川东北地区筇竹寺组优质烃源岩分布特征及形成环境

下寒武统筇竹寺组烃源岩是四川盆地及周缘最重要的烃源岩层之一。为明确川东北地区筇竹寺组优质烃源岩分布规律及形成环境,利用测井资料、有机地球化学特征及主-微量元素分析资料等对筇竹寺组烃源岩进行研究。结果表明:筇竹寺组优质烃源岩形成于温暖潮湿、水动力相对较弱的深水陆棚及斜坡-盆地环境,具有中-高的古生产力,整体处于还原-弱氧化条件,为有机质生成及保存提供了有利的沉积环境;纵向上主要发育于地层下部,平面上存在城口-开县裂陷区、巴中-通江地区及五峰-鹤峰一带3个厚度中心,为油气来源奠定了良好的物质基础;与龙王庙组、灯影组优质储层形成良好的源-储配置关系,城口-开县地区及巴中-南江地区是油气勘探的有利区带,值得下一步积极勘探。

Distribution characteristics and formation environment of high quality source rocks of Qiangzhusi Formation in northeastern Sichuan Basin

The Lower Cambrian Qiongzhusi Formation source rocks are one of the most important source rocks in Sichuan Basin and its surrounding areas. In order to clarify the distribution and formation environment of the high-quality source rocks in Qiongzhusi Formation in northeastern Sichuan Basin,data of well logging,organic geochemistry and major-trace element are obtained and studied in this research. Our results show that the highquality source rocks of Qiongzhusi Formation were formed in warm and humid deep-water shelf and slope-basin environment with relatively weak hydrodynamic force. These source rocks are stored in reducing to weak-oxidation environment,which provides the favorable sedimentary environment for the generation and preservation of organic matters. The source rocks are mainly developed in deeper layers in the longitudinal direction and horizontally have three thickness centers in Chengkou-Kaixian rift area,Bazhong-Tongjiang area and Wufeng-Hefeng area. These conditions lay important foundation of oil and gas formation. Besides,a good source-reservoir allocation relationship can be found between the source rocks and the high-quality reservoir rocks in Longwangmiao and Dengying Formation. The abundant distribution of both the reservoir rocks and source rocks in ChengkouKaixian area makes it an attractive location to be prospected in the future work.