天然气工业2017，Vol.37Issue(12)：18-25,8.DOI:10.3787/j.issn.1000-0976.2017.12.003
页岩不同类型干酪根内甲烷吸附行为的分子模拟
Molecular simulation of methane adsorption behavior in different shale kerogen types
摘要
Abstract
The impact of different kerogen types on the methane adsorption behavior is still not clear at present.In view of this,a model was built according to the molecular structures of three kirogen types:Type Ⅰ-Sapropel,Type Ⅱ-Sapropel-Humic,and Type Ⅲ-Humic,in which the adsorption behaviors of methane were investigated by using the Grand Canonical Monte Carlo (GCMC) and Molecular Dynamic (MD) methods,and this model and results were validated.On this basis,the effects were also discussed of temperature,geothermal gradient,and the molecular composition and the specific surface area of kerogen on the adsorption of a methane-kerogen adsorption system,and the micro scopic adsorption mechanism of methane in kerogen was revealed.The following results were obtained.(1) The adsorbed methane amount in Type Ⅲ kerogen was the largest,followed by TypeⅡ,and Type Ⅰ the smallest.(2) The chemical structure of kerogen significantly influences its adsorption amount of methane:the kerogen with more aromatic hydrocarbons and cyclanes have a stronger affinity for methane,and the carbon and sulfur atoms play an important role in the adsoprtion of kerogen to methane.(3) As temperature increases,the average isosteric adsorption heat of methane decreases,and it is always less than 42 kJ/mol,indicating that this adsorption is a physical adsorption.(4) As the depth of stratum increases,the adsorption amount first increases and then decreases,reaching the maximum at 2 000 2 500 meters.At the same depth,the smaller the geothermal gradient,the more the methane adsorption amount.(5) The adsorption amount of methane has a linear relationship with the specific surface area of kerogen.关键词
页岩/干酪根/甲烷/吸附行为/地温梯度/比表面积/分子模拟Key words
Shale/Kerogen/Methane/Adsorption mechanism/Geothermal gradient/Specific surface area/Molecular simulation引用本文复制引用
田守嶒,王天宇,李根生,盛茂,任文希..页岩不同类型干酪根内甲烷吸附行为的分子模拟[J].天然气工业,2017,37(12):18-25,8.基金项目
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). （编号:51490652）
