Abstract:

Crude oils and source rocks in Raoyang and Beijing-Tianjin sags as well as in the east slope of Ningjin uplift of Jizhong(central Hebei)depression are compared by the parameters of gonane and terpane stereoisomers.It is shown in a preliminary way that oils in Sinian buried hills of Renqiu Oilfield might come from different sources around,i.e.from the 1st and 3rd members of Shahejie Formation (E_3s);oils in Ordovician in the north slope of this field from Kongdian Formation (E_2k)of Bacian sag;oils Beijing-Tianjin region primarily from the 4^th member of Shahejie Formation and Kongdian Formation,whereas oils in the 3^rd member of Shahejie Formation might come from insitu.Oils in the 4th member of Shahejie Formation in th east slope of Ningjin uplift still preserved clear marks of terpanes,though they were subjected to biological degradation,this implies that these oil might come from the saline 4^th member of Shahejie Formation. Thermal evolution of source rocks in Jizhong depression is discussed with three gonane and terpane parameters,which can accurately reflect the threshold depth and the peak of oil generation.According to the abundance of gonanes and terpanes,as well as the amount of gammacerane in saturated hydrocarbons,the authors suggest that the organic matters in Raoyang sag is better than that in Beijing-Tianjin sag.