层序地层地球化学在海拉尔盆地呼和湖凹陷烃源岩评价中的应用

呼和湖凹陷是海拉尔盆地未来油气勘探的新战场,目前勘探程度较低,关于烃源岩的认识比较薄弱,精细评价该区烃源岩对有利区带预测具有重要意义。以层序地层学和地球化学理论为指导,综合运用有机碳(TOC)、生烃潜量Pg(S1+S2)、氯仿沥青"A"、干酪根元素特征、岩石热解特征和干酪根类型指数(KTI)及显微组分特征、镜质组反射率(Ro)和源岩甾萜烷特征等方面资料,从不同层序和同一层序不同体系域对呼和湖凹陷的烃源岩特征进行综合评价研究。结果表明,呼和湖凹陷烃源岩非均质性特征明显,烃源岩生烃的层位主要分布于Sq4、Sq3和Sq2层序的湖侵体系域和高位体系域,尤其是Sq3和Sq2层序的湖侵体系域中。应用这一方法进行烃源岩评价,不仅对呼和湖凹陷的油气勘探工作具有重要的意义,同时对于勘探程度低、钻井稀少的含油气盆地中的烃源岩评价工作更为有效。

Sequence stratigraphic geochemistry and its application to the evaluation of source rocks of Huhehu Sag in Hailar Basin

Huhehu sag is the new area of oil and gas exploration in Hailar basin in future.Exploration in this area and research of source rocks are still poor.Therefore,detailed evaluation for source rocks will be of great importance to forecasting of favorable zones.Based on the sequence stratigraphy and geochemical theory,this study conducted comprehensive evaluation to characters of source rocks in Huhehu sag from the various sequences and systems in the same sequence using the total organic carbon,hydrocarbon generating potential,chloroform bitumen "A",element characteristic of kerogen,pyrolysis characteristic of rocks,kerogen types index,maceral characteristic,vitrinite reflectance and steroid terpane characteristic.The results show that the Huhehu sag is characterized by heterogeneous source rocks,with the layers of hydrocarbon generating occurring in the TST and HST of Sq4,Sq3 and Sq2,especially in source rocks of the TST of Sq3 and Sq2.Therefore,application of this method in evaluation of source rocks is not only of very important significance in exploration of Huhehu Sag but also very effective in evaluation of the oil-gas bearing basins which are not explored well and drilled and poorly drilled.