塔里木盆地塔东地区寒武系烃源岩分布及有利区带评价优选

Distribution of Cambrian source rocks and evaluation and optimization of favorable zones in East Tarim Basin

塔里木盆地塔东地区寒武系烃源岩是近年来诸多学者研究的热点,对其分布及认识还存在一定的分歧,已成为制约寒武系勘探及区带优选的重要因素。基于野外露头及盆地内钻井资料的认识,分析塔里木盆地寒武系烃源岩的沉积环境;根据沉积环境和形成年代,将塔东地区寒武系烃源岩分为缓坡型烃源岩和陡坡型烃源岩。缓坡型烃源岩是玉尔吐斯组同时期沉积的烃源岩,该类型烃源岩沉积主要受控于前寒武系古地貌,厚度中心位于满加尔坳陷西北侧,烃源岩厚度约为20~40 m;陡坡型烃源岩是早寒武世晚期-晚寒武世台缘斜坡-盆地沉积环境发育的烃源岩,主要发育在满西地区轮南-古城弧形条带内,最大厚度约为150 m。结合塔东地区2类烃源岩的分布特征,优选轮南地区盐下白云岩及古城低凸起北部中上寒武统台缘带为塔东地区有利勘探区带。

Cambrian source rocks in Tarim Basin have been the focus of many scholars'research in recent years.There are still some divergences on their distribution,which become an important factor restricting Cambrian ex⁃ploration and zoning optimization.Based on the knowledge of outcrop and drilling data in the basin,the sedimenta⁃ry environment of Cambrian source rocks is analyzed in this paper.According to the sedimentary environment and development time,the Cambrian source rocks are divided into mild-slope style rocks and steep-slope style rocks in East Tarim.The mild-slope source rocks,deposited in the same period of the Yuertus Formation,is mainly controlled by the pre-Cambrian palaeogeomorphology.The thickness center is located in the northwest side of the Manjiar Depression,and the thickness of the source rocks is about 15-40 m.The steep-slope source rocks,devel⁃oped in the sedimentary environment of the platform margin slope-basin,is located in the Lunnan-Gucheng arc belt in Manxi area,with a maximum thickness of about 150 m.Based on the distribution characteristics of two types of source rocks in East Tarim area,dolomite of Lunnan area and the Middle-Upper Cambrian platform mar⁃gin belt in the north of Gucheng low uplift are selected as favorable exploration zone in East Tarim Basin.