Discovery of Upper Paleozoic marine shale gas in the western part of the Lianyuan Depression (Well XXY-1), central Hunan, China

1.Objectives Lower Paleozoic shale gas in southern China has been comprehensively explored over the past few decades(Zhai GY et al.,2018;Bao SJ et al.,2018).Many gas fields targeting Wufeng-Longmaxi Formations in the Sichuan Basin,including Changning,Weiyuan,and Fuling gas fields,have been discovered and commercialized(Zhai GY et al.,2018;Meng FY et al.,2020).Moreover,breakthroughs have been made in shale gas from the Silurian,Cambrian,and Sinian in the Yichang area,revealing a tremendous potential for shale gas exploration in the Lower Paleozoic of southern China.Although there is much organic-rich mud shale of Upper Paleozoic erathem in southern China,especially in central Hunan,their contributions to shale gas resources are unknown.