Finite element simulation and vibration characteristics analysis of two-way FSI in gas storage tubular strings

Abstract During gas storage injection and production operations, high-speed gas flow continuously impacts the completion string, easily triggering strong vibrations and leading to fatigue failure, which seriously threatens downhole safety and production continuity. To address this issue, this study establishes a transient finite element model of a 30 m section of Φ88.9×6.45 mm P110 tubing under 40 MPa high-pressure conditions based on two-way fluid-structure interaction (FSI) theory, and systematically conducts a detailed finite element simulation analysis of the string’s vibration characteristics. Finite element calculation results indicate that fluid pressure is the dominant factor causing significant radial expansion in the central section of the string, while wellhead and wellbottom constraints lead to high-risk stress concentration at the ends. Under thin-wall conditions, finite element simulations show that deformation and stress increase by 53% and 51%, respectively, compared to standard conditions. Under thin-walled, high-pressure conditions at 60 MPa, finite element method simulations reveal that deformation and stress increase by 53% and 51%, respectively, compared to the 40 MPa condition. Under the same high-pressure environment, two-way FSI consistently results in higher radial deformation and stress values in the tubular string compared to one-way FSI. Based on these finite element numerical results, the study provides critical theoretical support for the safety design and risk mitigation of gas storage tubular strings.