基于气驱提高页岩原油采收率技术分析

Technical Analysis of Increasing Shale Crude Oil Recovery Based on Gas Drive

页岩油藏的低采收率和巨大的页岩油储量激发了我们努力研究增强油采方法在页岩油藏中的应用。最近的数值研究表明,循环注气可以是提高页岩油储层采收率的有效方法,可以缓解气窜现象。本文介绍了我们的实验验证和量化方法,以通过页岩油藏中的循环注气提高采收率。使用了Barnett,Marcos和Eagle Ford页岩的岩心塞。所使用的油是矿物油(Soltrol 130),采用氮气作为驱气。实验中使用未破裂的岩心。研究了循环时间和注入压力对油采收率的影响,以及其他参数。我们的结果还表明,取决于注入压力和页岩岩心类型,循环气注入可将采收率从10%提高到50%。这项研究表明,循环气体注入的重要机制之一是在生产阶段引起大压降的压力效应。循环注气为改善页岩储层中的油采收率提供了有效而实用的方法,因为所需的气体可在富含液体的页岩层中获得。

The low recovery rate and huge shale oil reserves of shale oil reservoir inspire us to study the application of enhanced oil recovery method in shale oil reservoir.Recent numerical studies show that cyclic gas injection can be an effective method to improve the recovery of shale oil reservoir and alleviate gas channeling.This paper intro⁃duces our experimental verification and quantitative method to improve oil recovery by cyclic gas injection in shale reservoir.Core plugs from Barnett,Marcos and Eagle Ford shale were used.The oil used is mineral oil(soltrol 130)and nitrogen is used as the purging gas.An unbroken cores were used in the experiment.The effects of cycle time and injection pressure on oil recovery and other parameters are studied.Our results also show that depending on the injection pressure and shale core type,the recovery can be increased from 10%to 50%by cyclic gas injec⁃tion.This study shows that one of the important mechanisms of cyclic gas injection is the pressure effect of large pressure drop in the production stage.Cyclic gas injection provides an effective and practical method to improve oil recovery in shale reservoir,because the required gas can be obtained in the fluid rich shale.