泥炭的热模拟研究──过渡带气形成机理探讨

Study on Thermal Simulated Peat──A Discussion on the Genetic Mechanism of Transitional Zone Gas

本文对现代泥炭进行了低温长时间模拟实验研究，并探讨了过渡带气的形成机理。甘南泥炭气、液态烃产率高。液态烃由热解油和残余气仿沥青“Ａ”两部分组成，热解油中以Ｃ５─Ｃ１４较轻馏分为主，残余氯仿沥青“Ａ”则以非烃、沥青质为主。随热演化程度增高，烃类增加，非烃和沥青质急剧减少。模拟气体组成以非烃气体（ＣＯ２等）为主，随温度升高，气态烃产率升高，烃类气体中以甲烷为主。２００℃～４００℃温度下产生的甲烷碳同位素δ１３Ｃ为－５３．８２～－３３．６６‰。研究表明低热演化阶段伴随腐殖物质的降解和干酪根的分子重排作用能产生甲烷同位素较轻的生物－热催化过渡带气。

This paper made a thermally simulating experiment on modern peat under low temperatures and longer time, and discussed the genetic mechanism of transitional zone gas. Gannan peat has relatively higher yields of gaseous and liquid hydrocarbons under simulation. Liquid hydrocarbons are made up of thermolytic oil and residual chloroform 'A'. The former is dominated by C6-C14 light hydrocarbons, and the latter is dominated by NSO compounds and asphaltenes. With increasing thermal evolution, the relative content of saturated and aromatic hydrocarbons increases whereas that of NSO compounds and asphaltenes decreases rapidly. Gas compositions for simulated peat are dominated by non- hydrocarbon gases, such as CO2 and N2. With increasing simulation temperatures, gaseous hydrocarbon yields increase rapidly. Gaseous hydrocarbons include C1 -C5 hydrocarbon gases, mainly methane. Carbon isotope values of mathane produced at temperature of 200～400℃ are-53. 82～-33. 62‰.The research indicates that at low thermal evolution stage associated with humic acid decomposition and kerogen rearrangement, bio - thermal catalytic transitional zone gas with lighter carbon isotope value of methane can be generated.