Evaluation and Potential Analysis on Upper Carboniferous Hydrocarbon Source Rocks in Shihuigou Area of the Eastern Qaidam Basin

The Upper Carboniferous hydrocarbon source rocks were developed in the Shihuigou area of the eastern Qaidam Basin.Due to the lack of downhole source rock evaluation,its hydrocarbon genetic potential was not yet clear.Based on the analysis of organic matter abundance,type and maturity of downhole hydrocarbon source rocks and combined with oil-source correlation and distribution of source rocks,the hydrocarbon genetic potential was comprehensively evaluated.The results show that dark mudstone and carbonaceous mudstone are relatively high organic matter abundance and belong to moderate-good source rocks,and their organic matter is mainly types Ⅱ and Ⅲ with higher hydrocarbon-generating potential,marine limestone belongs poor-moderate source rock,and its organic matter is mainly types Ⅰ and Ⅱ with certain hydrocarbon-generating potential.Organic matter of upper Carboniferous hydrocarbon source rocks is at the stage of mature to high-mature evolution,it is at the stage of high hydrocarbon generation and expulsion.The oil-source correlation indicates that the crude oil of oil-bearing limestone is generated from Carboniferous hydrocarbon source rocks,it is proven that its hydrocarbon generation is effective.Meanwhile,it is revealed by outcrops and well drilling data and previous study that the upper Carboniferous hydrocarbon source rocks are widely distributed with large thickness in the Shihuigou Area of the eastern Qaidam Basin,it has good prospects for petroleum exploration.