【作者】 陈润；

【导师】 苏现波； 李凯琦；

【作者基本信息】 河南理工大学 ， 矿产普查与勘探， 2007， 硕士

【摘要】 煤层气分馏机理的探讨,在使煤层气分馏地质效应得以解释的同时,也为煤层气富集成藏研究提供支撑。本文应用吸附势理论、从头计算理论、亨利定律及其相关理论等对煤层气分馏效应进行了系统研究,发现煤层气的分馏存在四种机理:解吸—扩散—运移分馏、溶解—运移分馏、微生物分馏和高温裂解分馏。（1）吸附势理论的引入,使得煤层气解吸-扩散-运移分馏机理得以合理解释。13CH₄因其吸附势普遍高于12CH₄而具有优先吸附、滞后解吸的特征,12CH₄更容易发生运移分馏。二氧化碳与甲烷相比,具有优先吸附、滞后解吸的特征,甲烷具有强的分馏效应,特别是在高压下。指出高压下更有利于注入二氧化碳强化甲烷产出工艺的实施。从头计算理论的引入,计算了煤与不同气体及水分子之间的作用力,从量子角度解释了煤层气吸附/解吸—扩散分馏效应。（2）地下水的溶解作用使得CO₂被优先溶解并被运移至滞留区聚集,导致滞留区CO₂的含量高;CH₄碳同位素具有相同的分馏效应,即13CH₄在滞留区的含量比径流区高。（3）微生物甲烷以CH₃COOH发酵和CO₂还原两种途径产生,且以C_O2还原为主,两种微生物成因的甲烷都造成甲烷碳同位素变轻。（4）高温裂解作用的存在造成煤层甲烷碳同位素变重。更多还原

【Abstract】 The investigation on coalbed gas fractionation can not only explain the geological effect of coalbed gas fractionation, but also offer theory support for the prediction of coalbed gas accumulation. Based on adsorption potential theory, ab initio calculation theory, Henry Law, and other relational theories, coalbed gas fractionation mechanisms were systemically discussed. There have four kinds of coalbed gas fractionation mechanism: desorption-diffusion-migration fractionation, solution-migration fractionation, microorganism fractionation, and high temperature cracking fractionation, which are described as follow: （1） the mechanism of coalbed gas desorption-diffusion-migration fractionation can be interpreted by adsorption potential theory. The coal is preferential adsorption of 13CH4 over 12CH4 and preferential desorption of 12CH₄ over 13CH₄ because the adsorption potential of 13CH4 on coal is higher than that of 12CH4; so the migration-fractionation of 12CH4 is more easily occurred. The coal is preferential adsorption of CO₂ over CH4 and preferential desorption of CH4 over CO₂ when compared the adsorption capacity of CO₂ and CH₄, so methane fractionation effect is stronger, especially at high pressure. It provides an approach to quantitative assessment of injection of CO₂ to enhance CH₄ recovery technique. The acting forces between the coal molecule and other gas molecules are calculation by ab initio calculation theory, which explained the adsorption/desorption fractionation effect from the quanta angle. （2） The solution of groundwater which takes place in transmission zone made CO2 preferential to be dissolved, migrate to the stagnant zone and accumulate, which caused the CO2 content is higher than in-situ. Methane carbon isotope has same fractionation effect. That is to say, the 13CH4 content is higher than in-situ. （3） The biogenic methane is produced by two main ways. One is CH₃COOH ferment, the other is CO2 reduction. CO₂ reduction is often quantitatively more important than the aceticlastic ferment. The two biogenic methane all results in methane carbon isotope light. （4） The pyrolysis gas causes methane carbon isotope to heavy.更多还原