吉木萨尔凹陷芦草沟组有效源岩有机碳含量下限分析

通过对准噶尔盆地吉木萨尔凹陷吉174井芦草沟组烃源岩发育与有机地化特征的分析，根据排烃机理，利用可溶有机质转化率、热解S₁/w（TOC）参数与有机碳含量的关系，确定了泥岩类烃源岩排烃有机碳含量下限值。总体上，吉174井芦草沟组泥质烃源岩发育，不同岩性泥岩生排烃条件相近，但由于不同岩性泥岩的矿物组成、有机质特征的差异，导致其排烃的有机碳含量下限值有所不同，较纯泥质烃源岩、粉砂质烃源岩、灰质和云质有效烃源岩的有机碳含量下限值分别为2.50%，2.80%，1.45%，1.30%。含碳酸盐的有效烃源岩相对所占比例要高于较纯泥岩和粉砂质泥岩，但都超过了50%。吉174井芦草沟组泥质有效烃源岩发育，有机质丰度下限值明显较高，对油气藏有重要贡献。

Lowest limit of organic carbon content in effective source rocks from Lucaogou Formation in Jimusar Sag

The generation and organic geochemical features of source rocks from the Lucaogou Formation in Ji174 well area in the Jimusar Sag of the Junggar Basin were studied. According to hydrocarbon expulsion laws as well as the relationships between soluble organic matter transformation rate, pyrolysis S₁/w(TOC) and organic carbon content, the lowest limit of organic carbon content for hydrocarbon expulsion in lutaceous source rocks was determined. In the Lucaogou Formation in Ji174 well area, lutaceous source rocks developed well, and their hydrocarbon generation conditions were similar even though the lithology was various. Due to the differences in mineral compositions and organic matter characteristics, the lowest limit of organic carbon content for hydrocarbon expulsion was different. For pure lutaceous, silty, calcareous and dolomite source rocks, the lowest limits were 2.50%,2.80%,1.45% and 1.30%, respectively. The carbonate-containing effective source rocks took larger proportions than pure and silty mudstones, all over 50%. It was concluded that in the Lucaogou Formation in Ji174 well area, lutaceous effective source rocks were well-developed, and the lowest limits of organic carbon content were higher, which were favorable for hydrocarbon reservoirs.