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

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.

The immediate beneficiaries of this project are researchers and academics who develop large-scale models and those who use those modelling tools for CO2 injection strategy and capacity studies. They will make use of the new data and improved understanding to test and improve the basic formulations used in the large-scale simulation models, and to find and correct any inappropriate assumption built into these models. Furthermore, new experimental techniques and numerical algorithms which emerge from the proposed research will benefit researchers working on broader applications such as groundwater utilisation and protection, fuel cells and chemical reactors. The next-level beneficiaries are major gas and coal fired power plants and other concentrated sources of CO2 and oil and gas production companies, who are interested in either capturing and storing CO2 they generate, or, using CO2 for enhanced oil recovery (EOR). They will benefit from the advance of CCS technology. Clearly, the ultimate beneficiaries are the general public and plants/animals on the planet, all will benefit from a benign climate. We will work towards maximising the impact through the following measures: Publications - This is the basic but probably most important step to maximise the impact of this fundamental research as the immediate beneficiaries are researchers and academics. Publication plan will be on the agenda of each project progress video conference (biannual). We will normally expect each PhD student to produce two journal publications and make two conference presentations. We expect four major publications from the first two themes, i.e., experiments on flow and computations, and two from the mineral-fluid interactions theme. We will also regularly attend workshops and seminars to communicate our results quickly and effectively to our peers and a wide public and have made explicit budget request for such activities. Specialised networks - These always produce a fast and efficient route for disseminating project results and receiving feedbacks. Currently the BY and RX are members/participants of several CCS related networks and international collaborative projects, e.g, CRIUS consortium, UKCCSC, and GeoCapacity, NZEC, COACH projects. It is expected that the present collaboration will also provide opportunity for other members of this team to be involved in activities organised by these networks and to expand their network in CCS. UK and China collaboration - Solid plans for the exchange of visits by investigators and students will be made at early stage of the project according to the outlines given in Justification of Resources. These visits together with the biannual progress meetings (video) will ensure that all the information/knowledge generated is promptly shared by all the team members. The team will explore further research collaboration opportunities in China and the UK. Collaboration and direct communication with the company - The industry project partner CO2DeepStore, an UK based company specifically focused on the commercialisation of geological storage of CO2 deep within the earth, has expressed keen interest in collaborating with the team in and outwith the proposed project. We will also actively seek further collaborations with industry. Further research - All Investigators have strong interest either in applying the results form this project to other areas or in applying the new data/knowledge in further studies in CCS applications. Training of personnel - An important impact of the proposed project is training a number of researchers both in the UK and in China, who will eventually make important impact to the society. In addition to the basic scientific training, they will be exposed to this large multi-disciplinary team. They will have opportunity to spend a period of time in partners' laboratory and frequently exchange ideas with them.