正十七烷在伊利石狭缝孔隙中的吸附与赋存规律研究  

Adsorption and Occurrence of n-heptadecane in Narrow Slit Pores of Illite

作　　者：马立涛 李洋冰 黄英 刘成 张群 陈韵 唐鑫 MA Litao;LI Yangbing;HUANG Ying;LIU Cheng;ZHANG Qun;CHEN Yun;TANG Xin(Engineering Technology Branch,CNOOC Energy Development Co.,Ltd.,Tianjin 300452,China;School of Civil Engineering,Chongqing Three Gorges University,Chongqing 404100,China)

机构地区：[1]中海油能源发展股份有限公司工程技术分公司,天津300452 [2]重庆三峡学院土木工程学院,重庆404100

出　　处：《西安石油大学学报（自然科学版）》2024年第6期29-38,共10页Journal of Xi’an Shiyou University（Natural Science Edition）

基　　金：中海油发展前瞻性科研项目(HFKJ-CG-GJ-2022-03)。

摘　　要：采用巨正则蒙特卡洛(GCMC)和分子动力学(MD)方法,利用Materials Studio 2020构建了4 nm、8 nm、15 nm和50 nm的伊利石狭缝孔隙模型,对研究区北部湾盆地涠西南凹陷区流二段油页岩原油主体组分正十七烷(CH 3(CH 2)15 CH 3)进行了吸附规律和扩散现象研究。研究表明,原油的吸附能力受到压力和孔径的影响较大,受温度影响相对较小。大孔径模型可以提供更多赋存空间,大量的吸附位导致大孔径模型的容纳能力强于小孔径模型的吸附能力,当狭缝孔壁吸附位被大量占据时,原油主要以游离态赋存于狭缝孔中。相同边界条件和温压条件下,绝对吸附量随着压力的增大而增加,绝对吸附量随着温度的增加呈递减趋势;烷烃在吸附和扩散运移中,分子总是向着狭缝片层方向运动,在狭缝壁面附近形成吸附层,4 nm、8 nm、15 nm和50 nm的伊利石狭缝孔中出现2个吸附层,距离孔隙中心分别约0.34 nm,3.67 nm,7.25 nm和24.21 nm处,最大吸附密度分别为0.40 g/cm 3,0.40 g/cm 3,0.28 g/cm 3和0.37 g/cm 3;烃类物质在页岩中的赋存状态主要可分为3个区,孔径小于2.3 nm的小分子吸附区,2.3~3.9 nm为强吸附区,大于3.9 nm为弱吸附区,伊利石对正十七烷的吸附行为均为物理吸附。The narrow slit pore models of illite with slit width of 4 nm,8 nm,15 nm,and 50 nm were established using grand canonical Monte Carlo(GCMC)and molecular dynamics(MD)methods and software Materials Studio 2020.The adsorption and diffusion phenomena of the main component of crude oil in the oil shale of Liu 2 member of Weixinan Depression,Beibu Bay Basin,n-Heptadecane(CH 3(CH 2)15 CH 3),were studied.The results indicate that the adsorption capacity of the illite to the crude oil is greatly influenced by pressure and pore size,and is relatively less affected by temperature.The large-size pore model can provide more storage space,and its ability to adsorb crude oil is greater than that of the small-size pore model.When a large amount of adsorption sites on the walls of narrow slit pores are occupied,crude oil mainly exists in a free state in the narrow slit pores.Under the same boundary conditions and temperature and pressure conditions,the absolute adsorption capacity increases with the increase of pressure and decreases with the increase of temperature.During the adsorption and diffusion migration of alkanes,the molecules always move in the direction of slit lamella,forming an adsorption layer near the slit wall.Two adsorption layers appeared in the illite slit pores of 4 nm,8 nm,15 nm and 50 nm,with maximum adsorption densities of 0.40 g/cm 3,0.40 g/cm 3,0.28 g/cm 3 and 0.37 g/cm 3 respectively,at distances of approximately 0.34 nm,3.67 nm,7.25 nm,and 24.21 nm from the pore center.The occurrence of hydrocarbon substances in shale can be mainly divided into three zones:the small molecule adsorption zone with pore size less than 2.3 nm,the strong adsorption zone at 2.3~3.9 nm,and the weak adsorption zone above 3.9 nm.The adsorption behavior of illite to n-heptane is physical adsorption.

关 键 词：伊利石 吸附模拟 分子扩散运动 狭缝孔 赋存状态 涠西南凹陷 

分 类 号：TE135[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]