让纳若尔A南凝析气藏在正式开发前已发生严重的反凝析,造成凝析油损失严重。探索提高凝析油产量方法对油田下一步开发显得尤为重要。为此,以A南某典型井为例,应用相平衡理论和油藏数值模拟技术,分析了地层流体反凝析规律和凝析油分布特征,研究了CO₂吞吐提高气井凝析油产量机理及效果。结果表明,气藏反凝析分为恒质膨胀和定容衰竭2个阶段,凝析油主要聚集在井筒周围30 m内,凝析油饱和度范围22.44 %~29.51 %。CO₂提高凝析油产量的机理主要是改变地层流体反凝析规律、降低反凝析界限和蒸发凝析油。但当CO₂注入量较少时,CO₂蒸发凝析油能力有限。为确保CO₂吞吐增油效果,CO₂的周期注入量应该超过500×10 ⁴ m ³。该研究对类似凝析气藏开发中后期提高凝析油产能及解堵具有指导意义。

Serious retrograde condensation has occurred before the development of gas cap in South A condensate gas reservoir of Zanarol Oilfield, resulting in serious loss of condensate oil. It is particularly important to explore the method of improving the production of condensate oil for the further development of oilfield. Therefore, taking a typical well in South A gas reservoir as a example, the phase equilibrium theory and numerical simulation are applied to study the retrograde condensation rule of formation fluid and the distribution of condensate oil in formation. On this basis, the mechanism and effect of condensate oil enhancement by CO₂ huff-n-puff are researched. The results show that retrograde condensation in South A gas reservoir has two stages: constant composition expansion（CCE） and constant volume depletion（CVD）. Condensate oil distributes mainly within 30 m of wellbore, and its saturation ranges from 22.44 % to 29.51 %. The mechanism of CO₂ increasing condensate production is to change the retrograde condensation rule, reduce pressure condition of retrograde condensation, and evaporate condensate oil. However, if the injection volume of CO₂ is low, the volume of vaporized condensate oil will be small, which limits the effect of EOR. Therefore, the cumulative injection of CO₂ should be more than 500×10 ⁴ m ³ at a cycle to ensure the effect of CO₂ huff-n-puff. This study has guiding significance for condensate oil enhancement and plug removal in the middle and later stages of similar condensate gas reservoir development.