页岩干酪根吸附规律的分子模拟研究

doi:10.13809/j.cnki.cn32-1825/te.2022.03.007

Abstract

Abstract:

Shale gas is unconventional natural gas, mainly CH_4, occurring in organic shale. The adsorbed gas is the main source for later production of shale gas. Therefore, studying the adsorption mechanism of shale plays an important role in shale gas development. By using type Ⅱ kerogen molecules, a type Ⅱ kerogen model is established. Then, Monte Carlo method and molecular simulation method are used to study the micro adsorption behavior and mechanism of CH₄ in type Ⅱ kerogen. Experimental data are used to verify this model, and the effects of pore size, temperature and pressure on the adsorption behavior are investigated. The findings are as follows: ① The higher the pore size, the greater the excess adsorption capacity of CH₄. The higher the temperature, the lower the excess adsorption capacity of CH₄. With the increase of pressure, the absolute adsorption amount of CH₄ increases rapidly at first and then gently, and the excess adsorption amount of CH₄ increases first and then decreases. ② The adsorption heat of CH₄ decreases with the increase of pore size. The adsorption of CH₄ in kerogen is physical adsorption. ③ When the pore size is smaller than 1 nm, CH₄ is the adsorption phase in kerogen; when the pore size is larger than one nanometer（1 nm）, CH₄ is the coexistence of adsorption phase and free phase in kerogen.

Key words: molecular simulation, shale gas, kerogen, adsorption, adsorption mechanism

CLC Number:

TE377

Jinghui LI,Xin HAN,Sijing HUANG, et al. Molecular simulation of adsorption law for shale kerogen[J]. Petroleum Reservoir Evaluation and Development, 2022, 12(3): 455-461.

Figures/Tables 13

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References 24

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结构参数	数值
H/C	1.170
O/C	0.095
N/C	0.024
S/C	0.012
芳香度	0.410
羰基中的氧原子个数	7
羧基中的氧原子个数	4
醚基中的氧原子个数	13

	原子类型	势井深度（kcal/mol）	作用势为0时原子间的距离（nm）	原子电荷（e）
甲烷	CH₄	15.941	0.330	0.890
	C	3.016	0.424	0.651
	H	0	0	0.424
干酪根	O	0.957	0.341	-0.445
	N	0.774	0.366	0
	S	3.440	0.403	0

Molecular simulation of adsorption law for shale kerogen

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