Zhou Peng, Bao Junyao, Zhan Shiyuan, Wang Xingjian, Li Shaopeng, Lan Baofeng, Liu Zhanbo
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China.
Guizhou Energy Industry Research Institute Co., Guiyang 550025, China.
Nanomaterials (Basel). 2025 Jun 10;15(12):896. doi: 10.3390/nano15120896.
Dewatering and gas production are applied on a large scale in shale gas development. The fundamental mechanisms of water flow in shale nanoporous media are essential for the development of shale oil and gas resources. In this work, we use molecular dynamic simulations to investigate water flow in two different quartz surface ((101¯0)-α and (101¯0)-β) nanopores. Results show that the (101¯0)-β surface exhibits stronger water molecule structuring with a structure arranged in two layers and higher first-layer adsorption density (2.44 g/cm) compared to the ((101¯0)-α surface (1.68 g/cm³). The flow flux under the (101¯0)-α surface is approximately 1.2 times higher than that under the (101¯0)-β surface across various pressure gradients. We developed a theoretical model dividing the pore space into non-flowing, adsorbed, and bulk water regions, with critical thicknesses of 0.14 nm and 0.27 nm for the non-flowing region, and 0.15 nm for the adsorbed region in both surfaces. This model effectively predicts velocity distributions and volumetric flow rates with errors generally below 5%. Our findings provide insights into water transport mechanisms in shale inorganic nanopores and offer practical guidance for numerical simulation of shale gas production through dewatering operations.
在页岩气开发中，脱水和产气被大规模应用。页岩纳米多孔介质中水流的基本机制对于页岩油气资源的开发至关重要。在这项工作中，我们使用分子动力学模拟来研究两种不同石英表面（(101¯0)-α和(101¯0)-β）纳米孔中的水流。结果表明，与(101¯0)-α表面（1.68 g/cm³）相比，(101¯0)-β表面表现出更强的水分子结构化，其结构排列为两层，第一层吸附密度更高（2.44 g/cm）。在各种压力梯度下，(101¯0)-α表面下的流量通量比(101¯0)-β表面下的流量通量高约1.2倍。我们开发了一个理论模型，将孔隙空间分为非流动、吸附和体相水区域，两个表面的非流动区域临界厚度分别为0.14 nm和0.27 nm，吸附区域临界厚度为0.15 nm。该模型有效地预测了速度分布和体积流率，误差通常低于5%。我们的研究结果为页岩无机纳米孔中的水传输机制提供了见解，并为通过脱水作业进行页岩气生产的数值模拟提供了实际指导。
