考虑地层水存在的高温高压凝析气藏相态研究

Study on the effect of formation water on the phase behavior of the hydrocarbon-water system in high-temperature and high-pressure condensate gas reservoir

高温高压凝析气藏地层水的存在对相态和开发动态的影响不容忽略.基于活度系数模型并结合PR状态方程,建立了考虑地层水的烃水体系气-液-液三相相平衡计算模型.针对实例凝析气藏,通过实验和理论模拟手段研究了地层水存在时温度和压力对凝析气中水含量、油气水三相相体积、饱和压力、p-T相图以及反凝析液量的影响规律.研究结果显示,温度越高气中凝析水含量越高,而且随压力降低呈指数增加.地层水存在使凝析气藏露点压力和最大反凝析液量均增加,这说明地层水存在加剧了反凝析.考虑地层水存在的烃水体系p-T相图更能反映油气水三相相态特征.由此可见,高温高压凝析气藏必须考虑地层水存在对相态及开发过程可能带来的影响.

The effect of formation water on the phase behavior of the hydrocarbon-water system and the development dynamic in high-temperature and high-pressure condensate gas reservoir cannot be neglected.Three phase equilibrium model of hydrocarbon-water system is established based on activity coefficient model and PR EOS.A gas condensate reservoir being taken as an example,the influencing laws of the formation temperature and pressure on the content of water,the phase volumes of oil,gas and water,saturation pressure,p-T phase diagram and the amount of retrograde condensed liquid are studied by experiments and theoretical simulation.It is shown that the higher the formation temperature,the higher the content of the condensate water in gas,and the content of the condensate water in gas will increase exponentially with the decrease of the formation pressure.The existence of the formation water makes the dew-point pressure and the maximum retrograde condensed liquid amount of the condensate gas reservoir,which shows that the existence of the formation water enhances the phenomenon of the retrograde condensation.The p-T phase diagram of hydrocarbon-water system under considering the existence of the formation water can well reflect the three-phase characteristics of the oil-gas-water.Therefore,the effects of the formation water on the phase behavior and development process of the high-temperature and high-pressure condensate gas reservoirs should be considered.