吐鲁番-哈密盆地烃源岩的母质类型与热演化特征

TYPE OF SOURCE MATERIALS IN THE SOURCE FORMATION IN TURPAN-HAMI BASIN AND THEIR FEATURE OF THERMAL EVOLUTION

吐鲁番-哈密盆地有海湖相暗色泥岩和湖沼相煤系两大类烃源岩系,横向分布在哈密、台北和托克逊三大凹陷内,纵向集中堆积在侏罗系、三叠系、二叠系三大套五个层组之中。其有机质丰度均达成烃标准,多属Ⅱ—Ⅲ,干酪根型,尤以侏罗纪煤系有机质丰度最高,一般较正常泥岩高十几到几十倍。这些有机质在较低的热力学条件下,可直接转化成液态烃。本文首次提出了该盆地煤系成烃门限低(R_■>0.4%)、暗色泥岩成烃门限相对较高(R_■>0.5%)的差异成烃模式。

There are two sets of hydrocarbon source formations-marine-lake phases dark mudstone and lake-marsh phases coaliferous formation,in Turpan-Hami basin.Regionally they are distributed in Hami,Taibei and Tuokexun sub depressions,and they are distributed in five formations belonging to three systems of Jurassic,Triassic and Permian in the profile.The abundance of organic matters in them reach the hydrocarbon generation level and most of these source materials are kerogens belonging to types Ⅱ and Ⅲ_1 and the abundance is the highest in Jurassic-being tens fold than those in the conventi- onal mudstones.These organic matter can transform to liquid hydrocarbons directly under relatively low thermal conditions.Based on these results with an integration of informations both at home and abroad,the author suggest, for the first time a model,that coaliferous formation has a lower threshold of hydrocarbon generation(Ro>0.4%),while dark mudstone has a relatively high threshold of hydrocarbon generation(R_o>0.5%).