Mathematical Simulation of Coal-generating Hydrocarbons Based on Pyrolysis Products from Coal Macerals under Closed System
Received date: 2008-09-09
Revised date: 2009-01-19
Online published: 2009-02-10
Based on the hydrocarbon yields and carbon isotopes of methane from the three end-member macerals (vitrinite, exinite, inertinite) under closed system pyrolysis, isothermal temperature conditions, a mathematic model of oil generation and efficient expulsion from coal as a hydrocarbon-sourcing rock was done when the efficient expulsion of hydrocarbons from coal is experientially assumed to be 30 mg/gTOC.According to the simulated results, the hydrogen enriched maceral is prone to the oil generation, where the relative proportion of exinite component in coal as an active oil source is at least 5.0% whereas vitrinite is at most 95.0%. If the exinite content is more than 22.9% of coal components, the oil is generated and efficiently expelled from coal whatever the contents of two other macerals (vitrinite and inertinite). Meanwhile, the carbon isotope fractionation of methane from the maceral components at thermal stages was matched according to the simulated model. These mathematically calculated observations imply that coals with the different end\|member macerals would generate natural gas with changed δ13CCH4 values, where the maximum δ13CCH4 value is 2.3‰. Thus, the δ13CCH4 value is constrained by not only thermal maturity of source rock, but also maceral components.
Key words： Macerals; Hydrocarbon yield; Carbon isotope; Mathematic model.
LIU Quan-You, LIU Wen-Hui, WANG Chang-Hua . Mathematical Simulation of Coal-generating Hydrocarbons Based on Pyrolysis Products from Coal Macerals under Closed System[J]. Natural Gas Geoscience, 2009 , 20(1) : 20 -25 . DOI: 10.11764/j.issn.1672-1926.2009.01.20
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