含CO2天然气黏度计算模型及影响因素研究

Study on the Calculation Model and Influencing Factors of the Viscosity of Natural Gas Containing CO

CO2相变会导致天然气黏度变化异常复杂,应用实验手段测量含CO2天然气黏度数据具有一定困难,因此需要在已有黏度实验数据的基础上建立相关计算模型进行预测。根据含CO2天然气黏度的预测方法,对比计算气体黏度的LBC、DS、LGE、Lucas等4种模型在预测CO2气体黏度时的准确性。通过计算比较发现,LGE黏度计算模型误差较大,而DS方法能较准确地确定含CO2天然气的黏度。应用DS模型对含CO2天然气黏度进行计算,计算结果表明:压力升高时,气体黏度就会增大;相同温度、压力条件下CO2含量越高,黏度越小。以上结论对研究超临界CO2热物理性质、揭示井筒流动规律、油气相变预测具有重要意义。

CO2 phase change will cause extremely complicated change of natural gas viscosity.It is difficult to apply experimental methods to measure natural gas viscosity data.The accuracy of the existing CO2 natural gas viscosity calculation model is not high.Therefore,it is necessary to establish a relevant calculation model based on the existing experimental data for prediction.According to the prediction method of CO2-containing natural gas viscosity,the accuracies of four models including LBC,DS,LGE and Lucas for calculating the viscosity of gas were compared.Through calculation and comparison,it was found that the error of the LGE viscosity calculation model was large,and the DS method could determine the viscosity of the gas containing CO2 more accurately.Through analyzing the influencing factors,it was found that the gas viscosity increased when the pressure increased;the higher the CO2 content at the same temperature and pressure,the lower the viscosity.The above research is of great significance for revealing the wellbore flow law and the prediction of oil gas phase change.