青藏高原羌塘盆地有机相展布与成烃模式

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

秦建中

Qin Jianzhong

中国石油化工股份有限公司, 石油勘探开发研究院, 无锡石油地质研究所, 江苏, 无锡, 214151

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214151, China

青藏高原羌塘盆地中生界海相J3s,J3x,J3b和J3x4套主要烃源层的成烃生物主要为宏观藻类。J3s和J3b烃源层主要发育Ⅱ1和Ⅱ2有机相,J3x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;T3x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T3xⅡ1有机相已经处于过成熟,是有利的生气相带区。

The main Mesozoic marine hydrocarbon source rocks developed in J3x,J2b,J2x and J3s 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 J3s and J3b formations.The Ⅱ1,Ⅱ2 and lignosa organic facies developed in the J2x formation.They are getting poorer and poorer from the center of the basin or depressions to the northeast of the basin.In the J3x 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 J3x formation in the Qiangtang Basin are over mature at present.They are the favorable gas-generation facies.

https://doi.org/10.11781/sysydz200603264