高过成熟阶段有机质生气机理研究

With the development of natural gas exploration, the traditional theory of hydrocarbon generation had not interpreted the new characteristics of geology and geochemistry in natural gas exploration, such as the burial depth arriving to 7000-8000m, more than 3.0% Ro of source rock and the carbon isotope rollover to reversal of natural gas. Hence, it is necessary to further research the mechanism of natural gas generated from different organic matter with high-over maturity. Taking coal and the organic matters from marine and lacustrine sediments with different maturity as samples, the following study would be conducted to unravel the mechanism and process of gas generation from organic matter at high-over maturity. (1) Determination of the upper thermal maturity limit of gas generation for different types of organic matter by combining pyrolysis experiments, the evolutions of elementary components and chemical structure. (2) unraveling the mechanism of gas generation from organic matter with high-over maturity and the genesis of carbon isotope rollover and reversal of natural gas by combining the cracking experiments of trimethylbenzene and natural samples and Fischer-Tropsch synthesis experiments. (3) Evaluation the contribution of gas generated from different types of organic matter with high-over maturity on the basis of chemical structure and pyrolysis experiments. This study is significant to improve theory of hydrocarbon generation and make contribution in the exploration of shale gas and deep layer gas.

随着天然气勘探的不断深入，传统的有机质生烃模式已不能圆满解释天然气勘探深度可达7000-8000米、天然气源岩成熟度大于3.0 %Ro、高过成熟阶段许多天然气同位素反转—倒转等地质地球化学特征。因此，对高过成熟阶段不同有机质的生气机理进行更深入的研究很有必要。本研究欲分别以煤、海相和湖相具有不同成熟度的序列样品为对象，从3个方面对高过成熟阶段有机质的生气机理和过程进行研究。（1）在不同类型有机质有机元素组成及化学结构随成熟度演化研究的基础上，结合高过成熟有机质生烃模拟实验探讨三种类型有机质生气结束的成熟度界限；（2）通过单分子化合物（三甲基苯）和高过成熟度实际样品（其结构中只存在甲基侧链）的生气模拟实验以及费托合成实验，以期揭示高过成熟阶段天然气的形成机理和天然气同位素倒转的原因；（3）结合有机质化学结构演化与生烃模拟实验，评价不同类型有机质在高过成熟阶段有机质天然气生成的贡献。

随着天然气勘探的不断深入，传统的有机质生烃模式已不能圆满解释天然气勘探深度可达7000-8000米、天然气源岩成熟度大于3.0 %Ro、高过成熟阶段许多天然气同位素反转—倒转等地质地球化学特征。因此，对高过成熟阶段不同有机质的生气机理进行更深入的研究很有必要。本研究欲分别以煤、海相和湖相具有不同成熟度的序列样品为对象，从3个方面对高过成熟阶段有机质的生气机理和过程进行研究。（1）在不同类型有机质有机元素组成及化学结构随成熟度演化研究的基础上，结合高过成熟有机质生烃模拟实验探讨三种类型有机质生气结束的成熟度界限；（2）通过单分子化合物（三甲基苯）和高过成熟度实际样品（其结构中只存在甲基侧链）的生气模拟实验以及费托合成实验，以期揭示高过成熟阶段天然气的形成机理和天然气同位素倒转的原因；（3）结合有机质化学结构演化与生烃模拟实验，评价不同类型有机质在高过成熟阶段有机质天然气生成的贡献。