西藏伦坡拉盆地丁青湖组油页岩特征及勘探有利区评价

摘要

Abundant oil shales are exposed on a wide range of scales in the Lunpola Basin,Xizang. In the present paper,three oil shale distribution areas including Jiangriaco,Lunpori and Papa areas are evaluated on the basis of the study of oil shale sections,exploratory trenches,boreholes and relevant experimental data,as well as the thickness,quality,distribution and sedimentary facies of the oil shales in the Lunpola Bain,Xizang. On the whole,the oil shales in the Lunpola Basin have higher ash contents with an average of 81. 76%,medium to higher oil contents with an average of 7. 2%,ultra-low sulfur contents of less than 1% and higher total organic carbon contents with an average of 8. 07%,and thus may be interpreted as the source rocks providing oil source for the reservoir rocks in the Lunpola Basin. The thickness of oil shales tends to be controlled by sedimentary facies. The oil shales are generally arranged along NW or SE orientation in the semi-deep lake and deep-lake sedimentary facies area of the Lunpola Basin. The average oil contents and total organic carbon contents of oil shales are relatively lower in the northwestern part and higher in the southeastern part of the Basin. Estimated from the thickness and extent of oil shales,the Papa area is believed to be the most favorable area for the oil shale exploration due to larger thickness,wider EW-oriented distribution,higher average oil contents and total organic carbon contents.%西藏伦坡拉盆地出露大规模的油页岩.通过研究油页岩的剖面、探槽、钻井及相关实验数据,根据油页岩厚度、分布范围及沉积相特征,结合油页岩品质特征,对蒋日阿错、伦坡日及爬爬3个油页岩分布区进行了评价.研究表明,伦坡拉油页岩总体为高灰分(平均81. 76%)、中高含油率(平均7. 2%)、特低含硫量(小于1%)型油页岩,其有机碳含量高(平均8. 07%),产烃潜量较大,可作为烃源岩为伦坡拉盆地的油藏提供油源.油页岩厚度受沉积相带控制,主要呈北西-南东向断续分布于盆地半深湖-深湖相区.油页岩平均含油率、有机碳含量总体呈北西部低、南东部较高的趋势.综合油页岩厚度及油页岩展布范围,爬爬地区油页岩具有厚度较大、东西向展布最广、平均含油率及有机碳含量高的特征,是最有利的油页岩勘探区,伦坡日、蒋日阿错地区则次之.