热成因甲烷碳同位素分布的形成机制

The Mechanism of Carbon Isotope Fractionation During Thermogenic Methane Generation

很多学者从不同的角度用不同的方法模拟了从有机母质 (包括煤和干酪根等气源 )形成天然气 (甲烷 )时的碳同位素分馏效应 ,建立了碳同位素分馏效应的很多模型 ,同时也讨论了催化作用和成烃后作用对天然气碳同位素的影响。但这些理论模型和模拟实验结果都还不能完全地拟合自然界中热成因甲烷碳同位素的分布 ,也未能从本质上完全阐明其碳同位素的分馏机制。其原因是各种模型的前提假设都未能完全满足复杂的自然界条件。今后工作的重点应放在用化学动力学的方法建立更完善的模型上 ,同时也应当重点考虑催化作用和成烃后作用对天然气同位素的影响。

Many authors, from different aspects, have modeled the carbon isotope fractionation effect during gas (methane) generation from organic matters (coals and kerogens) through different approaches. Many models about carbon isotope fractionation have been proposed. At the same time, the effects of catalysis and post-genetic process on gas carbon isotope have also been discussed. But the models can not describe carbon isotopic behavior of thermogenic methane in natural system completely, nor explain the mechanism of its fractionation perfectly. The reason is that the assumptions of the models are not completely suitable to the complexity of natural system. Furthermore, pyrolysis results are used as data source of many models. It is well known that pyrolysis has still a distance with natural process, so that the models, sometimes, can not be applied to real case successfully. To establish more perfect model with chemical kinetic approaches may be a focus in further work. And the effects of catalysis and post-genetic process on carbon isotope fractionation should also be considered.