【摘要】 马五段是鄂尔多斯盆地中部气田下奥陶统主力气源岩中的主力生烃层段。通过对比４口井２３个样品下奥陶统马五段气源岩氯仿沥青“Ａ”、氯仿沥青“Ｃ”含量，族组成及饱和烃馏分生成物标记化合物地化特征，认为该段气源岩氯仿沥青“Ａ”和氯仿沥青“Ｃ”具同源性，但前者成熟度略高于后者，前者含量及其总烃含量随样品有机碳值增高而增大；相反，后者含量及其总烃含量随样品有机碳值增大而减小；二者的沥青转化率和烃转化率都随ＴＯＣ值增大而变小。根据二者含量、总烃含量以及沥青转化率和烃转化率与样品有机碳关系的综合研究，提出马五段碳酸盐岩气源岩有机碳含量下限值可确定为０．０４％。最后认为，评价高、过成熟阶段碳酸盐岩大中型气田气源岩不仅要依据有机质丰度的高低，氯仿沥青“Ａ”的数量和质量，还必须考虑到氯仿沥青“Ｃ”的数量和质量，此外还要结合沥青转化率和烃转化率加以综合判识。更多还原

【Abstract】  1m 5(i.e.the fifth member of Majiagou Formation,Lower Ordovician)is the major hydrocarbon source interval in the major gas source rocks of the Lower Ordovician in Centre gas field in Eerduosi Basin.Through contrasting the chloroform bitumen “A” content,chloroform bitumen “C” content and group composition,and the geochemical characteristics of saturated hydrocarbon distillate labeled compound in 23 samples from O 1m 5 gas source rocks in 4 wells,it is thought that the chloroform bitument “A” and choloroform bitument “C” of the gas source rocks in the interval are of consanguineous property,however the maturity of the former is higher than that of the latter,and the former′s content and its total hydrocarbon content increase with the raise of organic carbon content in the samples;on the contrary,the latter′s content and its total hydrocarbon content decrease in the same case;and that the bitumen and hydrocarbon conversion rates of the two decrease with the increase of total organic carbon value.According to a comprehensive research on the relations of the choloroform bitumen “A” content,choloroform bitumen “C” content,total hydrocarbon content,bitumen conversion rate and hydrocarbon conversion rate with the organic carbon content in the samples,it is proposed that the cutoff of the organic carbon content in the gas source rock of O 1m 5 carbonate rock may be determined as 0.04%.Finally,it is thought that not only the size of organic matter abundance and the quantity and quality of choloroform bitumen “A”,but also those of choloroform bitumen “C” must be all considered in evaluating the gas source rocks in large and medium sized gas fields of high and post maturity carbonate rocks.In addition,a comprehensive judgement must be also carried out in combination with the bitumen and hydrocarbon conversion rates.更多还原