古生代未成熟藻干酪根水岩反应特征

CHARACTERISTICS OF HYDROPYROLYSIS OF PALAEOZOIC IMMATURE ALGAL KEROGEN

本文通过对采自爱沙尼亚库克赛特奥陶系油页岩水岩反应过程的研究，探讨了未成熟藻干酪根的油气生成特征．通过对热模拟实验的分析发现，藻干酪根的生烃潜力是相当高的，但其未成熟油生成量却是相当低的，其水岩反应较好地再现了油气的演化过程与特征，很难形成规模性的油气藏。该藻干酪根液态富范围较宽，成熟阶段倾向于生油，不利于成气，且在生成的气中非烃占优势．在高成熟阶段由于油的裂解可大量生成轻质烃和凝析油，早期生成的气态烃较少，晚期气态烃量增加。气态产物中以CO2占优势，气态烃中甲烷含量最高，仅含少量烯烃。在正异构烃的组成中，正构烃含量很高，导构烃含量较少。在液态产物中，热解油食量占优势，生油高峰在330℃附近。模拟时间对水岩反应有一定影响，模拟时间的延长利于油的裂解和气态烃的增加。

Through a study of hydropyrolytic process on oil shale samples colleced from Kukesait, Estonia, the characteristics of oil/gas generation from immature algal kerogen are approached in this paper. It is con- cluded that although it does show a quite high potential of hydrocarbon generation as seen by an analysis of thermal simulation experiments, the amount of immature oil yielded by algal kerogen is rather low. Its hy- dropyrolysis can well reproduce the process and characteristics of oil/gas evolution, indicating that it is dif- ficult to form algal kerogen-derived oil/gas pools on a considerable scale. With a wider range of liquid win-dow, in the mature stage, algal kerogen tends to generate oil rather than gas; moreover, the generated gas will be dominated by non-hydrocarbons. In the higher mature stage, a large quantity of light hydrocarbons and condensates is generated by the cracking of oil; and the early stage is characteristic of less gaseous hy-drocarbons generated, while in the late stage, they would increase. The gaseous products are dominated by CO2, and the content of methane is the highest among gaseous hydrocarbons, containing only a little amount of alkenes. The normal-isohydrocarbon composition is comprised of a very high content of n-alka-nes but less isohydrocarbons. Pyrolytic oil is predominating over the liquid products, with the peak oil generation around 300℃.The simulation time would affect the hydropyrolysis to certain extent, and a prolonged time would favourable for oil-cracking and increasing gaseous hydrocarbons.