页岩不同类型干酪根内甲烷吸附行为的分子模拟

发布时间：2018-03-24 23:02

本文选题：页岩　切入点：干酪根　出处：《天然气工业》2017年12期

【摘要】：目前对于页岩中不同类型有机质干酪根对甲烷的吸附影响规律尚不清楚。为此,根据页岩干酪根的元素含量、分子结构构建了腐泥型、混合型和腐殖型的干酪根分子模型,利用巨正则蒙特卡罗方法和分子动力学模拟方法研究甲烷在干酪根中的吸附行为,并进行了实验验证。进而探讨了温度、地温梯度、干酪根分子组成、比表面积对甲烷—干酪根吸附系统的影响,以及甲烷在页岩干酪根内的微观吸附机理。结果表明:(1)腐殖型干酪根对甲烷的吸附量最大,混合型次之,腐泥型最小;(2)干酪根的化学结构对甲烷的吸附有着重要的影响,富含芳香族的干酪根对甲烷具有更强的亲和力,碳、硫原子对甲烷在干酪根中吸附的影响较大;(3)甲烷在干酪根中吸附属于物理吸附,温度越高甲烷吸附量越小,平均等量吸附热均小于42 k J/mol;(4)随着地层深度的增加,甲烷吸附量先增加后减少,在地层深度介于2 000~2 500 m甲烷绝对吸附量达到峰值,地温梯度越小相同埋深下甲烷吸附量越多;(5)甲烷吸附量与干酪根的比表面积呈线性正相关关系。
[Abstract]:At present, the effect of different organic matter kerogen on methane adsorption in shale is not clear. Therefore, according to the element content of shale kerogen, molecular structure of humic, mixed and humic kerogen molecular models are constructed. The adsorption behavior of methane in kerogen was studied by means of grand regular Monte Carlo method and molecular dynamics simulation. The temperature, geothermal gradient and molecular composition of kerogen were discussed. The effect of specific surface area on the adsorption system of methane and kerogen, as well as the microscopic adsorption mechanism of methane in shale kerogen. The results show that the adsorption amount of methane on humic kerogen is the largest, followed by mixed type. The chemical structure of kerogen has an important influence on the adsorption of methane. The rich aromatic kerogen has stronger affinity to methane, carbon, The adsorption of methane in kerogen belongs to physical adsorption. The higher the temperature, the smaller the amount of methane adsorption. The average adsorption heat of methane is less than 42 k / mol ~ (4)) with the increase of formation depth. The adsorption capacity of methane increased first and then decreased. The absolute adsorption capacity of methane reached a peak value at a depth of 2 000 ~ 2 500 m, and the adsorption capacity of methane increased at the same buried depth with a lower geothermal gradient.) the adsorption capacity of methane was positively correlated with the specific surface area of kerogen.
【作者单位】： "油气资源与工程"国家重点实验室·中国石油大学(北京);
【基金】：国家自然科学基金重大项目“多重耦合下的页岩油气安全优质钻井理论”(编号:51490652)
【分类号】：P618.13

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