羌塘盆地油气显示及油源对比

HYDROCARBON SHOW AND CORRELATION BETWEEN OIL ND SOURCE ROCK IN THE QIANGTANG BASIN

南征兵 李永铁 郭祖军

Nan Zhengbing Li Yongtie Guo Zujun

中国科学院, 广州地球化学研究所, 广州, 510640 2. 中国石油勘探开发研究院, 北京, 100083

Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, Guangdong 510640, China 2. Graduate School, Chinese Academy of Sciences, Beijing, 100049, China

羌塘盆地主要发育上侏罗统索瓦组,中侏罗统夏里组、布曲组和上三叠统肖茶卡组4套烃源岩。盆地内已发现多处油气显示,主要有3种类型:一类是索瓦组灰岩裂缝中的液态油苗;另一类为南羌塘坳陷隆鄂尼西布曲组和昂达尔错北索瓦组含油白云岩,以及北羌塘坳陷西部西长梁索瓦组含油灰岩、泥质白云岩;第三类为沥青,主要分布在北、南羌塘坳陷西部和中央潜伏隆起东部等地区。通过多种地球化学方法对比,认为索瓦组灰岩液态油来源于索瓦组泥晶灰岩;索瓦组、布曲组含油灰岩、含油白云岩的油苗来源于索瓦组、夏里组泥页岩;盆内许多沥青,则可能来自索瓦组和布曲组灰岩。

There are 4 sets of hydrocarbon source rocks in the Qiangtang Basin,including the Upper Jurassic Suowa Formation(J3s),the Middle Jurassic Xiali Formation(J2x),the Middle Jurassic Buqu Formation(J2b) and the Upper Triassic Xiaochaka Formation(T3x).Multi points of hydrocarbon show have been discovered in several locations,mainly including 3 types.The first type is the liquid oil seepage in fractures of limestone in the Upper Jurassic Suowa Formation,which was discovered at 114 Daoban,the east of Southern Qiangtang Depression.Four spots of heavy crude oil have been discovered in this area.The second one is seepage in oil-bearing dolostone,which is mainly distributed in the Middle Jurassic Buqu Formation of Longenixi area and the Upper Jurassic Suowa Formation of northern Angdaercuo area in the Southern Qiangtang Depression,and also,oil-bearing limestone and argillaceous dolomite in the Upper Jurassic Suowa Formation have been discovered in the west of the Northern Depression,Xiliangshan area.The last one is the bitumen,which is mainly distributed in the west of Northern Qiangtang Depression and the east of the central buried uplift.It is considered by comparison of geochemical methods that the liquid oil seepage of J3s limestone sources from the J3s micrite,the oil seepage of J3s and J2b oil-bearing limestones and dolostones originates from the J3s and J2x mud shale,and lots of bitumen in the Qiangtang Basin maybe originate from J3s and J2b limestone.

国土资源部“十五”重点科技项目(200102081)

https://doi.org/10.11781/sysydz200805503