松辽盆地白垩纪海侵事件与油气的早期生成

海侵事件是松辽盆地的重要地质事件之一，其主要特征是存在着甲藻甾烷和Ｃ３１甾烷，朝长地区长２０井原油为典型的未熟－低熟油。油源对比表明，未熟－低熟油的源岩与白垩系青山口组一段海侵地层有关，因而说明油气的早期生成与海侵事件密切相关。

Transgression and Generation of Low-matural Hydrocarbon in Songliao Basin

The geological event of the Cretaceous period involved important geological events such as marine transgression The existence of high abundance of dinosterane in the mudstone of the first section of the Qingshankou formation and member 1 and member 2 of the Nenjiang formation indicates two periods of marine transgression The relative content of dinosterane in the samples from the first section of the Qingshankou formation is larger than that of member 1 and member 2 of the Nenjiang formation, which implies that there is a relatively high salinity in the sedimentation period of the first section of the Qingshankou formation C 31 sterane can be also regarded as a marker of transgression The research result shows that early generation of hydrocarbons is closely related to marine transgression strata Several factors may attribute to this: (1) The excellent source rock has been formed in the high water level of marine transgression;(2)Fluctuation of marine transgression leads to formation of source rocks,reservoir rocks and cap rocks, which is important to oil pool formation; (3)The marine transgression will cause the increase in salinity of water media, such that the source rocks will have very good organic matter type; (4) Some kinds of algae such as dinoflagellates, diatoms, prynesiophytes, rich in biological lipids and weakly polymerized, can generate hydrocarbons in the early stage