混相性与重力作用对CO2驱提高采收率及储存潜力的影响
Influence of miscibility and gravity on CO2 flooding for oil recovery enhancement and storage potential
陈小龙1
作者信息
- 1. 中海油研究总院有限责任公司,北京 100029
- 折叠
摘要
为了搞清楚系统混相性与重力作用对CO2驱油效率及储存潜力的影响,设计了一系列驱替实验,通过对比混相性与重力作用多种组合方式下的驱替结果,明确CO2驱提高采收率的最佳驱替方式.为了充分体现重力的作用,选择长岩心开展水平注气(重力无作用)、顶部注气(重力为驱替动力)及底部注气(重力为驱替阻力)驱油实验.结果表明:对于采收率而言,非混相时顶部注气的效果最佳,水平注气次之,底部注气最差.当压力增大至驱替系统内流体可以混相时,重力作用对CO2驱的采收率几乎没有影响.因而在进行CO2非混相驱时,在储层厚度与倾角合适的情况下,应优先考虑采用重力主导的注气方式;对于混相驱,储层厚度与注气方向不再是影响CO2驱替结果的关键因素.对于CO2埋存量而言,非混相时,充分发挥重力作用的顶部注气可以获得最高的CO2埋存量.随着压力的增大,重力作用对CO2储存量的影响减弱.混相时,无论哪种注气方向,CO2的储存潜力都非常高.研究成果为CO2驱提高采收率技术优化与矿场实践提供了依据.
Abstract
In order to understand the influence of system miscibility and gravity on CO2 displacement efficiency and storage potential,a series of displacement experiments are designed.Optimal displacement method of CO2 flooding to enhance oil recovery is determined by comparing displacement results of various combinations of miscibility and gravity.To fully reflect the effect of gravity,long core is selected for displacement experiments of horizontal gas in-jection(no gravity effect),top gas injection(gravity as displacement force)and bottom gas injection(gravity as dis-placement resistance).The results show that,for oil recovery,CO2 immiscible flooding has the best effect of top in-jection,followed by horizontal injection,and the worst of bottom injection.When the pressure is increased enough for fluid in displacement system to be miscible,gravity has almost no effect on oil recovery of CO2 flooding.There-fore,gravity-dominated gas injection should be given priority in the case of appropriate reservoir thickness and dip when CO2 immiscible flooding is carried out.For miscible flooding,reservoir thickness and gas injection direction are no longer key factors affecting the result of CO2 displacement.For CO2 storage capacity,top gas injection with full utilization of gravity in immiscible phase can achieve maximum CO2 storage capacity.The influence of gravity on CO2 storage decreases with pressure increase.In miscible phase,CO2 storage potential is very high regardless of injection direction.The research provides basis for technique optimization and field application of enhanced oil re-covery by CO2 flooding.
关键词
CO2/混相性/重力驱/采收率/CO2埋存Key words
CO2/miscibility/gravity drive/recovery/CO2 storage引用本文复制引用
出版年
2025
国家科技期刊平台
NSTL
万方数据