川南下寒武统筇竹寺组页岩气形成条件及资源潜力

Shale gas generation and potential of the Lower Cambrian Qiongzhusi Formation in Southern Sichuan Basin,China

利用四川盆地南部地区最新钻探的井下资料、周边露头地质调查资料及大量样品的分析测试结果,从富有机质页岩区域展布、地球化学特征、岩石储集特征、含气性等方面研究川南地区下寒武统筇竹寺组页岩气形成条件与资源前景。研究区筇竹寺组有机质含量高(TOC值为0.55%～25.70%,平均值大于2%),页岩有效厚度大(黑色页岩厚60～300 m),脆性矿物含量较高(大于40%),页岩中发育丰富的纳米—微米级孔隙和微裂缝,含气量高(页岩含气量0.27～6.02 m3/t,平均1.90 m3/t),有利于页岩气的形成与富集。钻井过程中筇竹寺组气显示频繁并获得了工业性突破,是目前中国最有利的页岩气勘探开发层系之一,综合对比研究认为威远、叙永—筠连地区是研究区内筇竹寺组页岩气勘探开发最有利的地区。

According to the latest drilling data,the geologic survey of surrounding outcrops and the laboratory test results of rock samples,this paper studies the regional distribution,geochemical and reservoir characteristics and gas concentration of organic-rich shales to reveal the shale gas generation and potential of the Lower Cambrian Qiongzhusi Formation of the Southern Sichuan Basin.The study area features high organic content（with TOC between 0.55% and 25.7%,average of more than 2%）,great net shale thickness（of 60— 300 m）,high brittle mineral content（over 40%）,abundant micro-and nanometer-sized pores and micro-fractures,and high gas content（0.27—6.02 m3/t,average of 1.90 m3/t）,which is in favor of the generation and accumulation of shale gas.The Lower Cambrian Qiongzhusi Formation is one of the most favorable strata which has frequent gas show and industrialization breakthrough during drilling,and the Weiyuan and Xunyong-Junlian areas are two most realistic and favorable targets for shale gas exploration and development.