Geological Characteristics of Shale Gas in Different Strata of Marine Facies in South China

In the Middle and Upper Yangtze region of South China, there are well developed sets of marine shale strata. Currently only Wufeng Longmaxi shale gas has been developed in scale, while the Sinian and Cambrian shale gas are still under exploration. The various shale strata show different characteristics in lithological features, such as lithofacies types and reservoir physical properties, which are due to the influence of tectonic pattern, sedimentary environment, and diagenesis caused by tectonic subsidence. This will affect the later fracturing technology and fracturing effect. The shale reservoirs of Sinian doushantuo, Cambrian Niutitang, Upper Ordovician Wufeng, and the Lower Silurian Longmaxi Formation shale were evaluated and compared with each other with respect to their sedimentary environments, lithofacies, minerals compositions, and micro pore characteristics. The reservoir characteristics of the shale and the main control factors of shale gas enrichment were summarized in this study.