Objective To overcome the limitations of traditional oil storage methods—such as extensive land use, high costs, limited site options, safety and environmental risks, and lack of flexibility—this study introduces the innovative concept of flexible oil storage in waters. By utilizing expansive water spaces and flexible materials, a land-independent oil storage solution is developed, offering enhanced safety, cost-effectiveness, adaptability, and deployment flexibility. This approach aims to support the development of a diversified and resilient national petroleum reserve system in China.

Methods The advantages and disadvantages of existing storage methods, including onshore tanks, geological storage, and rigid waterborne tanks, were systematically reviewed. Based on first-principles analysis, the oil storage scheme was distilled into two key technical paths: utilizing natural water bodies as storage bases and employing flexible composite oil bladders to achieve reliable oil-water isolation. The innovative mechanism of “replacing underground pore-water sealing with complete water sealing, replacing geological support with water buoyancy support, and replacing rigid tanks with flexible oil bladders” was elucidated. Finally, systematic research on key technologies for pollution prevention and control, as well as the design, operation, and maintenance of flexible oil storage in waters, was conducted through a combination of theoretical derivation, numerical simulation, and model testing.

Results Application cases of underwater oil storage and flexible bladder energy storage devices confirmed the feasibility of flexible oil storage in waters. For pollution prevention, the bladder material’s oil permeation rate standard meeting water quality requirements was established; an active anti-seepage technology using a biochar adsorption layer was developed; and a leakage trajectory prediction model along with emergency response strategies were formulated. For design, operation, and maintenance, the elliptical bladder was validated as the optimal configuration; the damage evolution mechanism of flexible waterborne oil storage was identified; and the cross-shaped six-cable constraint demonstrated excellent performance in controlling impact displacement, regulating anchor cable tension, and suppressing structural vibration.

Conclusion As an innovative storage paradigm, flexible oil storage in waters is expected to overcome the shortcomings of traditional methods and offer broad application prospects. However, the technology remain in the laboratory research stage, with its performance evolution and failure mechanisms under long-term hydraulic pressure, fluctuating temperatures, and extreme loads such as typhoons and sea ice not yet fully understood. Further research is required to accelerate engineering demonstration and industrialization, and to improve technical standards and specifications, enabling it to become a reliable option for safeguarding national energy security.