CO2 storage potential in major oil and gas reservoirs in the northern South China Sea

Abstract

As 41 % of China’s CO2 emission comes from coastal provinces and cities, permanent sequestration of anthropogenic CO2 in offshore sediments is a priority to achieve China’s national goal of net zero by 2060. In this paper we evaluate the potential of CO2 sequestration in the major oil and gas reservoirs in the northern South China Sea (NSCS) bordering the southern provinces of Guangdong, Guangxi and Hainan. The calculation of the CO2 storage potential is based on voidage replacement for individual oil and gas fields. Our study shows that the overall CO2 storage potential in oil and gas reservoirs in the four major geological basins in NSCS has low, mid and high value of 1015.8, 1082.7 and 1151.5 Mt, respectively. About 84 % of the storage potential resides in gas reservoirs and 16 % in oil reservoirs. Though this storage volume is modest, it is adequate for an industry scale CO2 storage demonstration project where one to several Mtpa CO2 can be injected. Furthermore, we have identified two relatively mature gas fields, Dongfang 1-1 and Yacheng 13-1 in the Yinggehai basin as potential candidates for such a demonstration project where industrial CO2 from Hainan Island can be sequestered permanently. A feasibility study on this is warranted.