勘探实践和研究表明，马朗凹陷二叠系芦草沟组源内油气为页岩油，该原油C29甾烷立体异构化参数 w（20S）/w（20S＋20R）、w（ββ）/w（αα＋ββ）均为0．2～0．4，为典型低熟原油。通过对芦草沟组烃源岩地球化学和有机岩石学特征的综合研究，发现低熟页岩油的生烃母质为原生的富氢无定形体，这些无定形体在沉积早期经历过细菌的改造作用，致使其具有特殊的生烃演化模式，即低熟成熟阶段早期（ Ro 为0．55％～0．75％）处于生油高峰，对应埋深为1800～2900 m ，埋深大于或小于该主峰带，烃源岩生烃能力急剧降低。泥岩生烃模拟实验、热解、抽提等实验数据表明：芦草沟组低熟页岩油正是位于该主生带的源岩所生，处于生烃带的源岩区即为马朗凹陷低熟页岩油富集的有利地区。%Exploration practices and researches show that hydrocarbon in the source rocks of the Lucaogou Formation of the Permian ,Malang sag was shale oil and also a typical low-mature oil with both sterane isomerization parameters (20S/(20S + 20R) and ββ/(αα + ββ)) between 0 .2 and 0 .4 . Through comprehensive study of geochemical and organic petrology characteristics in the hydrocarbon source rock of Lucaogou Formation ,we find that the parent material of this low-mature shale oil was hydrogen-rich amorphous solid and experienced the bacteria transformation in the early sedimentary stage , w hich resulted in the formation of the particular hydrocarbon-generating evolution model . Namely ,during the low-mature and early mature stage with Ro values 0 .55% 0 .75% ,there is an oil generation peak w hose burial depth ranges from 1 800 to 2 900 m , and the hydrocarbon-generating potential of source rock drops sharply beyond the main hydrocarbon-generating zone . The results of hydrocarbon-generating simulation experiments , rock pyrolysis analysis and organic extraction of mudstone prove that the low-mature shale oil in Lucaogou Formation was generated by the hydrocarbon source rocks within the range of main hydrocarbon-generating zone ,where was the beneficial places of shale oil accumulation .
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