泥炭的热模拟实验及其在煤层气研究中的应用

Thermal simulation of peat as an original matter of coal generation and its application to the study of coalbed gas

  • 摘要: 采用高温高压多冷阱热解实验装置,在温度和压力分别为336.8~600℃和 50MPa,升温速率为 20℃/h和 2℃/h条件下,对泥炭进行了热解生气的模拟实验,获得了烃类甲烷和C2-C5气体以及非烃二氧化碳、氢气和硫化氢气体的产率和体积分数数据,研究了热模拟产物气体的组分特征和热演化过程。结果表明,泥炭高温热解产物气体主要由非烃二氧化碳气体组成,其次为烃类甲烷和C2-C5气体。随着实验温度的增高,非烃气体体积分数呈下降趋势,烃类气体体积分数呈上升趋势。不同升温速率实验条件下,泥炭样品热解生气表现出不同的特征,主要体现了时间因素控制着泥炭的生烃过程和生烃量,这符合化学反应动力学时间与温度之间互补的原理。并且与煤岩热解生气特征进行了对比,表明泥炭比煤岩具有更高的产烃气能力。根据热模拟实验研究结果,探讨了煤层气形成方面的地球化学意义。

     

    Abstract: High temperature and pressure apparatus is emp loyed in the simulation experiment on gas generation of peat as an original matter of coal generation, under conditions of temperature ranging from 336.8~600℃, a pressure of 50 MPa and two rates of temperature rise of 20℃/h and 2℃/h. The yields of gaseous prod ucts, such as methane, C2-C5 hydrocarbon gas, carbon dioxide, hydrogen and sulfured hydrogen, and their relative percent contents are obtained; the gaseous component and evolution of thermal simulaiting products of peat are studied. The results show that the gaseous products are mainly comprised of carbon dioxide, methane and C2-C5 hydrocarbon gas. With the experimental temperature increas ing, non-hydrocarbon gases tend to decrease but hydrocarbon gases increase. The gas generation in the process of peat pyrolysis exhibits various characteristics under the conditions of different rates of temperature rise. This reflects that the process and amount of hydrocarbon gas generation of peat are mainly contro lled by time factor, which is consistent with the chemical reactive kinetic prin ciple that time and temperature are complementary each other. Based on the therm al simulating results, the geochemical significance for coalbed gas generation is discussed. The result indicates that peat has a higher potential of hydrocarbo ngeneration than that of coal rock by contrasting to the characteristics of hyd rocarbon gas generation of coal rock.

     

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