超临界含杂质CO2管网停输再启动对水合物生成的影响

Effect of supercritical impurity-containing CO2 pipe network shutdown and restarting conditions on hydrate generation

关键词:  超临界CO₂  水合物  杂质  停输再启动  影响

Key words:  supercritical CO₂  hydrate  impurity  shutdown and restarting  influence

摘要:

目的 在CO₂管道输送过程中,输送管网的工艺参数在停输再启动工况下会发生变化,容易生成水合物堵塞管网。预测和分析CO₂输送过程中水合物及水含量的生成规律,以保证管输的效率和安全性。方法 基于延长油田一期36×10⁴ t/a输送管网设计,利用OLGA软件建立超临界含杂质CO₂输送管网模型,在稳态输送下水合物生成的研究基础上,预测和分析停输再启动工况对水合物的生成位置和生成量等的影响。结果 在停输工况下,水合物生成温度和压力降低,水合物生成位置发生前移,在管网入口5 km处开始有质量浓度为0.18 kg/m³的水合物生成；而在再启动工况下,水合物生成温度增加,水合物生成量峰值为0.9 kg/m³,水合物生成区段减短且生成位置后移至管网20 km处。结论 模拟结果可以较好地指导延长油田管网设计,为管网的安全运行提供理论依据。 

Abstract:

Objective In the process of CO₂ pipeline transmission, the process parameters of the transmission pipeline network will change under the shutdown and restarting conditions, in which hydrates are easy to generate to block the pipe network. The formation rule of hydrates and water content in CO₂ transportation process is predicted and analyzed to ensure the efficiency and safety of pipeline transportation. Methods Based on the design of 360 000 tons/year transmission pipeline network of Yanchang oilfield, a supercritical impurity-containing CO₂ transmission pipeline network model using OLGA software is established. On the basis of hydrate generation under steady-state transmission, the generation location and generation effect of hydrate are predicted and analyzed. Results The hydrate generation temperature and pressure decrease under the shutdown condition, and 0.18 kg/m³ of hydrate starts to generate at 5 km to the inlet of the pipeline network. The hydrate generation temperature increases under the restarting condition, the hydrate peak generation is 0.9 kg/m³, the section is shorter and location moves back at 20 km to the inlet of the pipeline network. Conclusion The simulation results can better guide the design of the Yanchang oilfield pipeline network and provide a theoretical basis for the safe operation of the pipe network.