不同润湿性修饰石英吸附甲烷的模拟研究

Simulation of Methane Adsorption of Quartz with Different Wettability

润湿性是油气藏储层岩石的重要基础参数之一,其特征直接影响流体在岩石孔道内的微观分布和宏观分布特征。从微观层面认识页岩气与矿物的相互作用是深入理解页岩气赋存状态的基础。采用分子模拟研究了甲烷在不同石英模型中的吸附行为,考察了不同晶面、亲水与亲油官能团修饰模型对甲烷吸附的影响。研究结论表明,不同晶面模型中,(100)面的吸附量大于其他晶面的吸附量;甲烷在亲油修饰模型中的吸附量大于亲水修饰模型的吸附量;两种修饰模型吸附量均随着压力增加而增加,随温度的升高而减小,且温度对吸附量的影响小于孔径的影响;相同条件下,润湿性修饰模型的吸附量远大于无润湿性修饰模型的吸附量;1 nm修饰模型中甲烷只在壁面处形成吸附层,而2 nm修饰模型中形成多个吸附层。

As one of the important basic parameters of reservoir rocks,wettability′s characteristics directly affect the micro and macro distribution characteristics of fluids in rock pores.Understanding the interaction between shale gas and minerals at the micro-level is the basis of understanding the state occurrence of shale gas.Molecular simulation was used to study the adsorption of methane in different conditions of modified quartz,and different crystal faces and wettability were studied.The conclusions of the study are as follows.In different crystal-faces models,the adsorption capacity of(100)surface is greater than that of the other models.The adsorption of methane in the modified oil-philic model is larger than that in the modified water-philic model.The adsorption of methane in different wettability modification models increases with the increase of pressure,and decreases with the increase of temperature,and the effect of temperature is less than that of aperture.Under the same conditions,the adsorption capacities of the modified models are much larger than that of the unmodified model.In the 1 nm modified models,an adsorption layer is formed at the wall surface,while multiple adsorption layers are formed in 2 nm modified models.