Mechanism of enhanced oil recovery by fuzzy-ball fluid as a novel oil-displacement agent

• Published in: Energy reports Vol. 9; pp. 1447 - 1463
• Main Authors: Wang, Xiangchun, Gan, Maozong, Yang, Xumin, Zhang, Peng, Peng, Xiaojun, Ju, Yanxin, Kou, Yahao, Yu, Xing, Zheng, Lihui, Wang, Chao
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2023; Elsevier
• Subjects: Contribution ratios; Enhanced oil recovery; Fuzzy-ball fluid; Oil-washing mechanism; Fuzzy-ball fluid; Oil-washing mechanism; Enhanced oil recovery; Contribution ratios
• ISSN: 2352-4847; 2352-4847
• DOI: 10.1016/j.egyr.2022.12.072

Fuzzy-ball fluid is a two-phase fluid composed of fuzzy-ball and base fluid. It can enhance oil recovery by approximately 30% after water flooding and polymer flooding, which has been demonstrated in laboratory experiments and field applications. However, the EOR mechanism of fuzzy-ball fluid still needs further research. In this study, the microstructure of fuzzy-ball was observed using optical and cryo-scanning electron microscopy. The EOR mechanism of fuzzy-ball fluid was investigated by the microscopic glass etching model experiment and inter-molecular force calculation. EOR contribution ratio of three parts of fuzzy-ball was evaluated by the single core flooding experiment. Results showed that fuzzy-ball was further subdivided into fuzzy-ball structure and floss structure. Correspondingly, the EOR effects of fuzzy-ball fluid were mainly divided into three parts: (a) base fluid. Emulsification was the main way for base fluid to enhance oil recovery; (b) fuzzy-ball structure. According to the distribution characteristics of residual oil, the EOR mechanisms of fuzzy-ball structure were mainly as follows: wedging displacement for membranous oil, squeezing-carrying mechanism for columnar oil, and extruding-squeezing mechanism for blind-end oil; (c) floss structure. Floss structure enhanced oil recovery mainly through entanglement and carrying mechanism. Moreover, the EOR contribution ratio of base fluid, fuzzy-ball structure, and floss structure are 18.35%, 50.94%, and 30.71%, respectively. This study elucidates the EOR mechanism of fuzzy-ball fluid and provides guidance for its subsequent field application and performance improvement. [Display omitted] •Elucidated EOR mechanism of three parts of fuzzy-ball fluid, especially mechanism of floss structure to enhance oil recovery.•EOR contribution ratio of three part of fuzzy-ball fluid was quantified.•Inter-molecular force between floss structure and crude oil was calculated by inter-molecular simulation.