海上高含CO_2高含凝析油气顶油藏开发方式研究

Development Method of Offshore Gas Cap Reservoir with High CO_2 and High Condensate Oil

为制定高含CO_2高含凝析油气顶油藏的合理开发方式、提高凝析油和油环油采收率,了解高含CO_2高含凝析油的凝析气顶在开发过程中的复杂相变行为和不同开发方式对开发指标的影响。基于高含CO_2高含凝析油气体样品的室内PVT实验结果,利用Eclipse数值模拟软件模拟注CO_2和CH_4膨胀对凝析气相态的影响和不同开发方式。研究发现,CO_2和CH_4均能使凝析气体系的弹性膨胀能力增强、最大反凝析压力降低及最大反凝析油量减少;循环回注CO_2开发比衰竭开发提高油环油采收率4.3%、提高凝析油采收率约26.4%。结果表明,循环回注CO_2开发是最为合理的开发方式、开发效果最好,注水开发次之,衰竭开发效果最差。

For the purpose of plotting reasonable development method of gas cap reservoir with high CO_2 and high condensate oil,and enhancing condensate oil and oil rim recovery factor,it is necessary to study the influences of the phase changing behavior of condensate gas cap with high CO_2 and high condensate oil in the process of development and of the different development methods on development index.Based on the indoor PVT testing results of condensate gas sample with high CO_2 and high condensate oil,the process and influence of injecting swell with CO_2 and CH_4 on condensate gas phase were simulated by using Eclipse reservoir numerical simulation software,and different development methods were studied.It was found that both CO_2 and CH_4 could enhance the elastic swell capability and decrease the maximum retrograde condensate pressure as well as the peak quantity of retrograde condensate liquid,and that compared with depletion development,cycle injecting CO_2 development could raise 4.3% of the recovery factor of oil rim and 26.4% of the recovery factor of condensate oil.All the results prove that cycle injecting CO_2,as the most reasonable development method,has the best development performance;next to it is the method of injecting water;and depletion development has the worst development performance.