Abstract:The comprehensive analysis of geochemistry and petroleum geology is used to study petroleum source and accumulation characters of Archean metamorphic buried hill of Xinglongtai in the west Sag of Liaohe Depression.The results show that the oil gas reservoir sequence of the buried hill can be divided into two systems of oil pool formation.One is the high pressure system near the top of the buried hill,the other is the normal pressure system in the inner of the buried hill.The crude oils from two systems have similar geochemical characters,which is characterized by the concentrations of saturated hydrocarbons more than 75 percent,low isoprenoid alkane contents,Pr/Ph around 1.0,paucity of gammacerane,C27,C28,C29 sterane distributed in”V” shape.They are the highest maturity oils of Xinglongtai and both from the highly mature source rocks of Es3 in Qingshui Subsag.Reservoring period of two systems is very close,however,two systems are distinctly different in system of migration passage and main factors controlling hydrocarbon accumulation.Reservoir forming mode of the buried hill can be characterized by the unidirectional oil gas source,multiple transportation system(unconformity,fault and fissure in the buried hill),bidirectional migration(lateral migration and vertical migration),multi period accumulation.
