黔中隆起及周缘下寒武统牛蹄塘组页岩气勘探前景

摘要

文章基于黔中隆起及周缘地区下寒武统牛蹄塘组黑色页岩的野外露头，并与周边钻井资料类比，通过野外地质观测、样品显微薄片等多项实验测试，以地层沉积、岩石学、有机地球化学和泥页岩含气性等为重点，对其下寒武统牛蹄塘组页岩气形成的成藏条件与勘探前景进行了分析。结果表明黔中隆起及其周缘地区下寒武统牛蹄塘组主要发育以盆地相—深水陆棚沉积环境控制的富有机质泥页岩，富有机质泥页岩厚度大(80~160 m)，有机质丰度高(平均 TOC 含量3.63%)，有机质类型好(Ⅰ-Ⅱ1型)，热演化程度高成熟―过成熟(Ro>1.55%)，石英等脆性矿物含量丰富(平均>46%)，泥页岩中发育微米至纳米级微孔隙和微裂缝，且有较好的保存条件，有利于页岩气的形成与富集，具有较好的勘探前景。%This paper initially conducted research on the field outcrops of the black shale of the Lower Cambri-an Niutitang Formation in Qianzhong Uplift and its periphery,and compared it with data of peripheral drill-ing boreholes.Through several tests including field geological observation and sample micro-section,the pa-per focused on the stratigraphic deposition,petrology,organic geochemistry and gas-bearing capacity of the mud-shale,and analyzed reservoir forming conditions and exploration potential of shale gas from the Lower Cambrian Niutitang Formation.The results indicated that the Lower Cambrian Niutitang Formation in Qianzhong Uplift and its periphery mainly cultivated organic-matter-rich mud-shale which was controlled by basin facies-deep shelf sedimentary environment.The thickness of organic-matter-rich mud-shale is great (80-160m),and the abundance of organic matter is high (mean TOC content is 3.63%),and the type of or-ganic matter is favorable (Type I-II1 ),and the thermal evolution degree is highly mature to over mature (Ro>1.55%),and the content of brittle mineral like quartz is abundant (mean value >46%).Micron-grade and nanoscale micropore and microfracture are developed in the mud-shale and under favorable preservation con-ditions they are in favor of the formation and enrichment of shale gas with great exploration potential.