西藏伦坡拉盆地北缘中深层古近系牛堡组油气成藏分析

Analysis of petroleum accumulation of Paleogene Niubao Formation in middle-deep underground on north margin of Lunpola Basin,Tibet,China

探讨西藏伦坡拉盆地北缘古近系牛堡组的油气成藏。通过分析伦坡拉盆地油气地质条件,综合含油气系统的研究方法,研究成藏过程和机理。伦坡拉盆地北缘中深层牛堡组的主要烃源为牛二段,属自生自储型油气藏,烃源岩在牛三段沉积末期即开始生烃,大量生烃期为丁青湖组沉积期。伦坡拉盆地北缘的油气成藏过程可以归纳为3个阶段：1渐新世（34~23 Ma B.P.）,古油藏的形成;2渐新世末-中晚中新世（23~13 Ma B.P.）,古油藏的调整;3晚中新世（13 Ma B.P.）至今,古油藏的进一步调整和破坏。青藏高原其他古近纪形成的类似沉积充填盆地也具有相似的油藏形成与破坏过程。

This paper discusses the petroleum accumulation of Paleogene Niubao Formation in Lunpola Basin,Tibet, China. By analysing the petroleum geological conditions and comprehensively researching the petroleum system,this paper studies the accumulation process and mechanism in Lunpola Basin.The main hydrocarbon source of Niubao Formation in the middle-deep layer on the north margin of Lunpola Basin is Member 2of Niubao Formation.This is a self-generating and selfstoring reservoir.The source rocks began to generate hydrocarbon in the end of the third member of the Niubao Formation deposition and generated a large number of hydrocarbon in the period of the Dingqinghu Formation deposition.The accumulation process on the north margin of Lunpola Basin can be summarized into three stages：1the Oligocene epoch（34~23Ma B.P.）,the formation of the ancient reservoir;2late Oligocene-middle and late Miocene（23~13 Ma B.P.）,the adjustment of the ancient reservoir;3late Miocene（13Ma B.P.）to present,further adjustment and destruction of the ancient reservoir.The accumulation idea of this process can be also applied to the other similarPaleogene sedimentary basins of Qinghai-Tibet Plateau.