Biostratigraphy and reservoir characteristics of the Ordovician Wufeng Formation-Silurian Longmaxi Formation shale in the Sichuan Basin and its surrounding areas, China

WANG Hongyan,SHI Zhensheng,SUN Shasha

Fig. 4. Composition and characteristics of graptolite zones in the Longmaxi Formation of Sichuan Basin and its surrounding areas. (a) Cephalograptus cometa, Well JY1, LM7; (b) Lituigraptus convolutus, Well JY1, LM7; (c) Stimulograptus cf. sedgwickii, Well W204, LM8; (d) Lituigraptus convolutes, Well W202, LM7; (e) Lituigraptus convolutus, Well W204, LM7; (f) Torquigraptus decipiens, Well YJ1, LM7; (g) Oktavites sp., Well WX2, LM9; (h) Stimulograptus sedgwickii, Well WX2, LM9; (i) Spirograputs guerichi, Well WX2, LM9; (j) Spirograptus gurichi, Well W202, LM9; (k) Torquigraptus planus, Well WX2, LM9.