamental equations governing the basic flow phenomena will be developed based on first principles. ii) An efficient two-phase flow LBM model for application of modelling CO2 migration in brine will be developed. It will be optimised for the particular fluid properties and thermodynamic conditions. Both of the above solvers will then be used to study the physical problems and generate further detailed information which is not available from experiments. iii) Exercises using CFD simulations with commercial software will also be continued. They will produce complementary data to compare with our new methods. Finally theoretical studies making use of the new results will be carried out by the whole multidisciplinary team. All experimental and computational results will be further processed to produce correlations/relationships for use with large scale simulations and will be studied comprehensively to develop further fundamental understanding of the phenomena of CO2/brine two-phase flow in porous media.