Abstract: Shale reservoirs are characterized by their nanometer pore size. At the nanoscale, fluid flow mechanisms and phase behaviors are significantly influenced by the size and surface effects, resulting in deviations from classical fluid theories. Conventional oil and gas reservoir engineering theory is not fully applicable to shale reservoirs, restricting the efficient development of shale oil and gas. It is thus of both scientific significance and engineering value to clarify fluid transport and phase properties at the nanometer pore scale of shale. Nanofluidics, with the capabilities of precisely manufacturing pore structure and observing in-situ fluid behaviors at the nanoscale, gives new experimental insights into microscopic seepage and phase behavior of shale oil and gas, and provides essential validation for theoretical studies. This paper reviews recent research progress on the nanofluidic study of the nanoscale single- and two-phase flow of oil, gas and water, phase behavior of single- and multi-component hydrocarbons, diffusion and mixing process, as well as microphysical model of shale reservoirs. We focus on introducing nanofluidic methods to detect fluid characteristics, and the differences between experimental results and theoretical descriptions. The current limitations of nanofluidic studies of shale reservoir fluids are discussed in the end, and future directions in this field are foreseen.

Key words: shale reservoir, nanofluidic chip, microscopic flow mechanism, fluid phase characteristics, microphysical model

摘要： 页岩储层的孔隙尺寸主体是纳米级，在纳米尺度下流体的流动机理和相态特征受到尺度效应和壁面效应的显著影响而偏离经典理论描述，致使常规油气藏中的流体特征认知不完全适用于页岩油气藏，从根源上制约着页岩油气的高效开发。因此，明确页岩储层在纳米孔隙尺度下的微观流体特征具有显著的科学意义和工程价值。纳米流控技术具备纳米级孔隙精准制备和原位可视化检测的特点，为页岩油气微观渗流与相态特征的研究提供了全新的实验视角，也为纳米尺度下流体特征的理论研究提供了实验依据。对纳米流控实验技术进行了介绍，并回顾了基于该技术在纳米尺度下油气水的单相及两相流动规律、单组分烃及多组分烃相态特征、扩散与混相过程，以及页岩储层微观物理模型的最新研究进展，重点梳理了页岩储层微观流体特征的纳米流控实验研究方法、实验结果以及与理论研究间的对照情况。同时指出了当前纳米流控技术在研究页岩储层微观流体特征中存在的不足，展望了今后的发展方向。

关键词: 页岩油气藏, 纳米流控芯片, 微观流动机理, 流体相态特征, 微观物理模型