Storing CO₂ for geological timescales is crucial to delivering decarbonisation of industrial economies aligned with global climate change mitigation objectives. This requires CO₂ injection into a large subsurface pore space overlain by a high capillary entry pressure seal rock to prevent CO₂ escape. Such formations occur abundantly in productive hydrocarbon basins such as the North Sea. However, these geological conditions for CO₂ storage are unavailable close to some large CO₂ emitting economic areas in China. We identify this problem and innovate a solution for the example of the Pearl River Mouth Basin (China). This offshore basin has an estimated effective storage capacity of hundreds of Gt CO₂ based on reservoir pore volumes. Production and geological data of three oil fields of the Huizhou hydrocarbon cluster are analysed as analogues for large-scale aquifer storage of CO₂. Results suggest the injection and storage of CO₂ in individual trap structures will perform poorly, due to thin reservoir layers, small structural traps, and indications that the cap rocks may have only limited sealing capability. To address this a novel alternative CO₂ sequestration strategy, based on multi reservoir layer injection and dispersion trapping, is recommended to exploit the vast available pore space for CO₂ storage.