页岩表面甲烷气吸附机理及影响因素研究

发布时间：2018-03-05 08:28

本文选题：页岩气　切入点：吸附　出处：《石油钻探技术》2017年02期 　论文类型：期刊论文

【摘要】：页岩表面甲烷气的吸附机理及影响因素研究对于准确预测页岩气藏的可采储量至关重要,为此利用MS软件,采用巨正则蒙特卡罗方法建立了页岩气在泥页岩地层中的吸附模型,对页岩气在地层中的存在状态进行了分子动力学模拟。分别用石墨代替有机质干酪根、二氧化硅晶体代替黏土矿物、甲烷气(CH_4)代替页岩气,模拟了不同大小孔隙石墨和不同极性二氧化硅表面CH_4的吸附过程,分析了吸附状态、吸附能等参数。分子模拟结果表明,CH_4与二氧化硅表面的作用以库仑力为主,吸附能和吸附量随表面极性增强而降低;CH_4与石墨表面的作用以范德华力为主,吸附体系总能量和吸附能均随孔隙直径增大而降低,因此CH_4的吸附厚度和吸附态CH_4的比例也随之减小。研究表明,有机质是CH_4吸附的主要载体,石墨对CH_4的吸附能力远大于二氧化硅,且CH_4在石墨表面的吸附为多层的物理吸附,是影响页岩储层CH_4储量的主要因素。
[Abstract]:The study of adsorption mechanism and influencing factors of methane gas on shale surface is very important to predict the recoverable reserves of shale gas reservoir accurately. In this paper, the adsorption model of shale gas in shale formation is established by using the software MS and the giant regular Monte Carlo method. In this paper, the molecular dynamics simulation of shale gas in the formation has been carried out, which uses graphite instead of organic matter kerogen, silica crystal instead of clay mineral, methane gas CH4) instead of shale gas, respectively. The adsorption process of CH_4 on the surface of porous graphite and silicon dioxide with different sizes and polarity was simulated, and the adsorption state and adsorption energy were analyzed. The adsorption energy and adsorption amount decrease with the increase of surface polarity. The interaction between CH4 and graphite surface is dominated by van der Waals force. The total energy and adsorption energy of adsorption system decrease with the increase of pore diameter. Therefore, the adsorption thickness of CH_4 and the proportion of adsorbed CH_4 also decreased. The results show that organic matter is the main carrier of CH_4 adsorption, the adsorption ability of graphite to CH_4 is much larger than that of silica, and the adsorption of CH_4 on graphite surface is multilayer physical adsorption. It is the main factor that affects the CH_4 reserves of shale reservoir.
【作者单位】：中石化胜利石油工程有限公司黄河钻井总公司;
【分类号】：P618.13

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