Potential of sub-seafloor CO_2 geological storage in northern South China Sea and its importance for CCS development in South China

摘要

The South China, especially Guangdong Province, as the most developed area of China emitted large CO_2 from energy consumption and industrial production, actively advocates low-carbon development strategies. As an effective option to reduce CO_2 emissions, CCS is potentially an effective option to reduce CO_2 emissions to low-carbon economy development of South China, especially to Guangdong province. The CO_2 storage potential in sedimentary basins onshore South China is limited as previous indicated. So the potential of sub-seafloor CO_2 storage in offshore basins would be important. According to the assessment in this paper, large sedimentary basins offshore in the northern SCS have huge CO_2 storage potential. Miocene deltaic, coastal plain, and neritic clastic rocks in these basins contain high-porosity and high-permeability aquifers and excellent seals. The estimated effective storage capacity, which is 2.6% of the theoretical capacity, is ～300 GtCO_2 in PRMB, ～57 GtCO_2 in BBGB, ～41Gt CO_2 in QDNB and ～160Gt CO_2 in YGHB. On the whole, the Tertiary sedimentary basins in northern SCS margin have large storage capacities of abut 567Gt CO_2, which provide a promising storage option for CCS implementation in South China. As the high costs is a major obstacles for sub-seafloor CO_2 storage, the reuse of infrastructures for oil and gas development, such as platforms, wells and pipelines, would be the first choice. Although the theoretical storage capacities of the offshore oil and gas fields in the northern SCS are small, they distributed as groups and clusters and associated with sufficient quantified CO_2 storage capacity in the saline aquifers. Further assessments are needed to define the residual life (= equipment life minus the field life) of the infrastructures, their practical and matched storage capacities, as well as a proper character and site screening particularly in regard to containment and risk of leakage. All these have been done well ahead of the real abandons of the oil/gas fields, so that the fields are in "CO_2 Storage Readiness (CSR)".