近临界凝析气藏相态特征与开发方式研究

The Research on Phase Behavior and Development Scheme of Near-critical Gas Condensate Reservoir

结合非洲J气藏流体资料,分析了近临界凝析气藏的相态特征;并利用油藏数值模拟技术,研究了此类气藏所适用的开发方式。研究发现近临界凝析气藏具有凝析油含量高、相态变化敏感性强、反凝析严重的特征。采用衰竭式开采的方式,凝析油损失严重,开发效果差;水气交替开采可以有效地控制反凝析,获得较高的采油速度;同时避免了单纯注水开发中含水上升过早过快的问题,兼具注水和注气的优点,为最优的开采方式。进一步研究水气交替开采的敏感性因素发现,水气比对开发效果的影响最大:水气比过高,注入水易过早突进到井底;水气比过低,不能发挥注水驱替保压、提高凝析油采油速度的优势。

Combined with fluid data of J gas reservoir in Africa,the phase characteristics of near-critical gas condensate reservoir were studied,and the applicable development technique were analyzed using reservoir numerical simulation.The results show that the near-critical gas has the following characteristics.It has a high content of condensate oil,the sensitivity of phase is strong,and the degree of retrograde condensation is high.Depletion type of recovery results in great loss of condensate oil and poor production,the method of water-oil alternating recovery could control the level of condensate effectively and get a high oil production rate.In addition,it avoids the rising up of water cut too early and quickly in the method of water flooding.Water-oil alternating recovery is the best producing method which combined the advantages of water injection and gas injection.Further study on sensible factors in water-oil alternating recovery indicates that the water / gas ratio（WGR） has the greatest impact on production effect.When the WGR is too high,injected water will rush into the well bottom too early;when the WGR is too low,the advantage of water injection to displace and provide pressure is lost,and condensate oil production rate can＇t be enhanced.