通过润湿反转提高凝析气产量

Enhancing Gas-condensate Production by Wettability Alteration to Gas Wetness

许多凝析气藏产气量急剧下降,这取决于井底压力低于露点压力时的凝析量。用低渗透岩芯做了多次实验,实验室已成功的演示了润湿反转过程。被井筒附近的凝析损伤了的凝析气藏通常具有较低的渗透率。在本研究中,我们用了试验油田(X油田)的岩样来进行实验。首先用一种便宜的新型化学试剂有效改变岩芯的润湿性从水湿到气湿,试剂恒温在170℃。实验结果表明盐浓度较高时这种化学试剂更有效。第二,在恢复过程中通过渗吸实验来验证润湿反转效果。第三,在优先进行气润湿反转之前先测试气水相对渗透率值。实验结果表明优先进行气润湿之后气相和水相的相对渗透率都增加。润湿反转之后束缚水饱和度降低,气体产量有明显增加。

Many gas-condensate reservoirs experience a sharp drop in gas production due to the condensation near the wellbore when bottomhole pressure is lower than dew point pressure. Through experiments of real reservoir rocks with low permeability, wettability alteration approach has been successfully demonstrated in laboratory. The gas-condensate reservoirs impaired by the condensation near the wellbore usually have low permeability. In this paper, experiments of the rock sampled from the target gas field were carried out. Firstly a new and cheaper chemical reagent was used to change the rock wettability from water-wetness to gas-wetness effectively. The temperature of this chemical reagent was controlled at 170 ~C. Experimental results show that, the higher the salinity, the better this chemical reagent＇s effect. Secondly spontaneous water imbibition tests were used to show the effect of wettability alteration. Thirdly relative permeability data of gas phase and water phase were measured before and after wettability alteration to preferential gas- wetness. Experimental results show that the relative permeabilities of the gas and the water phases increase significantly after the wettability alteration to preferential gas-wetness; the residual water saturation decreases and the gas production increases greatly due to the wettability alteration.