凝析气藏产能评价方法研究

该文从凝析气藏渗流与油气分布“三区”特征出发，建立了更符合实际渗流特征的凝析气藏产能预测方程。首先将凝析油气分布分为单相气无凝析油区、单相气凝析油不流动区及凝析油气两相渗流区，并建立了相对应的渗透率模型。在此基础上考虑了自由凝析气、自由凝析油、溶解凝析气、溶解凝析油的影响，建立了不同区域凝析气藏产能预测方程。最后，结合等组分膨胀试验以及渗流特征，求解两相拟压力，两相高速非达西系数以及平均自由油气比，得到两相产能方程系数，实现对产能方程求解。研究不同凝析油含量下的产能特征发现，与低凝析油含量相比，高凝析油含量下的拟压力小、高速非达西系数大、IPR曲线有明显的拐点，气井无阻流量显著减少。实例证实近井地层凝析油析出对气井产能有巨大影响，即使少量的凝析油析出，也会造成产能方程系数增大，并大幅度减少产能。该文的研究对凝析气藏的产能评价有指导意义。

Research on Productivity Evaluation Method of Gas-Condensate Reservoirs

Based on "three zones" characteristics of flow and retrograde condensation behavior of gas-condensate reservoir, the productivity prediction equation of condensate gas reservoir is established in line with the actual. Firstly,the distribution of condensate oil and gas is divided into three zones: gas flow with no condensate, gas flow with no condensate flow and gas-condensate flow, and the corresponding permeability model is established. On this basis, considering the influence of free gas, free condensate, dissolved gas and dissolved condensate, the productivity prediction equations of condensate gas reservoirs in different regions are established. Finally, combined with the CCE experiments and flow, the two-phase pseudo-pressure, the two-phase Non-Darcy coefficient and average free condensate-gas ratio and the performance are calculated, which is obtained to realize the solution of the productivity equation. By studying the productivity characteristics of different condensate oil content, it is found that compared with lean condensate oil content, the pseudo-pressure of rich condensate gas reservoir is much smaller, and Non-Darcy coefficient is much larger. What's more, the IPR curve has an obvious turning point, making the gas well open-flow capacity significantly reduced. The example proves that the condensate oil precipitation in near-well formation has a great influence on gas well productivity. Even a small amount of condensate oil precipitation will increase the productivity equation coefficient and greatly reduce the productivity. The research has guiding significance for the productivity evaluation of condensate gas reservoirs.