Abstract:

The critical condensate saturation is a key parameter to reflect condensate flow capacity, and it has a significant impact on condensate recovery, gas-well productivity and stable production period. Therefore, the critical condensate saturation has been continuously a hot issue in researches both at home and abroad. A new method was established to determine the critical condensate saturation by means of a long-core displacing apparatus and a gas chromatograph. Applying this method, two experiments were performed on a real core from a condensate reservoir and on a C₁~C₅ mixed fluid, their critical condensate saturation was 3.04% and 4.66%, respectively. The results obtained from analyses on flow characteristics of condensates indicated that the critical condensate saturation was very low. The comparison of the two experiments showed that porous media would raise the dew pressure of fluids, and both irreducible water and large difference in pressure were conducive to the flow of condensates. Finally, this low critical condensate saturation was verified using a numerical simulation.

Key words: condensate reservoir, critical condensate saturation, experiment, flow characteristics, irreducible water

摘要：

凝析油临界流动饱和度是反映凝析油流动能力的重要参数，它对凝析油的采收率、气井的产能和稳产期均存在重大的影响，因此凝析油临界流动饱和度一直是国内外研究的热点问题。建立了利用长岩心驱替装置和色谱仪确定凝析油临界流动饱和度的方法，运用该方法对某实际凝析气藏真实岩心和C₁~C₅混合物流体进行了两组实验，测定的临界流动饱和度分别为3.04%和4.66%。凝析油的流动特征分析结果表明，凝析油的临界流动饱和度很低。两组实验的对比结果表明，多孔介质会导致流体露点压力升高，束缚水和增大压差都有利于凝析油的流动。最后，通过数值模拟研究验证了凝析油的临界流动,饱和度较低。

关键词: 凝析气藏, 临界流动饱和度, 实验, 流动特征, 束缚水