Enhanced mass transfer between matrix and filled fracture in dual-porosity media during spontaneous imbibition based on low-field nuclear magnetic resonance
Enhanced mass transfer between matrix and filled fracture in dual-porosity media during spontaneous imbibition based on low-field nuclear magnetic resonance
复制标题
基于低场核磁共振的自发渗吸过程中双孔隙介质基质与充填裂缝之间的强化传质
DOI：
10.1016/j.jhydrol.2022.127521
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发表时间：
2022-02-01
影响因子：
6.4
通讯作者：
Zhou, Zhifang
中科院分区：
文献类型：
--
作者：
Dou, Zhi;Zhao, Yan;Zhou, Zhifang
润湿性流体的自发自吸（SI）是许多水文和地质应用的重要过程。在这项研究中，我们研究了实验和理论的SI过程中的双孔隙介质组成的基质和填充裂缝。利用低场核磁共振（LF NMR）技术，动态监测了SI实验过程中双孔隙介质中吸入水的分布。基于低频核磁共振理论，提出了一种定量区分基质和充填裂缝中的吸入水的截止值方法。结果表明，双孔隙介质中基质自吸速率大于单孔隙介质。单孔隙介质和双孔隙介质之间基质自吸速率的不一致是由基质和填充裂缝之间的增强的质量传递引起的。然后提出了一个分析模型来表征这种增强的基质和填充裂缝之间的传质。结果表明，基质的自吸速率不仅与裂隙的存在有关，而且与裂隙中填充颗粒的大小有关。一个明确的非单调关系被发现之间的基质吸胀率和填充在裂缝中的颗粒的大小。随着填充在裂缝中的颗粒尺寸的增加，基质自吸的速率先增加后减小。该分析模型不仅突出了基质和填充裂缝之间的传质增强机制，而且还能够确定裂缝中填充颗粒的最佳等效毛细管直径，以提高双重孔隙介质中基质的自吸速率。
Spontaneous imbibition (SI) of wetting fluids is an important process for many hydrological and geological applications. In this study, we investigated experimentally and theoretically the SI process in a dual-porosity medium consisting of the matrix and the filled fracture. Low-field nuclear magnetic resonance (LF NMR) technology was used to dynamically monitor the distribution of the imbibed water in the dual-porosity media during the SI experiments. Based on the LF NMR theory, a cut-off method was proposed to quantitatively distinguish the imbibed water from the matrix and the filled fracture. The results showed that the rate of matrix imbibition was greater in the dual-porosity media than in single-porosity media. This inconsistent rate of matrix imbibition between the single-porosity media and the dual-porosity media was caused by the enhanced mass transfer between the matrix and the filled fracture. An analytical model was then proposed to characterize this enhanced mass transfer between the matrix and the filled fracture. It was found that the rate of matrix imbibition was not only affected by the presence of the filled fractures but also depended on the size of the particles filled in the fracture. A clear non-monotonic relationship was found between the rate of matrix imbibition and the size of the particles filled in the fracture. The rate of matrix imbibition initially increased and then decreased as the size of the particles filled in the fracture increased. The proposed analytical model not only highlighted the mechanism of enhanced mass transfer between the matrix and the filled fracture, but was also able to determine the optimum equivalent capillary diameter of the filled particles in the fracture for enhanced rate of matrix imbibition in dualporosity media.