Identification and geological significance of clustered bioherms and shoals in the Permian Changxing Formation, central Sichuan Basin

The Permian bioherms and shoals are the efficient petroleum exploration targets of Sichuan Basin in the Upper Yangtze Block. This study delineates the clustered bioherms and shoals developed in the interior Pengxi-Wusheng (PX-WS) Sag interior and its adjacent highlands in central Sichuan, utilizing seismic and drilling data. This discovery breaks the conventional understanding that the Permian bioherms are predominantly limited to the platform margins flanking the trough in Sichuan. As for Changxing Formation (Fm.), the bioherm dominantly exhibits mound-shaped structure and chaotic seismic reflection, while the shoal is characterized by weak layered reflection. The bioherms are distributed in large-scale clusters, extending from NW to SE in a multi-stage stacking configuration. Paleogeomorphic reconstruct-tions of high-precision seismic data reveal that their tectonic origin is closely related to the Permian uplift of the Dongwu Movement and the breakup of the Pangea supercontinent. Recent drilling results from Well P10 have substantiated the reliability of identifying bioherm and shoal gas reservoir in platform interior. Distinguish from traditional distribution, this research demonstrates that clustered bioherms and shoals in intra-platform represent a highly prospective domain for petroleum and gas exploration of Changxing Fm. in the Sichuan Basin.