Tectonic evolution and accumulation characteristics of Carboniferous shale gas in Yadu-Ziyun-Luodian aulacogen, South China

The Yadu-Ziyun-Luodian aulacogen (YZLA) developed into being NW-trending in the Late Paleozoic, and was considered as an important passive continental margin aulacogen in Guizhou, South China. This tectonic zone is a large intracontinental thrust-slip tectonic unit, which has undergone a long period of development. It was finally determined in the Yanshanian, where the typical Upper Paleozoic marine shales in China were deposited. In 2021, well QSD-1 was deployed in the Liupanshui area at the northwest margin of the trough, and obtained a daily shale gas flow of 11,011 cubic meters in the Carboniferous Dawuba Formation, which achieved a breakthrough in the investigation of shale gas in the Lower Carboniferous in South China, and revealed the good gas-bearing properties and broad exploration prospects of the aulacogen. Being different from the Lower Paleozoic strata in the Sichuan Basin and the Yichang area of the Middle Yangtze, the development of the Carboniferous Dawuba Formation in the aulacogen exhibits the 3 main characteristics. Comparative analysis suggests that the area covered by the current Triassic strata has a low degree of destruction and good conditions for shale gas preservation, which can be regarded as the favorable area for the next exploration.