Research Institute of Unconventional Petroleum and Renewable Energy (RIUP&RE), China University of Petroleum (East China), Qingdao 266580, Shandong, PR China.
School of Geosciences, China University of Petroleum (East China), Qingdao 266580, Shandong, PR China.
Sci Rep. 2016 Nov 29;6:37579. doi: 10.1038/srep37579.
Understanding the adsorption mechanisms of CO and N in illite, one of the main components of clay in shale, is important to improve the precision of the shale gas exploration and development. We investigated the adsorption mechanisms of CO and N in K-illite with varying pore sizes at the temperature of 333, 363 and 393 K over a broad range of pressures up to 30 MPa using the grand canonical Monte Carlo (GCMC) simulation method. The simulation system is proved to be reasonable and suitable through the discussion of the impact of cation dynamics and pore wall thickness. The simulation results of the excess adsorption amount, expressed per unit surface area of illite, is in general consistency with published experimental results. It is found that the sorption potential overlaps in micropores, leading to a decreasing excess adsorption amount with the increase of pore size at low pressure, and a reverse trend at high pressure. The excess adsorption amount increases with increasing pressure to a maximum and then decreases with further increase in the pressure, and the decreasing amount is found to increase with the increasing pore size. For pores with size greater larger than 2 nm, the overlap effect disappears.
了解 CO 和 N 在伊利石（页岩中主要的黏土成分之一）中的吸附机制，对于提高页岩气勘探和开发的精度非常重要。我们使用巨正则蒙特卡罗（GCMC）模拟方法，在 333、363 和 393 K 的温度下，在高达 30 MPa 的宽压力范围内，研究了不同孔径的 K-伊利石中 CO 和 N 的吸附机制。通过讨论阳离子动力学和孔壁厚度的影响，证明了模拟系统是合理且适用的。单位伊利石表面积的过剩吸附量的模拟结果与已发表的实验结果总体上一致。研究发现，在微孔中，吸附势能重叠，导致在低压下随着孔径的增大，过剩吸附量减少，而在高压下则相反。随着压力的增加，过剩吸附量先增加到最大值，然后随着压力的进一步增加而减少，且随着孔径的增大，减少量也增大。对于尺寸大于 2nm 的孔，重叠效应消失。
