Integrated structural and thermal analysis of subsea storage tanks: wall thickness design, transient heat transfer, and parametric fitting across multiple depths

Driven by growing global demand for oil and gas resources, the development of offshore oil and gas fields has experienced significant expansion, requiring immediate solutions for large-scale offshore resource storage. Compared to platformbased storage and shuttle tanker operations, subsea oil storage has emerged as a prominent research focus in recent years due to its enhanced efficiency and economic viability. However, current deep-sea subsea oil storage faces critical challenges, primarily stringent structural strength requirements and the inability to ensure crude oil flowability during extended storage periods. To address the above challenges, this study conducts coupled structural and thermal analysis on subsea oil storage tanks under water depths of 100-1,200 m. For each depth condition, the required wall thickness is first calculated according to GB/T 150.3-2024 and then validated using finite element analysis (FEA). Subsequently, transient heat transfer simulations are conducted under each condition to calculate the temporal evolution of oil temperature, heat dissipation power, and average heat flux density for varying insulation layer thicknesses and determine the required thickness of thermal insulation material. Finally, based on the calculation results, empirical correlations are derived to allow quick calculation of wall thickness and insulation layer thickness under varying water depths. The results establish the governing principles for structural integrity constraints and thermal insulation specifications in deep-sea environments, delivering a rigorous design basis for subsea storage tank engineering.