Gong Fengming, Zhong Chuanrong, Hou Dali, Zhu Haiyan
College of Energy (College of Modern Shale Gas Industry), Chengdu University of Technology, Chengdu, Sichuan 610059, China.
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, Sichuan 610059, China.
Langmuir. 2025 Apr 15;41(14):9141-9161. doi: 10.1021/acs.langmuir.4c04376. Epub 2025 Mar 31.
The fluids within the pores of shale reservoirs are influenced by nanoscale confinement effects, causing the phase behavior and flow characteristics of the oil and gas systems to deviate from bulk properties. Consequently, conventional phase theory and experimental methodologies are inadequate for studying such confined fluids. The phase characteristics and underlying microscopic mechanisms of oil and gas within confined spaces remain unclear, posing a substantial barrier to the efficient and rational development of shale reservoirs. This paper reviews current theoretical and experimental research on fluid phase behavior under nanoscale confinement in shale reservoirs. It provides a comprehensive discussion of four categories of research techniques, including mathematical models, numerical simulations, indirect measurement experiments, and direct observation experiments, detailing their principles, primary applications, and advantages and limitations. Furthermore, it compares the relationships and differences among these techniques and offers an outlook on the future development of research into the shale fluid phase behavior. Analyses indicate that various research methods can be employed to investigate the phase behavior of fluids at the confined scale of shale reservoirs. However, due to the influence of factors such as research techniques, target materials, and experimental conditions, there is no consensus on the critical pore size responsible for confinement effects, the shift in the critical properties, and the variations in bubble and dew points. The current research adopts the research idea of "theoretical exploration through mathematical modeling, mechanism revelation via numerical simulation, regularity reflection through indirect measurement experiments, and phenomenon demonstration through direct observation experiments" and forms a relatively complete research system of the confined fluid phase behavior of shale reservoir. However, the system still has some limitations and challenges, necessitating further optimization and refinement in future research.
页岩储层孔隙内的流体受纳米尺度限域效应影响，致使油气系统的相行为和流动特性偏离其本体性质。因此，传统相理论和实验方法不足以研究此类受限流体。受限空间内油气的相特征及潜在微观机制仍不明确，这对页岩储层的高效合理开发构成了重大障碍。本文综述了页岩储层纳米尺度限域下流体相行为的当前理论和实验研究。全面讨论了四类研究技术，包括数学模型、数值模拟、间接测量实验和直接观测实验，详细阐述了它们的原理、主要应用以及优缺点。此外，比较了这些技术之间的关系和差异，并对页岩流体相行为研究的未来发展进行了展望。分析表明，可采用多种研究方法来研究页岩储层受限尺度下流体的相行为。然而，由于研究技术、目标材料和实验条件等因素的影响，对于导致限域效应的临界孔径、临界性质的变化以及泡点和露点的变化，尚无定论。当前研究采用“通过数学建模进行理论探索、借助数值模拟揭示机理、通过间接测量实验反映规律、通过直接观测实验展示现象”的研究思路，形成了相对完整的页岩储层受限流体相行为研究体系。然而，该体系仍存在一些局限性和挑战，未来研究需要进一步优化和完善。
