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日用化学工业(中英文) ›› 2023, Vol. 53 ›› Issue (6): 617-624.doi: 10.3969/j.issn.2097-2806.2023.06.002

• 基础研究 • 上一篇    下一篇

CO2对长庆采出油水物性影响及乳状液稳定机理

王华正1,2,张亮1,2,*(),康鑫3,康万利1,2,李哲1,2,杨红斌1,2   

  1. 1.中国石油大学(华东) 非常规油气开发教育部重点实验室,山东 青岛 266580
    2.中国石油大学(华东) 石油工程学院,山东 青岛 266580
    3.大庆油田勘探开发研究院成都分院,四川 成都 610000
  • 收稿日期:2022-09-27 修回日期:2023-05-29 出版日期:2023-06-22 发布日期:2023-06-25
  • 基金资助:
    国家自然科学基金重点项目(52130401)

Effect of CO2 on physical properties of produced oil and water in Changqing and emulsion stabilization mechanism

Wang Huazheng1,2,Zhang Liang1,2,*(),Kang Xin3,Kang Wanli1,2,Li Zhe1,2,Yang Hongbin1,2   

  1. 1. Key Laboratory of Unconventional Oil & Gas Development (China University of Petroleum (East China)), Ministry of Education, Qingdao, Shandong 266580, China
    2. School of Petroleum Engineering in China University of Petroleum (East China), Qingdao, Shandong 266580, China
    3. Chengdu Branch of Daqing Oilfield Exploration and Development Research Institute, Chengdu, Sichuan 610000, China
  • Received:2022-09-27 Revised:2023-05-29 Online:2023-06-22 Published:2023-06-25
  • Contact: *E-mail: zhangliangkb@163.com.

摘要:

二氧化碳(CO2)驱作为一项日益完善的采油技术,已经成为提高低渗油田采收率的重要手段,具有适用范围广、开采成本低和洗油效率高等优点。然而,由于CO2特殊的物理和化学性质,其采出液稳定性较常规水驱明显增强,为采出液处理带来了困难。通过光学显微镜、动态光散射、流变学等方法,研究了在不同压力下CO2处理对长庆原油和采出水的物性以及所形成的油包水(W/O)型乳状液稳定性的影响,探究了CO2驱采出液乳化和稳定的影响因素。结果表明,随着CO2压力的增大,CO2驱采出水中Ca2+和Mg2+质量浓度均有所下降,而CO32-与HCO3-总体含量有所增加,水相pH值略下降,从弱碱性转变为弱酸性。CO2处理导致原油中轻质组分减少,胶质沥青质等重质组分的含量升高,原油极性增强。CO2处理后油的反常温度和析蜡点均升高,原油黏度增加。CO2处理后W/O型乳状液的液滴粒径变小,均一性增强,粒径由2.14 μm减小至0.61 μm。由于乳状液体系黏度上升以及胶质、沥青质和水中颗粒在油/水界面膜上吸附成膜,从而提高油/水界面膜强度,使得乳状液的稳定性增强。为CO2驱采出液处理工艺提供理论指导和技术支撑。

关键词: CO2驱, 乳状液, 稳定性, 原油物性, 流变性

Abstract:

Carbon dioxide (CO2) flooding has become an important means to improve the recovery efficiency of low-permeability oil fields, with the advantages including wide range of application, low production cost and high oil-washing efficiency. However, due to the special physical and chemical properties of CO2, the stability of corresponding produced liquid is significantly enhanced compared with that of conventional water flooding, which brings many difficulties to the treatment of produced liquid. By means of optical microscope, dynamic light scattering, rheology and other methods, the effects of CO2 treatment on the physical properties of Changqing crude oil and produced water under different pressures and the stability of the water-in-oil (W/O) emulsion were studied, and the factors affecting the emulsification and stability of the produced liquid from CO2 flooding were studied. The results showed that, with the increase of CO2 pressure, the mass concentrations of Ca2+and Mg2+ ions in produced water for CO2 flooding were decreased, while the overall content of CO32- and HCO3- ions was increased, and the pH value of the water phase was slightly decreased, changing from weak alkalinity to weak acidity. CO2 treatment led to the decrease of light components and the increase of heavy components (such as resins and asphaltenes) in crude oil, and the enhancement of crude oil polarity. The abnormal temperature and wax precipitation point of the crude oil after CO2 treatment were both increased, and the viscosity of the crude oil was increased. After CO2 treatment, the droplet size of W/O emulsion became smaller, and its homogeneity was enhanced. The particle size changed from 2.14 μm to 0.61 μm. As the viscosity of the emulsion was increased and the resins, asphaltenes and the particles in water adsorbed on the oil-water interface to form a film, the strength of the interfacial film was improved and the stability of the emulsion was thus enhanced. The clarification of emulsion stabilization mechanism could provide theoretical guidance and technical support for treatment process to the produced liquid from CO2 flooding.

Key words: CO2 flooding, emulsion, stability, physical properties of crude oil, rheology

中图分类号: 

  • O648.23