Abstract: The depletion experiments on practical condensate gas samples were carried out by means of PVT cells and cores. The results of experiments show that recovery efficiency of condensate oil in PVT cells is lower than that in cores. In order to investigate the difference of recovery efficiencies of the experiments, the critical flow saturation of condensate gas in core was tested. The conventional relative permeability curves of kerosene displacement with N₂ and the equilibrium oil-gas relative permeability curves at high pressure and high temperature were developed. The two kinds of curves and GEM software were respectively used to simulate the depletion experiments in PVT cells and cores. The simulation results show that the recovery efficiency of condensate gas predicted with conventional relative permeability curve is close to that in PVT cells. The recovery efficiency of condensate oil predicted with equilibrium oil-gas relative permeability curve is close to that with the depletion experiments in core. The equilibrium oil-gas relative permeability curves can express the state of condensate gas flowing in cores.

Key words: condensate gas reservoir, condensate oil, critical flow saturation, recovery efficiency, relative permeability curves

摘要： 采用实际凝析气体系分别在PVT筒和实际岩心中进行了衰竭实验。研究结果表明,PVT筒比岩心中衰竭实验凝析油采收率低得多。为了探讨造成凝析油采收率差别的原因,首先测试了临界流动饱和度,继而做出了标准常规相渗曲线(氮气驱煤油)以及平衡油和平衡气在高温高压下相渗曲线。利用两种相渗曲线及GEM油藏模拟软件分别对实验结果进行了预测。结果表明,采用常规相渗曲线所预测的凝析油采收率与PVT中凝析油采收率相近,采用平衡油气相渗曲线所预测的凝析油采收率与用岩心衰竭实验测试的凝析油采收率相近,这表明平衡相渗曲线能够较好地反映实际岩心条件下油气的渗流状况。

关键词: 凝析气藏, 凝析油, 临界流动饱和度, 采收率, 相对渗透率曲线