Abstract: Marine carbon dioxide (CO₂) storage is an important means to cope with greenhouse gas emissions in China’s coastal areas, and is an indispensable key technology to achieve the goal of “emission peak and carbon neutrality”. The coastal areas of China are industrially developed and rich in carbon sources. Owing to the good physical properties and reservoirs and trap characteristics, offshore basins have huge storage potential. At present, the first marine demonstration project of China has been officially launched in the Pearl River Estuary Basin in the South China Sea. As an important part of CCUS technology, CO₂ monitoring runs through the whole life cycle of CO₂ geological storage and is a necessary method to ensure the safety and rationality of storage works. However, China’s CO₂ marine storage technology is in its infancy, and the task of marine storage monitoring is quite challenging. For this reason, this paper reviews the relevant representative research and demonstration project cases of international CO₂ marine storages, summarizes the monitoring indicators, technologies and schemes, and puts forward the screening and optimization methods of monitoring CO₂ marine storage and suggestions for monitoring technology. The outcome of this study provides a reference for the development of CO₂ marine storage demonstration projects in China.

Key words: carbon dioxide capture, utilization and storage (CCUS), offshore CO2 storage, marine environmental risks, safety
monitoring, monitoring technologies