青藏高原羌塘盆地有机相展布与成烃模式

青藏高原羌塘盆地中生界海相J_3s,J_3x,J₃b和J_3x4套主要烃源层的成烃生物主要为宏观藻类。J_3s和J₃b烃源层主要发育Ⅱ₁和Ⅱ₂有机相,J_3x烃源层主要发育Ⅱ₁,Ⅱ₂和木本有机相,均从盆地或坳陷中部向盆地东北部逐渐变差;T_3x烃源层各类有机相均有发育,从盆地或坳陷南、北部的Ⅰ或Ⅱ₁有机相向中央隆起区逐渐过渡为木本有机相。羌塘盆地中部多正处于成熟中晚期,侏罗系Ⅱ₁有机相是最有利的生油相带区;北羌塘坳陷中西部多处于高成熟阶段,侏罗系Ⅱ₁有机相是有利的凝析油或轻质油气相带区;羌塘盆地T_3xⅡ₁有机相已经处于过成熟,是有利的生气相带区。 

THE ORGANIC FACIES DISTRIBUTION AND HYDROCARBON-FORMING MODEL IN THE QIANGTANG BASIN, QINGHAI-TIBET PLATEAU

The main Mesozoic marine hydrocarbon source rocks developed in J_3x,J₂b,J_2x and J_3s formations in the Qiangtang Basin,Qinghai-Tibet Plateau.Macro-algae are the main hydrocarbon-forming organisms in these hydrocarbon source formations.The Ⅱ₁ and Ⅱ₂ organic facies developed in the J_3s and J₃b formations.The Ⅱ₁,Ⅱ₂ and lignosa organic facies developed in the J_2x formation.They are getting poorer and poorer from the center of the basin or depressions to the northeast of the basin.In the J_3x formation all types of above mentioned organic facies developed.The Ⅰ or Ⅱ₁ organic facies gradually transited into lignosa organic facies from the south and north of the basin or depressions towards the central uplifted area.The source rocks in the center of the Qiangtang Basin are in the middle to late stages of mature and the Jurassic Ⅱ₁ organic facies are the most favorable oil-generation facies.The source rocks in the center and west of the north Qiangtang Depression are in the stage of high-mature and the Jurassic Ⅱ₁ organic facies are the favorable condensate oil-or light oil-and gas-generation facies.The Ⅱ₁ organic facies in the J_3x formation in the Qiangtang Basin are over mature at present.They are the favorable gas-generation facies.