Feasibility study on associated CO2 geological storage in a saline aquifer for development of Dongfang 1 1 gas field

Key words:  Dongfang 1 1 gas field  CO₂  saline aquifer  geological storage  feasibility analysis

Abstract:

Dongfang 1 1 gas field, in the west of South China Sea, is associated with high concentration of CO₂. After screening and assessment, the LT13 1 structure located in Yinggehai Basin was chosen as the saline aquifer to sequestrate the CO₂ discharged from the terminal of gas field on Hainan Island. The reservoir simulation results show that CO₂ can be injected safely and steadily for 20 years at the rate of (10-20)×10⁴ t/a. According to field conditions, CO₂ is considered to be processed at first and compressed on the island, and then transported by long distance subsea pipeline at liquid state, finally injected into LT13 1 saline aquifer via a subsea wellhead. In the whole process, the node pressure is lower than 25 MPa. The recommended pipeline internal diameter and horizontal well tubing diameter are 0.10 m (or 0.13 m) and 0.115 m respectively. The economic analysis results show that CO₂ storage cost is 211-229 RMB/t, a little higher than that of other overseas demonstration projects because of the huge pipeline capital. If carbon tax is implemented in China, it will promote CO₂ geological storage projects to be put into practice.