摘要
为了研究裂缝对低渗透油藏CO_(2)驱油过程及驱油效果的影响,通过对天然岩心切割打磨和刻缝,制成带缝的岩心薄片,结合高清显微镜和高清录像系统,采用高温高压驱替系统开展了微观可视化实验研究。不同注入压力下的CO_(2)驱油实验结果表明:CO_(2)将优先驱替裂缝中的原油并以裂缝为主线进行渗流和扩散运移。随着压力的不断升高,CO_(2)的相态及与原油的作用发生变化,驱油效率得到一定的提高,但受裂缝的影响提高的幅度很有限。具体表现为混相驱最终驱油效率比超临界驱提高4%,超临界驱最终驱油效率比非超临界驱提高2%。吞吐实验结果表明,相比连续驱替,吞吐可以更加充分发挥CO_(2)与原油间的作用,有效地扩大波及范围和提升驱油效率,相同混相条件下驱油效率可以提高6%。实验结果表明,裂缝对CO_(2)驱油过程和驱油效果将产生重要影响。对于裂缝发育的低渗透油藏,吞吐效果明显优于驱替效果,因此探索有利的注采方式对改善开发效果具有重要的现实意义。
In order to study the influence of fractures on CO_(2) flooding process and oil flooding effect in low permeability reservoirs,core slices with fractures were made by cutting,grinding and creasing natural cores,and then microscopic visualization experiments were carried out by using high temperature and high pressure displacement system combined with high-definition microscope and high-definition video system.The experimental results of CO_(2) flooding under different injection pressures show that CO_(2) will prefertively replace the crude oil in the fracture and take the fracture as the main line for seepage and diffusion migration.With the increasing pressure,the phase state of CO_(2) and its interaction with crude oil change,and the oil flooding efficiency is improved to a certain extent,but the increase range is limited due to the influence of fractures.The specific performance is that the final oil flooding efficiency of miscible flooding is 4% higher than that of supercritical flooding,and the final oil flooding efficiency of supercritical flooding is 2% higher than that of non-supercritical flooding.Huff and puff experiment results show that compared with continuous displacement,huff and puff can give full play to the effect between CO_(2) and crude oil,effectively expand the sweep area and improve the oil flooding efficiency.Under the same miscible condition,the oil flooding efficiency can be increased by 6%.The experimental results show that fractures have an important influence on the process and effect of CO_(2) flooding.For low permeability reservoirs with developed fractures,the stimulation effect is obviously better than the displacement effect,so it is of great practical significance to explore a favorable injection-production method to improve the development effect.
作者
赵博文
ZHAO Bowen(Xi’an Shiyou University,Xi’an 710065,China)
出处
《非常规油气》
2022年第6期87-93,99,共8页
Unconventional Oil & Gas
基金
陕西省科技统筹创新工程计划项目“陕北致密砂岩油藏CO_(2)驱提高采收率关键技术研究及先导试验”(2014KTZB03-02)。
作者简介
赵博文(1996—),男,在读硕士研究生,主要从事油气田开发的研究工作。E-mail:1301876702@qq.com。
