综合高速效应的凝析气藏流入动态

当井底压力低于露点压力时,凝析液在近井地带开始析出并不断聚集产生凝析油堵塞现象。因此,在制定凝析气井工作制度时,通常以控制生产压差为指导思想,往往忽略高速流动下凝析气液相变的非平衡特征。对于凝析气体系,当外界温压变化速度超过凝析气液的相平衡速度时,凝析气体系相变滞后,开始呈现非平衡特征,即凝析液的析出量随着压降速度的增加而减小。凝析气在向井筒流动的过程中,近井区高速流动使凝析气产生非平衡相变,凝析气在比较高的压降速度下流入井筒,使得凝析液来不及析出。在分析非平衡相变规律与近井地带凝析气渗流参数分布的基础上,评价凝析气液流动过程中的非平衡特征,给出了考虑非平衡相变的凝析液饱和度分布计算公式,并进行了产能预测结果对比。实例分析表明,可以通过适当放大生产压差,增加凝析气液相变非平衡特征,减小井筒附近的凝析液饱和度,提高气井产能与气藏开发效果。

Study on inflow performance relationship of condensate reservoir considering high velocity flow effect

The exist of condensate oil saturation formed when the PBH is lower than the dew point pressure will reduce deliverability of gas condensate well.So,to control the pressure difference becomes the principle of production system determination for gas condensate well,which neglects the effect of non-equilibrium phase change caused by high velocity flow.The phase change of gas condensate system shows its characteristic of non-equilibrium when the temperature and pressure change rate of the environment exceed the phase change rate of gas condensate system.It has been found in numerous experimental researches that non-equilibrium phase change effect caused by high velocity flow have noticeable effect on condensate oil saturation within the immediate vicinity and productivity of the well.Condensate oil can't be produced immediately with high rate of pressure drop.Based on non-equilibrium phase change law and the distribution of flow parameters near well bore,the non-equilibrium effect of gas condensate flow is evaluated in the paper.The formula considering of non-equilibrium phase change effect is presented for the calculating the distribution of condensate oil saturation.By contrast of different inflow performance relationship models and condensate oil saturation distributions,it is indicates that to enlarge the pressure difference can increase the productivity by enhancing the effect of non-equilibrium phase change and decreasing the condensate oil saturation.