Microscale dynamics of spontaneous imbibition and its quantification in the two-phase Darcy model
自发渗吸微观动力学特性及其在两相达西模型中的量化

PI: Chao-Zhong Qin
Funding: National Natural Science Foundation of China (中国自然科学基金委)
Period: 2021.01 - 2024.12

摘要
自发渗吸是很多工业应用和地下能源开采的重要机制，定量的微观与宏观模型对于揭示复 杂渗吸机理和提供可靠工程预测至关重要，但目前这方面的研究还比较欠缺。本项目拟发展高 效定量的动态孔隙网络模型，研究正向自发渗吸的微观动力学特性，并实现其在两相达西模型 中的量化。主要研究内容包括：利用医学CT获得岩心正向自发渗吸基准实验数据；修正并完善 自研的自发渗吸动态孔隙网络模型，对比基准实验实现模型的量化；开展全岩心的自发渗吸微 观数值模拟，研究不同渗吸工况下微观动力学特性及其对渗吸速率、非润湿相残余及分布、渗 吸前缘粗糙度演化的影响和控制机制；研究微观动力学特性对宏观毛细管力和相渗曲线的影响 ；利用润湿相饱和度随时间的变化率表征微观动力学特性，并将其引入宏观毛细管力和相渗曲 线中，以实现定量的自发渗吸两相达西模型。项目成果有助于进一步提高对自发渗吸机理的认 识，为实际应用提供理论依据和定量化的数值研究工具。

Spontaneous imbibition (SI) is a key mechanism in many industrial applications and subsurface energy exploitation. Quantitative microscale and macroscale SI models are crucial to unveil complex imbibition mechanisms and to provide reliable engineering predictions. Up to now, however, relevant studies are still insufficient. In this project, we will develop an efficient and quantitative dynamic pore-network model for SI. We will investigate microscale dynamics of cocurrent SI, and quantify it in the two-phase Darcy model. The main research contents include: establish benchmark data of cocurrent SI in core samples by clinical CT; improve the in-house dynamic pore-network model, and validate it against the benchmark data; conduct full-core pore-scale numerical simulations of SI, investigate the effect of microscale dynamics on SI rates, nonwetting-phase residual and its distributions, and roughening evolutions of the SI front; investigate the effect of microscale dynamics on macroscale capillary pressure and relative permeability curves; use the rate of wetting-phase saturation to represent microscale dynamics at the REV scale, then introduce it into macroscale capillary pressure and relative permeability, ultimately develop quantitative two-phase Darcy model for cocurrent SI. Project achievements will help us further understand SI mechanisms, and provide theoretical basis and quantitative numerical tools to practical applications.