采用凝析油气测量凝析气藏相对渗透率

USING CONDENSATE GAS TO SURVEY RELATIVE PERMEABILITY OF CONDENSATE RESERVOIRS

由于缺乏精确测量临界凝析油饱和度测试技术 ,我国凝析气藏油气相对渗透率均使用常规油气进行测试 ,采用真实平衡凝析油气体系对凝析气藏相对渗透率曲线进行岩心驱替测试还无先例。文章选用牙哈凝析气藏真实岩样进行了两组驱替实验 ,第一组是向岩样注入煤油 -氮气采用非稳态法 ,第二组是注入平衡凝析油气采用稳态法。此外 ,研究了两种测试系统下油气相对渗透率对凝析气藏开发动态的影响 ,得出以下结论 :①凝析油气系统的相对渗透率曲线整体向右移动 ,气相对渗透率下降非常快 ,油气相对渗透率高于煤油 -氮气系统的油气相对渗透率 ;②凝析油气系统的临界凝析油饱和度比煤油 -氮气系统的凝析油临界饱和度约低 2 0 % ;③煤油 -氮气系统预测的气体产能、气油比、凝析油气采收率比凝析油气系统预测的结果低得多 ,但气藏压力下降较慢 ;④凝析油气系统与煤油 -氮气系统近井地带析出凝析油饱和度分布存在显著差别。

Since without testing techniques to survey the critical condensate saturation accurately, the relative permeability of condensate reservoir is tested usually with conventional oil and gas in China. It has not been done before to conduct core displacement test with real balanced condensate system for the relative permeability curve of condensate reservoirs. With real cores of Yaha condensate reservoir, two groups of displacement tests have been conducted. For the first group, Kerosene-nitrogen is injected into the core with astatization method. For the second group, balanced condensate gas is injected into the core with steady state method. The influence of oil and gas relative permeability on the production performance of condensate reservoir is studied. And the following conclusions are acquired:① Comparing with the relative permeability curve of Kerosene-nitrogen system, the relative permeability curve of gas-condensate system moves rightwards and the gas relative permeability decreases quickly;② The critical condensate saturation of gas-condensate system is 20% lower than that of Kerosene-nitrogen system;③ The gas productivity, GOR, condensate recovery predicted with Kerosene-nitrogen system is much lower than that predicted with gas-condensate system, but the reservoir pressure decreases slower;④ Gas-condensate system differs greatly from Kerosene-nitrogen system in condensate saturation distribution at the near well-bore area