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选择泥炭和褐煤进行热模拟试验并开展对比研究,目的是全面获得煤系有机质生烃特征。通过对草本泥炭和褐煤的热模拟实验液态产物饱和烃进行色谱—质谱分析得到,在泥炭和褐煤热模拟样品中均检测出丰富的甾族系列化合物,且以C29甾烷占优势。研究发现,随热模拟温度增高,C29甾烷相对含量减少,温度在350℃之后趋于稳定;而C27甾烷和C28甾烷相对含量具有增加的趋势,暗示了C29甾烷的去甲基效应。C2920S/(20S+20R)值和C29ββ/(ββ+αα)值可以判识样品是否成熟或未熟,是良好的成熟度指标。∑重排甾烷/∑规则甾烷值可以区分成样品成熟度。研究发现,在低演化阶段,泥炭和褐煤模拟曲线存在显著差异,而在高演化阶段,二者吻合较好。所以,对比研究泥炭和褐煤的地球化学特征,对认识煤系有机质生烃特征具有重要意义。
Peat and lignite are selected for thermal simulation test and comparative study, the purpose is to fully obtain coal-bearing organic matter hydrocarbon generation characteristics. Chromatography-mass spectrometry (LC-MS) analysis was performed on the thermodynamic simulation experiments of herbaceous peat and lignite. Rich steroidal compounds were detected in peat and lignite thermal simulation samples, and C29 steranes dominated. The results show that the relative content of C29 steranes decreases with the increase of thermal simulation temperature, and tends to be stable after the temperature reaches 350 ℃. However, the relative content of C27 steranes and C28 steranes has an increasing trend, suggesting the demethyl effect of C29 steranes . The values of C2920S / (20S + 20R) and C29ββ / (ββ + αα) values can be used to judge whether the sample is mature or not, which is a good maturity index. Σ Rearrangement sterane / Σ regular sterane value can be divided into sample maturity. The study found that in the low evolution stage, the simulated curves of peat and lignite have significant differences, while in the high evolution stage, the two agree well. Therefore, comparing the geochemical characteristics of peat and lignite is of great significance for understanding the characteristics of hydrocarbon generation of coal-bearing organic matter.