Novel multi-scale 3D/4D characterization of pore networks in tight rocks: Enhanced understanding of clean gas extraction and safe carbon sequestration

 ‘Delivering affordable energy and clean growth’ is a crucial goal in the green paper “Building Our Industrial Strategy”. Clean gas extraction and safe carbon storage, are two essential aspects in achieving this goal. The precise reconstruction of the pore networks and understanding gas transport in tight rocks under subsurface conditions is a core problem in these areas. Linked issues around methane gas transport in tight rock reservoirs (i.e. shale, and tight-gas sands) and carbon dioxide storage in underground reservoirs and aquifers need to be understood urgently. The enhanced understanding will contribute in the transmission of traditional energy industry to a ‘low-carbon and resource-efficient energy system’ greatly. The aim of this fellowship is to build novel and advanced digital approaches fully to understand the complicated pore networks in tight rocks (shales and tight sands) across multiple scales. Strong heterogeneity and fine grain sizes of tight rocks makes the characterization of microstructure and pores network highly challenging. The high- temperature and high- pressure subsurface conditions even increase difficulty for the gas transport studies. The unclear pore network and flow behaviors adversely affect industrial decision making and sustainable development. This research will first characterize the microstructure in tight rocks over a wider size range than previously, from centimeter to nanometer (downscaling) utilizing advanced correlative 3D imaging techniques, and reconstruct the nano-scale pore system to centimeter-scale (upscaling) using a development of the multi-stage method previously proposed by the applicant. Gas transport under subsurface conditions through these complex pore networks will be observed using novel 4D imaging (3D plus time), leading to the testing of simultaneous methane gas extraction and carbon dioxide storage in tight rocks through the laboratory injection of carbon dioxide into methane (or analogue) bearing samples. The results extracted from images will be verified by laboratorial bulk properties measurement under high temperature and high pressure. The potential efficiency of instant gas recovery and safety of long-term carbon sequestration will be evaluated based on this research. Results of the fellowship will be delivered using unprecedented multi-scale 3D and 4D views. It will build 3D pore networks in tight rocks over the largest range of scales in the world, and present 4D gas storage and transport for the first time. The extensive experience of the applicant in geology and imaging, plus the world class 3D and 4D imaging facilities at the University of Manchester will ensure the project is low risk with high benefit. This fellowship will provide enhanced pore network models for gas extraction and carbon storage industry and test the technical feasibility of a clean energy solution that could reduce carbon emissions and produce methane gas that could be subsequently commercialized. Furthermore, it will advance the world-leading multiscale imaging and the digital rock research at the University of Manchester. Potentially, the successful experience can be lead to the combination structure of the gas extraction and carbon storage companies, and further lead this technique in the world.