Effect of biofilm formation on multiphase flow and wetting properties during cyclic injection of hydrogen in rocks

为了应对全球变暖和气候变化日益加剧的担忧，当今社会正寻求转向环境友好型和可再生能源。在各种能源选择中，氢气(H2)正受到极大的关注，并可能成为英国经济的一项主要资产，预计到2050年，其GVA将达到180亿GB/年。然而，大规模储存氢气以应对未来需求构成了重大挑战。地下储氢可以提供一种有效的解决方案；然而，在野外实施这项技术之前，需要进行大量的基础研究。氢气储存带来的一些挑战是：(I)对多孔岩石中循环注入氢气的孔隙尺度行为的基本认识有限。这方面目前正在由我们的博士生Zaid Jangda在IGE进行研究；以及(Ii)由于H2与驻留卤水中存在的微生物(H2是地下微生物活动的有效能源)长期相互作用而形成的生物膜，这将在本项目中进行研究。生物膜的形成可能会阻塞可用的孔隙空间，这可能会对孔隙度和渗透率产生不利影响，从而对进一步循环的存储能力产生不利影响。此外，生物膜的形成是否会改变H2-卤水-岩石系统中岩石样品的润湿性还是个未知数。如果发生润湿性改变，会对岩石中H2的流动特性产生重大影响。该项目将通过使用批处理和流动实验进行实验性和3D X射线成像研究来解决这些挑战。这一结果将使我们能够仔细检查在岩石中注氢期间影响生物膜形成的各种参数。此外，它还将使我们能够表征由于生物膜引起的孔隙空间变化和润湿性变化以及它们对流动特性的影响。结果将使我们能够开发预测氢气储存的可靠模型(建模不在本项目的范围内)。除了拟议的工作外，长期目标是开发实验策略，以防止可能对氢气存储产生不利影响的生物膜。

In response to increasing concerns of global warming and climate change, today's society is seeking to shift towards environmentally friendly and renewable energy sources. Among various energy options, hydrogen (H2) is receiving significant attention, and is likely to form a major asset of the UK's economy with an expected GVA of £18 billion/year by 2050. However, large-scale storage of H2 to account for future demand poses major challenges. Underground storage of H2 can provide an effective solution; however, substantial fundamental research is needed before implementing this technique at the field scale. Some of the challenges that H2 storage presents are: (i) the limited fundamental understanding of pore-scale behaviour of cyclic injection of H2 in porous rocks. This aspect is currently being investigated by our PhD student Zaid Jangda at IGE; and (ii) the formation of biofilms due to long-term interaction of H2 with the microbes present in the resident brine (H2 is an effective energy source for subsurface microbial activities), which will be investigated in this project. The formation of biofilms can block the available pore space, which can adversely affect porosity and permeability, and consequently the storage capacity for further cycles. Moreover, it is unknown if the formation of biofilms can alter the wettability of rock samples in a H2-brine-rock system. If wettability alteration occurs, it can significantly affect the flow properties of H2 in rocks. This project will address these challenges by conducting an experimental and 3D X-ray imaging study using batch and flow through experiments. The results will allow us to scrutinise various parameters that can impact the formation of biofilms during H2 injection in rocks. Moreover, it will enable us to characterise the pore space variations and wettability alteration due to biofilms and their impact on flow properties. The results will allow us to develop robust models for the prediction of H2 storage (modelling is not in the scope of this project). The long-term goal, beyond the proposed work, is to develop experimental strategies to prevent biofilms that can adversely affect H2 storage.