Geochemical characteristics of the shale gas reservoirs in Guizhou Province, South China

We analyzed a large amount of published petrological, mineralogical, and geochemical data from the Niutitang, Wufeng-Longmaxi, Dawuba, Liangshan, and Longtan organic-rich shales. These include marine shales and marine-continental transitional shales. The main marine organic-rich shales include the Niutitang, WufengLongmaxi, and Dawuba shales, while the main marine-continental organic-rich transitional shales include the Liangshan and Longtan shales. The marine organic-rich shales were generally deposited under anoxic conditions, and are generally brittle siliceous-rich lithofacies, which is a type I organic-matter dominated. In contrast to the marine organic-rich shales, the marine-continental transitional organic-rich shales were most likely deposited under dysoxic to oxic conditions. They are generally less brittle argillaceous-rich lithofacies, that are type III organic-matter dominated. Of the five organic-rich shales, the Niutitang and Wufeng-Longmaxi organic-rich shales are over-mature shales, and the Dawuba, Liangshan, and Longtan organic-rich shales are high-maturity to over-mature shales. The spots with siliceous rock floor on the western edge of the Xuefeng uplift is a favorable area for future exploration of shale gas in the Niutitang organic-rich shale. The Chishui terrestrial basin and center of the aulacogen are the faverable areaa for shale gas expolation and development of the WufengLongmaxi and Dawuba organic-rich shales, respectively. More basic geological research work is needed to select favorable areas for the Liangshan and Longtan organic-rich shales. To accurately guide future shale gas exploration and development, more research is needed on the relationship between the sedimentary environment, the lithofacies, and the reservoir properties of the shales.