石油与天然气地质 ›› 2019, Vol. 40 ›› Issue (6): 1333-1338.doi: 10.11743/ogg20190617

• 方法技术 • 上一篇    下一篇

页岩油注CO2动用机理

赵清民1,2,3, 伦增珉1,2,3, 章晓庆4, 郎东江1,2,3, 王海涛1,2,3   

  1. 1. 国家能源页岩油研发中心, 北京 100083;
    2. 页岩油气富集机理与有效开发国家重点实验室, 北京 100083;
    3. 中国石化 石油勘探开发研究院, 北京 100083;
    4. 中国石油 大港油田分公司, 天津 300280
  • 收稿日期:2019-02-18 修回日期:2019-05-13 出版日期:2019-12-28 发布日期:2019-10-15
  • 作者简介:赵清民(1986-),男,高级工程师,致密/页岩油气渗流理论及提高采收率技术。E-mail:zhaoqm2013@163.com。
  • 基金资助:
    国家科技重大专项(2017ZX05049003)。

Mechanism of shale oil mobilization under CO2 injection

Zhao Qingmin1,2,3, Lun Zengmin1,2,3, Zhang Xiaoqing4, Lang Dongjiang1,2,3, Wang Haitao1,2,3   

  1. 1. State Energy Center for Shale Oil Research and Development, Beijing 100083, China;
    2. State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China;
    3. Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China;
    4. Dagang Oilfield Company, PetroChina, Tianjin 300280, China
  • Received:2019-02-18 Revised:2019-05-13 Online:2019-12-28 Published:2019-10-15

摘要: CO2由于良好的注入性及与原油的混相能力,可能是页岩油藏提高采收率最有效的方法。与常规油藏不同,页岩储层裂缝及微纳米孔隙发育,CO2能否进入页岩微纳米孔隙并动用孔隙中的原油是利用CO2提高页岩油采收率的关键。因此,设计开展了页岩油注CO2实验,基于核磁共振方法研究了页岩微纳米孔隙中原油动用特征及动用机理,并研究了接触时间及接触次数对采出程度的影响。核磁共振T2谱及核磁成像结果表明注CO2可以有效动用页岩微纳孔隙中的原油,一次接触实验采收率为32.63%。随着CO2与原油接触时间增加,在初始阶段采油速度高,然后采油速度逐渐变缓。CO2溶解扩散作用是动用页岩微纳孔隙原油的主控机理。研究成果证实注CO2可以有效提高页岩油藏采收率,为陆相页岩油有效开发提供参考。

关键词: 微纳米孔隙, 裂缝, 核磁共振, 扩散, CO2, 页岩油, 提高采收率

Abstract: CO2 injection may be the most effective method to enhance shale oil recovery due to its good injectivity and miscibility with crude oil.However,unlike conventional reservoirs,shale reservoirs usually feature fractures and micro/nano-scale pores,and thus whether CO2 can enter micro/nano-scale pores to mobilize oil inside is the key to a successful CO2-EOR in shale reservoirs.Therefore,a CO2-EOR experiment was carried out to find out the features and mechanism of oil mobilization in the micro/nano-scale pores of shales by means of nuclear magnetic resonance (NMR).In addition,effects of total exposure time and times of exposure on recovery performance were also investigated.Both NMR T2 spectrum and images indicate that oil in all shale pores can be effectively mobilized by CO2 injection.The recovery factor is 32.63% for the first shale oil -CO2 contact.The production rate is correlated to the exposure time:an initial fast-increa-sing stage followed by a declining stage hereafter.The CO2 diffusion is the main mechanism driving the CO2-EOR in shale reservoirs.In conclusion,the study has proven that CO2 injection serves to effectively enhance shale oil recovery,which may provide an analogy to the effective development of continental shale oil elsewhere.

Key words: micro/nano-scale pore, fracture, nuclear magnetic resonance (NMR), diffusion, CO2, shale oil, enhanced oil recovery (EOR)

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