毛细管压力影响油气体系相平衡的理论研究与应用

THEORETICAL RESEARCH AND APPLICATION OF THE CAPILLARY PRESSURE EFFECT ON THE PHASE EQUILIBRIUM IN OIL AND GAS SYSTEM

在油气藏中 ,油气流体和储层多孔介质是一个相互作用的系统 ,油气体系相平衡计算应考虑多孔介质中的界面现象的影响。文章从热力学基本理论出发 ,建立了考虑毛细管压力的相平衡计算模型。为了论证毛细管压力对油气体系相平衡的影响程度 ,针对我国两个凝析气藏 ,分别对油气体系的毛细管压力、露点压力、反凝析液量和 p—T 相图形态进行了相态模拟计算。并利用热力学亚稳态和新相生成理论中的开尔文 (Kelvin)方程对其相态模拟计算结果作出了满意的解释。

There exists an interactional system between oil and gas fluids and porous media in oil and gas reservoirs.The effect of interface phenomena in porous media should be taken into consideration if phase equilibrium is to be calculated in oil and gas system.Based on the basic thermodynamics,phase equilibrium calculation model is set up concerning the effect of capillary pressure.In order to prove in what degree the capillary pressure has an effect on the oil and gas phase equilibrium,two condensate reservoirs in China were taken as examples to carry on phase behavoir simulation calculation of capillary pressure,dew points pressure,retrograde condensate liquid contents and P-T plase diagram of oil and gas system.The phase simulation results are well explained by using the Kelvin equation of the thermodynamic metastable state and new phase formation theory.