塔里木盆地下寒武统肖尔布拉克组烃源岩特征及分布预测

Characteristics and Distribution Prediction of Source Rocks of Lower Cambrian Sholbluk Formation in Tarim Basin

肖尔布拉克组烃源岩及其分布是众多学者关注的问题。该文基于野外露头及盆地钻井资料,分析了肖尔布拉克组烃源岩的岩性组合及沉积环境特征,结合地震资料综合预测肖尔布拉克组烃源岩的分布。塔里木盆地肖尔布拉克组烃源岩根据沉积环境可分为台地潟湖和斜坡-陆棚相两种类型,其中台地潟湖相烃源岩主要以细-粉晶白云岩和泥质云岩为主,TOC为0.16%~2.68%,受前寒武系古构造格局控制,主要发育在台地内部形成的潟湖周缘,累计厚度40~50 m;斜坡-陆棚相烃源岩以泥质灰岩、泥晶灰岩及泥岩为主,TOC为0.06%~4.00%,主要发育在缓坡台地背景下的外缓坡-陆棚沉积环境,烃源岩累计厚度约30~120 m,越靠近陆棚方向,TOC含量越高。研究结果是塔里木盆地下寒武统烃源岩的进一步补充,并且为盆地深层寒武系的勘探提供一定的借鉴。

Many scholars pay attention to the development and distribution of source rocks in Sholbluk Formation.Based on the field outcrop and basin well drilling data,this paper analyzed the lithologic combination and sedimentary environment characteristics of source rocks in Shorbluk Formation,and combined with seismic data,the distribution of source rocks in Shorbluk Formation was comprehensively predicted.According to the sedimentary environment,the source rocks of Shoerbluk Formation in Tarim Basin can be divided into two types:platform lagoon facies and slope-shelf facies.The source rocks of platform lagoon facies are mainly fine silty dolomite and argillaceous dolomite,with TOC of 0.16%~2.68%.Controlled by the paleotectonic pattern of Precambrian,they are mainly developed around the lagoon facies formed in the platform,with a cumulative thickness of 40~50 m.The source rocks of slope-shelf facies are mainly argillaceous limestone,micrite and mudstone,with TOC of 0.06%~4.00%.They are mainly developed in the outer gentle slope-shelf sedimentary environment under the background of gentle slope platform,with a cumulative thickness of 30~120 m.The closer to the shelf direction,the higher the TOC content.The research results are a further supplement to the lower Cambrian source rocks in Tarim Basin,and provide a certain reference for the exploration of deep Cambrian in the basin.