凝析气井井筒压力计算

准确计算凝析气井井底压力是正确预测产能、合理制订生产方案的关键,近年来凝析气井压力计算重点考虑黑油模型和组分模型的差异,而对优选气液两相管流压降模型的重要性却认识不足。为此,采用Govier-Fogarasi公开发表的94口凝析气井实验数据对工程常用的无滑脱模型、HagedornBrown、Orkiszewski、Gray、MukherjeeBrill、HasanKabir分别按黑油模型和组分模型预测井筒压力。井底流压和压降梯度统计评价结果表明:两相流模型的选择对凝析气井井筒压力预测结果影响较大,而组分模型和黑油模型对部分两相流模型在一定条件下对凝析气井井筒压力计算产生影响;推荐使用Gray模型+黑油模型和HagedornBrown模型+组分模型来预测凝析气井压力剖面,并给出了无滑脱模型的适用条件(液气比为0.5~5m3/104 m3、产气量大于5×104 m3/d);最后指出,采用组分数据计算凝析气井压力剖面时,其数据选择尤为重要,否则预测的误差会增大。该研究成果对于凝析气藏的高效开采具有重要的意义。

Calculation of the wellbore pressure of a condensate gas well

Calculating the downhole pressure of a condensate gas well accurately is the key to predicting the well′s productivity and making a reasonable production plan. In recent years, the calculation of condensate gas well pressure only focuses on the differences between the black oil model and the compositional model, which ignores the significance of the gas liquid pipe flow pressure drop model optimization. Thus, the experimental data from 94 condensate gas wells published by Govier Fogarasi was used to predict the wellbore pressure of a slip free model and five gas liquid flowing models (Hagedorn & Brown, Orkiszewski, Gray, Mukherjee & Brill, and Hasan & Kabir). Statistical evaluation of downhole flowing pressure and pressure dropping gradients indicated that the selection of gas liquid flow model affects the prediction results of wellbore pressure in a condensate gas well. Moreover, the compositional model and black oil model have an effect on the calculation of wellbore pressure in a condensate gas well by partial gas liquid flow models under certain conditions. So Gray model + black oil model and Hagedorn & Brown model + compositional model are recommended in predicting the pressure profile of a condensate gas well, and the application conditions of the slip free model are provided, such as the liquid gas ratio ranges from 0.5 to 5 m³/10⁴ m³, the gas production rate up to 5×10⁴ m³/d. Finally, it was pointed out that the data for calculating the pressure profile should be first selected, if not, the prediction error would be greater than expected. These research findings are of great significance to the high efficient development of condensate gas reservoirs.