蒙古塔木察格盆地塔南凹陷烃源岩特征及潜力评价

Characteristics of source rocks and their potential evaluation in Ta'nan sag of Tamtsag Basin,Mongolia

烃源岩潜力评价是油气田勘探的重要步骤,对于岩性油气藏勘探尤为重要,需考虑多方面因素。受塔南凹陷实际条件的限制,选取烃源岩厚度、有机碳含量、干酪根类型、热解指标、有机质成熟度等5项指标,对研究区下白垩统铜钵庙组、南屯组、大磨拐河组烃源岩特征及潜力进行评价。研究表明,研究区烃源岩特征整体优好;南屯组的烃源岩最优,大磨拐河组次之,铜钵庙组最差。使用"直接乘法"对研究区9小层烃源岩生烃潜力进行综合排队,其中南屯组SQ3-3小层的烃源岩发育最好,铜钵庙组I油组的烃源岩发育最差,其先后顺序及评价为:SQ3-3、SQ3-2、SQ3-5、SQ3-1、SQ3-4、SQ4-1、II油组、SQ4-2及I油组。

The potential evaluation of source rocks is important for the oil and gas exploration,especially for the lithologic reservoir exploration,and should be considered many factors.Limited by the actual conditions of Ta＇nan sag,the authors choose five indicators including hydrocarbon source rock thickness,organic carbon content,kerogen type,pyrolysis index and organic matter maturity,to evaluate the characteristics and hydrocarbon generation potential of source rocks in Early Cretaceous Tongbomiao-,Nantun-and Damoguaihe formations.The study of indicators show that the source rock characteristics are good in general for the studied area,in which the Nantun Formation is the best for source rocks,followed by the Damoguaihe Formaiton,and Tongbomiao Formation which is the worst.By the means of ＂ direct multiplication＂,the authors comprehensively queued the nine sub-layers in this area according to the hydrocarbon generation potential of source rocks,the best source rocks developed in the SQ3-3 sub-layer in Nantun Formation and the worst source rocks developed in I oil group in Tongbomiao Formation.In sequence of the hydrocarbon generation potential of source rocks from best to worst is the SQ3-3,SQ3-2,SQ3-5,SQ3-1,SQ3-4,SQ4-1,II oil group,SQ4-2 and I oil group.