A review of CO₂ storage potential of depleted gas reservoirs in Northern South China Sea: taking YC13-1 and DF1-1 gas fields as example

Carbon Capture and Storage （CCS） technology is one of the effective ways to offset global warming and reduce CO₂ emissions, and its potential assessment is crucial. The CCS technology mainly includes four types: CO₂ storage in depleted oil and gas reservoirs, CO₂ enhanced oil/gas recovery, CO₂ enhanced coal bed methane and CO₂ storage in saline aquifer. The CO₂ storage in depleted oil and gas reservoirs, in which depleted oil and gas reservoirs have good trap structures and geological conditions are very suitable for CO₂ storage. Oil and gas exploration in North South China Sea has been developed for half a century, and there are five gas zones have been built, including Liwan Gas fields, Dongfang Gas fields, Ledong Gas fields, Yacheng Gas fields and Lingshui Gas fields. The construction of the “trillions square meter gas zone in the South China Sea” is steadily advancing. At the same time, the production of some gas fields have entered the final stage （depletion period）, and the CO₂ content of these gas fields is high. Based on the geological characteristics of these gas fields, according to the known natural gas production, the effective storage capacity of CO₂ is calculated. The results show that the CO₂ effective storage capacity of YC13-1 and DF1-1 gas fields is 1.2×10⁸ t and 2.3×10⁸ t, demonstrating considerable CO₂ storage potential. The research results can provide technical support for the selection of offshore carbon storage targets.