In order to achieve the shale gas production goal (300× 108 m3 in 2020) in China's 13th Five-Year Plan,it is necessary to seek new prospective areas of shale gas exploration and development.The Xuanhan-Wuxi shale gas license block in the eastern Sichuan Basin presents a favorable shale gas potential,thus for the sake of the researches into the marine shale stratigraphy in the Upper Ordovician Wufeng Fm-Lower Silurian Longmaxi Fm,involving field survey on the Wuxi and Tianba sections etc.,TOC and gas content testing,fossil identification and fine stratigraphic correlation,the belt from Wuxi to Fuling is believed to share one depositional center,and the shale with TOC＞2％ in the Wuxi area is cumulatively more than 90 m thick.Moreover,in view of the difficulty in the black shale differentiation in the Wufeng-Longmaxi Fms,the typical Well Wuxi 2 in the complex structure area carries out fine shale reservoir zonation according to regional stratigraphy and graptolite zone sequence and then confirms eight graptolite zones from WF2 (Wufeng Fm) to LM9 (Longmaxi Fm).It can be concluded that the biostratigraphy is generally stable in the area,and the qualified shale mainly lies in the graptolite zones from WF2 (Dicellograptus complexus) to LM6 (Demirastrites triangulatus) but shows instability of lateral distribution in the south margin of Dabashan.%要实现我国“十三五”页岩气产量发展目标(2020年年产300×108 m3),亟需寻找新的页岩气勘探开发有利区.四川盆地东部宣汉—巫溪页岩气矿权区块具有良好的页岩气勘探开发潜力,为进一步分析该区上奥陶统五峰组—下志留统龙马溪组海相页岩地层的发育特征,通过对巫溪、田坝等剖面的野外地质踏勘,TOC、含气量等分析化验,古生物化石鉴定和精细地层对比,得出了巫溪和涪陵一带同属一个沉积中心、巫溪地区TOC＞2％的富有机质页岩累计厚度超过90 m的认识.进而针对该区五峰组—龙马溪组黑色页岩层系难以区分的难题,根据区域地层特征和笔石带序列对复杂构造区典型井——巫溪2井的页岩储层进行了精细划带,确定了8个笔石带,即五峰组的WF2笔石带—龙马溪组LM9笔石带.结论认为:该区生物地层基本稳定,优质页岩主要位于WF2(Dicellograptus complexus)-LM6(Demirastrites triangulatus)笔石带,但同时在大巴山南缘优质页岩的横向分布仍存在着不稳定性.
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