CHARACTERISTICS OF UPPER JURASSIC SUOWA FORMATION SOURCE ROCK IN THE QIANGTANG BASIN OF NORTHERN TIBET

Over 200 oil and gas shows were discovered so far in the Qiangtang Basin,of which including 5 oil shows and much oil shale shows.It indicates that the source rocks have favorable conditions to form gas and oil in the Qiangtang Basin.The mainly source rock of Upper Jurassic Suowa Formation is carbonate rocks in the Qiangtang Basin.It's thickness is from tens meters to hundred meters.The mean content of organic caborn is 0.1% to 1.90%.It is mainly middle to good source rock.The following source rock of Upper Jurassic Suowa Formation is mudstone.It's mean content of organic caborn is 3.71% to 27.14%. It is mainly good source rock,only distributes in the middle and west of the North Qiangtang Depression.The organic matter type is Ⅱ₁ through kerogen analysis.The vitrinite reflectance is 0.94% to 2.7%.The source rock is at stage of mature to post maturity.The source rock of Suowa Formation was uplifted and denuded because of the effect of tectonic movement.The research results show that Suowa Formation source rock has bad contribution to hydrocarbon accumulation in the whole Qiangtan Basin.But it is still important hydrocarbon source rock in the west and northeast of the North Qiangtang Depression.