富含凝析油的凝析气藏注CO_(2)相态特征研究

Study on Phase Characteristics of CO_(2) Injection in Condensate Gas Reservoir Rich in Condensate Oil

对于富含凝析油的凝析气藏,注CO_(2)是较为有效的开发方式,但目前对其开发机理和规律的认识不够充分。通过膨胀实验和气液两相平衡理论,分析了在富含凝析油的凝析气藏中注入CO_(2)后对地层流体相态的影响。研究结果表明:随着CO_(2)注入比例的增加,流体体系从挥发油体系逐渐过渡到常规凝析气体系;在最小混相压力条件下,处于开发中后期的凝析气藏,可实现多次接触混相,能有效解除气井近井地带反凝析污染,从而提高气藏采收率。

For condensate gas reservoirs rich in condensate oil,CO_(2) injection is an effective development method,but the current understanding of its development mechanism and law is not enough.The effect of CO_(2) injection on the phase state of formation fluid in a condensate gas reservoir rich in condensate oil is analyzed based on expansion experiment and gas-liquid equilibrium theory.The results show that with the increase of CO_(2) injection ratio,the fluid system gradually transitions from volatile oil system to conventional gas condensate system.Under the condition of minimum miscible pressure,multiple contact miscibility can be realized in the middle and later stage of the gas condensate reservoir,which can effectively remove the back condensate pollution near the well zone,thus improving the gas reservoir recovery.