Dynamic Analysis of the Tubing String in Injection/Production Wells of Gas Storage
摘要
In the injection and production operations of gas storage wells, the rapid flow of natural gas inside the tubing string often easily causes vibration of the tubing string. The alternating stress caused by this vibration poses a potential threat to the oil pipe column and its threaded connections, which may exacerbate their loading conditions, leading to gas leakage and column failure, and affecting the safe and stable operation of gas storage wells. In order to ensure the safety and efficiency of gas storage wells during the injection and production process, this paper constructs a dynamic analysis model of the pipe column for injection and production conditions. By using this model and combining it with the measured data of typical wells on site, we conducted an in-depth analysis of the vibration characteristics of the pipe string and the sealing performance of the threaded connection under injection production conditions. Research has found that: ① When avoiding resonance gas conditions, as the injection and production volume increases, the vibration frequency, velocity, and acceleration of the pipe column also increase accordingly. The vibration amplitude is most significant in the upper 300–500 m section of the packer, which poses a risk of collision with the wellbore wall. This provides theoretical support for the optimal placement of the vibration tester. The vibration of the tubing string can alter the axial force distribution of the tubing, and its maximum value may not occur at the wellhead position. Under injection production conditions, the safety factor will be reduced by approximately 20% compared to static conditions When the gas volume during the injection and production process exceeds 2.5 million cubic meters/day and 2 million cubic meters/day respectively, collision may occur between the oil pipe and the casing Within the current injection and production range, the strength of VAM-TOP FJL threads can meet the usage requirements. In summary, under the premise of avoiding resonance gas volume, oil pipes with an outer diameter of 114.3 mm and a wall thickness of 6.88 mm can ensure the safe production of gas storage wells within the range of injection and production volume of 0.5–2 million cubic meters per day.