Zhou Wenning, Zhang Zhe, Wang Haobo, Yan Yuying, Liu Xunliang
School of Energy and Environmental Engineering, University of Science and Technology Beijing Beijing 100083 China
Beijing Key Laboratory of Energy Saving and Emission Reduction for Metallurgical Industry, University of Science and Technology Beijing Beijing 100083 China.
RSC Adv. 2018 Oct 3;8(59):33939-33946. doi: 10.1039/c8ra07486k. eCollection 2018 Sep 28.
In the present study, competitive adsorption behaviour of supercritical carbon dioxide and methane binary mixture in shale organic nanopores was investigated by using grand canonical Monte Carlo (GCMC) simulations. The model was firstly validated by comparing with experimental data and a satisfactory agreement was obtained. Then the effects of temperature (298-388 K), pressure (up to 60 MPa), pore size (1-4 nm) and moisture content (0-2.4 wt%) on competitive adsorption behaviour of the binary mixture were examined and discussed in depth. It is found that the adsorption capacity of carbon dioxide in shale organic nanopores is much higher than that of methane under various conditions. The mechanism of competitive adsorption was discussed in detail. In addition, the results show that a lower temperature is favorable to both the adsorption amount and selectivity of CO/CH binary mixture in shale organic nanopores. However, an appropriate CO injection pressure should be considered to take into account the CO sequestration amount and the exploitation efficiency of shale gas. As for moisture content, different influences on CO/CH adsorption selectivity have been observed at low and high moisture conditions. Therefore, different simulation technologies for shale gas production and CO sequestration should be applied depending on the actual moisture conditions of the shale reservoirs. It is expected that the findings in this work could be helpful to estimate and enhance shale gas resource recovery and also evaluate CO sequestration efficiency in shale reservoirs.
在本研究中，通过巨正则蒙特卡罗（GCMC）模拟研究了超临界二氧化碳和甲烷二元混合物在页岩有机纳米孔隙中的竞争吸附行为。首先通过与实验数据对比对模型进行了验证，并获得了满意的一致性。然后深入考察并讨论了温度（298 - 388 K）、压力（高达60 MPa）、孔径（1 - 4 nm）和含水量（0 - 2.4 wt%）对二元混合物竞争吸附行为的影响。发现在各种条件下，页岩有机纳米孔隙中二氧化碳的吸附容量远高于甲烷。详细讨论了竞争吸附的机理。此外，结果表明较低的温度有利于页岩有机纳米孔隙中CO/CH二元混合物的吸附量和选择性。然而，应考虑适当的CO注入压力，以兼顾CO封存量和页岩气开采效率。至于含水量，在低含水量和高含水量条件下观察到对CO/CH吸附选择性有不同影响。因此，应根据页岩储层的实际含水量条件应用不同的页岩气生产和CO封存模拟技术。预计本工作的研究结果有助于估算和提高页岩气资源采收率，也有助于评估页岩储层中的CO封存效率。
