CO2 geological storage is a critical component of carbon capture, utilization and storage (CCUS) technology, and a key technical path towards achieving carbon neutrality. This study offers a comprehensive review of the theoretical and technical methods of onshore geological CO2 storage, and highlights that current CO2 terrestrial storage demonstration projects primarily focus on the traditional oil and gas reservoir collaborative flooding technology. Simultaneously, global CO2 geological storage projects have begun to accelerate the development of deep saline aquifers storage and large-scale clustering in the direction of tens of millions of tons. In comparison to land-based sites, marine carbon sequestration sites possess greater storage potential, and are gradually emerging as the primary battlefield for carbon sequestration in the future due to their distance from aquifers and associated low risk. Storage in deep saline aquifers at marine area is the primary research focus in carbon sequestration, while the storage of submarine basalt mineralization holds great potential. The storage of CO2 in the form of solid hydrate within appropriate seabed sediment environments or the formation of artificial CO2 hydrate cap layer is conducive to the safe and efficient development of natural gas hydrate resources, and has emerged as a new hot research topic. In the future, the focus of CO2 geological storage should be on the fine assessment and regional optimization of carbon storage potential, the implementation of demonstration projects of the entire marine geological carbon storage process encompassing capture, transportation, injection and geophysical monitoring, and the establishment of an intelligent, real-time, and professional database integrating geological, engineering and environmental aspects of carbon storage. This study holds significant relevance in accurately identifying the future technical research direction of CO2 geological carbon sequestration, fostering technological advancements and innovations in carbon sequestration, and propelling the leapfrog development of CO2 carbon sequestration in the submarine areas.
Sedimentary and volcanic tablelands host the world's largest landslide areas, sometimes spanning hundreds of kilometers along escarpments. This study, employing new remote sensing-based mapping and drawing on an expanding body of literature on paleogeographic evolution, revises the extent, controls, and chronology of some of Earth's largest coalescent landslides in the volcanic tableland of extra-Andean Patagonia. Mostly ancient rotational slides and rock spreads, accompanied by earthflows and occasional rock avalanches, cover approximately 30,000 km2, roughly a fifth of the Patagonian escarpments, with the largest landslide areas exceeding 1000 km2. The immense size of the failed tableland in Patagonia is inherited from stratigraphy and geological history: weak marine and continental Cretaceous-Miocene sedimentary and volcaniclastic rocks, capped by plateau basalts, create a highly unstable environment, outcropping along thousands of kilometers of escarpments. Most landslide areas occupy the steepest, most dissected parts of Patagonian tableland, occurring independently of recent climatic conditions. Some of the largest complexes are found in both the most humid and arid regions. Cross-cutting relationships between landslides and dated glacial, lacustrine, marine deposits, and lava flows reveal that some landslides have persisted for several million years, marking them as some of Earth's oldest landslide terrains with distinctive geomorphological footprints. Future research on failed Patagonian tableland should include direct radiometric dating, InSAR technology monitoring, and numerical stability modeling of landslides. This comprehensive approach will deepen our understanding of their origins and determine whether these giant landslide fringes predominantly represent fossil features or could be reactivated under contemporary environmental conditions.
Earthquake-induced liquefaction is a prominent and impactful natural hazard responsible for substantial economic losses worldwide. Hence, engineers and researchers are currently interested in developing methods and techniques to mitigate this destructive phenomenon. Reducing the degree of saturation is a reliable method to improve the liquefaction resistance of sandy soils since it directly influences the pore pressure build-up during seismic action. This paper reviews the mechanisms and assessment of earthquake-induced liquefaction in sandy soils with various degrees of saturation, a crucial parameter for reducing the phenomenon triggering. In addition, it presents novel approaches that delve into interpreting cyclic behaviour with diverse degrees of saturation using stress-based and energy-based approaches. The experimental results compiled and discussed show that, effectively, reducing the degree of saturation holds promise as a viable strategy for enhancing soil liquefaction resistance and mitigating associated risks. Moreover, the interpretation of cyclic behaviour addressed in this paper offers valuable insights into the reliability of interpreting methods to quantify the liquefaction resistance under several degrees of saturation (that may be achieved by desaturation or induced partial saturation techniques), contributing to strategies for resilience against earthquake-induced damages.
Fracture-filling hydrate constitutes a pivotal component within the global hydrate reserves and serve as a significant focal point for hydrate exploration and development. However, the understanding of the formation mechanisms and geophysical properties of fracture-filling hydrate in sediments remains unclear. This review seeks to bridge this knowledge gap by comprehensively examining the formation mechanisms of fracture-filling hydrate from both micro-sedimentary and geological reservoir perspectives. It delves into various aspects of field tests, including seismic and logging, as well as laboratory tests covering acoustic properties, permeability, thermal properties, electrical resistivity, and mechanical properties. It aims to shed light on the challenges associated with the characteristics of fracture-filling hydrate reservoirs and their geophysical properties while proposing potential solutions, and emphasizes the urgency of identifying the formation patterns of fracture-filling hydrate and estimating resource volumes. Furthermore, the review emphasizes the importance of collaborative geophysical characterization testing for fracture-filling hydrate as a crucial step in addressing this challenge. It advocates for fostering international cooperation for global data integration and sharing as a viable solution to advance our understanding and management of these valuable resources.