Screening and simulation of offshore CO2-EOR and storage: A case study for the HZ21-1 oilfield in the Pearl River Mouth Basin, Northern South China Sea

•Couples of multiparameter screening and compositional simulation are useful for site optimization for CO2-EOR and storage.•Miscible CO2 flooding with one or two injection wells are the best operation for M10 reservoir.•Well pattern and bottom pressures of CO2 injection control the mechanism and efficiency of CO2 flooding.•HZ21-1 field has considerable potential for applying offshore CO2-EOR and CO2 storage technology of Guangdong CCUS project.