摘要
涠洲A油田W井区采用注干气开发,注气后压力回升、油田增产效果好,但近年油藏生产动态表明注气井存在井筒积液、各砂体采出程度不均等问题制约了注气开发效果。针对上述问题,基于相平衡理论和热力学平衡理论,运用相态恢复技术,利用纵向流体组成及特性的差异通过多次流体恢复、闪蒸和参数拟合获得了准确的流体构成及相态模型。分析了恢复后流体露点压力和气油比随平衡油添加比例的变化关系,通过添加平衡油,结合相图分析了注入气在地层条件下的流体相态,从而获得注入气随温度压力变化的真实相变,为分析注气井井底积液提供了有利依据。综合考虑注入成本、修井成本等因素后,提出先清喷,后改变注入气组分的开发方式,成功解除井筒积液,有效改善各砂体的吸气剖面,提高区块采收率1.3%。研究成果对注气开发流体相态确定、动态分析、开发方案优化等具有参考作用。
Well block W of Weizhou Oilfield A is developed with dry gas injection.After gas injection,reservoir pressure increases and oil production increase is significant.However,in recent years production dynamics of the oil reservoir suggest there are issues with liquid accumulation in the wellbore of the gas injection well and unequal production from different oil bearing sand layer that restrict the performance of gas injection development.Based on the phase equilibrium and thermodynamics equilibrium theories,application of phase recovery technology,differences in fluid composition and characteristics in horizontal direction;and after multiple fluid recovery,flash and parameter fitting,an accurate model of fluid composition and phase is developed to address the above issues.The relationship between the fluid dew point pressure and changing gas-oil ratio by adding oil in equilibrium is analysed.From the phase diagram,phase behaviour of injected gas in the formation at different temperature and pressure can be determined.This provides a favourable basis for the analysis of bottom hole liquid accumulation in the gas injection well.After considering the cost of gas injection and workover of the well,it is proposed to blow clear the injection well of the accumulated liquid first,and then inject with leaner gas after gas conditioning.This proposal successfully removes the accumulated liquid in the wellbore,effectively increases the draw down from different sand layer,and increases recovery rate of the block by 1.3%.This study results provide good reference in the determination of injected gas development fluid phase,analysis of the injected gas dynamics and optimisation of gas injection development plan.
作者
张连枝
王彦利
袁丙龙
谭舜
孙胜新
张芨强
Zhang Lianzhi;Wang Yanli;Yuan Binglong;Tan Shun;Sun Shengxin;Zhang Jiqiang(Zhanjiang Branch of CNOOC China Co.,Ltd,Zhanjiang,Guangdong,524057,China)
出处
《天然气与石油》
2020年第3期63-67,共5页
Natural Gas and Oil
基金
中海石油(中国)有限公司综合科研项目“南海西部油田上产2000万方关键技术研究”(CNOOC-KJ 135 ZDXM 38 ZJ 01 ZJ)。
关键词
注气
井筒积液
相态恢复
露点压力
平衡油
Gas injection
Wellbore liquid accumulation
Phase recovery
Dew point pressure
Equilibrium oil
