致密气藏气水相对渗透率理论及实验分析

Theoretical and Experimental Analysis of Gas-Water Relative Permeability in Tight Gas

通过设计不同压差下的气水驱替实验,得到了不同驱替压差下的气、水两相驱替特征及相对渗透率曲线。并基于分形理论,考虑了束缚水饱和度及驱替压差的影响,建立了致密砂岩气水相对渗透率计算模型,求解得到了气水相对渗透率的解析公式。模型计算得到的相对渗透率与实验结果吻合度较高,从而验证了模型的正确性。研究表明,气、水相对渗透率曲线受到驱替压差和孔隙结构参数的影响。随着驱替压差增大,束缚水饱和度降低,两相区域变宽,水相相对渗透率升高。

The effect of drawdown pressure on relative permeability is theoretically and experimentally investigated in this paper.A novel predictive model for gas-water relative permeability on the basis of the fractal theory was derived and the corresponding gas flooding tests were conducted.The predictions of relative permeability by the proposed model were validated by comparing with the conducted experiments.Both theoretical and experimental results indicate the significant effect of driving pressure on relative permeability.The predicted and experimental results demonstrate that lower immobile water saturation,wider two-phase region and higher water relative permeability corresponds to the higher drawdown pressure.