Organic geochemistry of Lower Jurassic source rocks in Xining Basin

A set of Lower Jurassic source rock was found in the Xining Basin, Northwestern China. In order to investigate the potential of hydrocarbon generation and the possibility of shale gas and oil formation, the samples in the Lower Jurassic outcrop section of Dachashilang District were collected to measure the abundance, type, and maturity of the organic matters in the lacustrine and HST peat-charcoal shales. The results show that the lacustrine dark shales have the high abundance of organic matter, which are fallen into the area of general-good source rock; the carbonaceous shales have the poor organic matter, which are located within the area of poor-average source rock. Both lacustrine shales and HST carbonaceous shales are III1 type of kerogen which is prone to gas. The vitrinite reflectance values are in range of 0.7%-0.94%, suggesting it would be mature stage for massive hydrocarbon generation. The organic geochemical feature for the Lower Jurassic share is similar with the major shale gas reservoirs in the world. Thus, we suggest that the Riyueshan Formation source rock in Xining Basin would be potential for conventional and unconventional oil and gas exploration.