A Study on Hydrocarbon Generation Capacity of Graptolite in Marine Hydrocarbon Source Rocks in Southern China

The common development of graptolite in marine shale of Southern China has a close relationship with the formation of marine shale gas, but whether graptolite has hydrocarbon generating ability of shale gas has not been directly confirmed by relevant experiments. In this study, pure graptolite from black graptolite shale was selected and the graptolite sample was hand-picked for the experimental study on pyrolysis hydrocarbon generation. The results show that the graptolite is a good parent material. The carbon content of the graptolite is high, accounting for most carbon sources of graptolite shale. The main products of pyrolysis hydrocarbon generation are shale gas and light oil, which accounts for more than 94% of the total hydrocarbon generation products, whereas the shale gas accounts for 54%. The pyrolysis product is similar to that between type-Ⅲ organic matter (OM) and type-Ⅱ OM is more similar to that of type-Ⅲ OM, which is mainly gaseous hydrocarbon products. The hydrocarbon generation ability of graptolite may be higher during thermal maturation process, which is closely related to the genesis of widespread shale gas in Southern China at present.