Research On Simulation Application Of Long Distance Supercritical CO₂ Pipeline Transportation

In order to cope with global warming,energy conservation and emission reduction have become a hot topic in the world today.In the field of energy,CCUS（carbon capture,utilization and storage）is one of the key technologies to cope with global warming.CO₂flooding has become the main measure to improve oil recovery in old oil fields.To this end,this paper makes a series of studies applicable to the long-distance CO₂ pipeline transportation of 160km of carbon dioxide pipelines that are piped to the oil displacement point after CO₂capture in a domestic oilfield natural gas purification plant.Firstly,after investigating a large number of domestic and foreign experimental data and research progress,this paper chooses the P-R state equation suitable for carbon dioxide phase and physical property analysis.Unisim software was used to simulate the phase state and physical properties of pure CO₂,and the effects of impurities（CH₄,H₂,H₂S,O₂,N₂）on the CO₂ fluid were simulated and compared in detail.Subsequently,analyzed the characteristics of the CO₂ fluid in the gas source of this project.Secondly,analyzed the process and characteristics of gas phase,liquid phase and supercritical phase CO₂ pipeline transportation technology.PIPEPHASE software is used to simulate the CO₂ pipeline transportation scheme of the project under three phases,and analyzed the pressure along the pipeline under each phase.Analyzed parameters such as pressure and temperature along the pipeline and phase changes under each phase.By considering aspects such as operation safety and investment cost,a supercritical CO₂ pipeline transmission method suitable for this project is proposed.Then,OLGA software was used to perform steady state simulation of the proposed supercritical pipeline transportation scheme,The effects of relevant operating parameters（actual output adjustment,starting pressure and starting temperature）and environmental factors（environmental temperature,total heat transfer coefficient,and height difference）on the supercritical CO₂ transport system are analyzed.They set constraints on the design of actual pipeline systems.Finally,on the basis of steady-state transportation,transient simulation methods were used to simulate the transient conditions（changes in gas source throughput,pipeline shutdown and restart,pipeline leakage and blockage,and pipeline emptying）encountered in the actual transportation process.Analyze the impact of transient operating condition changes on the supercritical CO₂ long-distance pipeline system.They give limited conditions for operating conditions in actual transportation.The above research aims to provide theoretical support for the design of long-distance supercritical CO₂ pipelines,and to provide guidance and recommendations for long-distance supercritical CO₂ pipelines.