Research on gas reservoir characteristics of Triassic dense sandstone in Tun 1 well of Yichuan basin and its reservoir forming conditions analysis

Located in the low position of Yichuan nose-like structure of Yichuan basin,Tun 1 well reveals that the upper dark formation of Triassic system is about 1400m,with the characterisitics of 612m developed effective source rock.The drilling results indicate rich hydrocarbon shows and have the characteristics of big span,long interval and continuous oilbearing.Fracturing testing on the lower part of upper Chunshuyao formation acquired daily commercial flow of 7 200 m3,which revealed the prelude of unconventional oil and gas exploration in Yichuan basin,surrounding areas and southern North China.The analysis results show the gas reservoir in Chunshuyao formation is a dense gas reservoir and has the characteristics of abnormal low pressure,no bottom water and not controlled by structure,which can provide significant guidance for oil and gas exploration in western Henan province and its adjacent regions.