大涝坝凝析气藏注气开发相态机理研究

大涝坝凝析气田是位于塔里木盆地的深层、高温高压、高含蜡、高含凝析油的凝析气藏,采用衰竭式开发,气藏反凝析现象严重,大量凝析油滞留地层中。根据注入外输气与地层反凝析油之间的相态变化特征研究表明注入外输气与反凝析油在多次接触过程中通过溶解-抽提作用进行相间传质,使油气体系组成、性质发生明显变化;注气可使地层中反凝析油蒸发,同时有效改善凝析油的流动性质,使膨胀系数增加、凝析油粘度和密度下降、气液相界面张力显著降低,有利于提高凝析油的采收率。

Phase mechanism of gas injection in Dalaoba Gas Condensate Field

The Dalaoba Gas Condensate Field is a deep,high temperature,high pressure,high waxcontent and high condensate oil content reservoir in the Tarim Basin.Natural depletion production hasbeen carried out,and a large quantity of gas has condensed and remained in formation as condensate oil.Phase changes of injected gas and condensate oil in formation were studied.When injected gas metcondensate oil,interphase mass transfer took place due to dissolving and extracting effects,resulting inobvious changes of the composition and characteristics of petroleum system.Condensate oil in formationevaporated and the mobility of condensate oil was also improved.Expansion coefficient increased,viscosity and density decreased,and gas-liquid interfacial tension decreased.All these helped toimprove oil recovery rate.