Characteristics of Natural Gas Sources and Accumulation in Dibei Uplift of Junggar Basin
准噶尔盆地滴北凸起天然气来源及成藏特征

The large-scale gasfield, containing many gas reservoir layers mainly composed of Carboniferous volcanic rocks, is discovered in the Dinan uplift-the south of Dishuiquan depression in central Junggar basin. Dibei uplift, near the Dishuiquan depression in south and Wulungu depression in north, is considered as the favorable region of hydrocarbon accumulaion from two depressions. Recently, small\|scale gas reservoirs have been found in Jurassic and Carboniferous strata, but no greater breakthrough has been made. It is still unclear about the origin of the natural gas of the Dibei uplift. By comparing with carbon isotope of natural gas and reservoir extraction of gas intervals, it is showed that the geochemical characteristics of natural gas in Dibei and Dinan uplift has significant differences, and natural gas of Dibei uplift is similar with that from typical Carboniferous sources in the eastern part of the basin. Consequently, the natural gas should be sourced from Wulungu depression whose geochemical characteristics of rocks in Carboniferous are similar with Dibei uplift. Based on the characteristics of fluid inclusions, it is concluded that the gas is accumulated at late stage of late Cretaceous.