ORGANIC GEOCHEMISTRY OF THE SOURCE ROCKS OF LOWER JURASSIC WUDANGGOU FORMATION IN SHIGUAI BASIN, INNER MONGOLIA

Dark mudstone and shale of Lower Jurassic Wudanggou Formation are well developed in the Shiguai Basin in Inner Mongolia. Based on geological exploration, typical profile survey, sampling and experimental analysis, the organic geochemical studies are conducted in the aspects of organic matter abundance, kerogen types and maturity of organic matter to evaluate the hydrocarbon potential. The total organic carbon (TOC) contents of the Lower Jurassic hydrocarbon source rocks of Wudanggou Formation range from 0.7% to 12.4%, corresponding to organic matter type of Ⅱ₂-Ⅲ. The vitrinite reflectance is between 0.47% and 0.71%, indicating that the hydrocarbon source rocks mostly achieved low mature stage of evolution. The Wudanggou Formation is the important hydrocarbon source rock in the central area of Inner Mongolia, with potential of unconventional energy of shale gas.