Abstract: Underwater storage facilities， leveraging oil-water displacement technology， serve as independent storage units that provide diversified media storage at sea and are essential for the development and utilization of marine energy. This paper analyzes five potential application scenarios for future underwater storage facilities， including the development of marginal oil fields in shallow waters， underwater energy storage technology， underwater methanol and ammonia storage technology， underwater carbon dioxide storage technology， and the storage and injection technology of chemical reagents on the seabed. In marginal oil fields， a combined approach using an integrated processing platform， underwater storage facilities， and shuttle tankers can enhance cost adaptability and the flexibility of storage capacity customization. Underwater energy storage technology (underwater compressed air energy storage and underwater hydrogen storage) is provided for offshore wind platforms to ensure the stability of power transmission and reduce the limitations of storage space on the platform. Offshore wind power can also be converted into methanol and ammonia， by adopting underwater storage solutions. The storage units on the platform can be canceled， thereby reducing overall investment. By installing LCO2 storage facilities underwater instead of storing it on the injection platform， the efficiency of LCO2 storage and its environmental adaptability can be improved. The use of seabed chemical reagent storage and injection technology significantly enhances the safety， cost-effectiveness， and injection accuracy of the chemical reagent system.

Key words: oil-water displacement, underwater storage tanks, oil and gas development, underwater energy storage, seabed chemical reagent storage