Petroleum origin and source in Shidong area, Junggar Basin

Shidong area locates in the west of the Dishuiquan Sag of the Junggar Basin,adjacent to the Shixi oil field(with 10⁸ treserves) and the Kelameili gas field(with 10¹¹m³ reserves).High-yielding oil-and-gas flows have been found in the region;however,production scale is small and the origin and source of petroleum are not clear yet.The whole-hydrocarbon geochemistry method has been practiced in petroleum source analyses.The dry coefficients of natural gas in Shidong area are high,and the carbon isotopes of methane and ethane are heavy,which is different from those in the Shixi oil field and similar with those in the Kelameili gas field.Crude oils from both deep and shallow formations in Shidong area have the same characteristics basically.Carbon isotope,pristane/phytane ratio,chromatography-mass spectroscopy of light and saturated hydrocarbon of crude oil in Shidong area are not the same as those in the Shixi oil field,and similar with those in Jurassic of well Lunan1 region around the Dishuiquan Sag and those in the Kelameili gas field.The studies have indicated that the petroleum in Shidong area comes from the Dishuiquan Sag rather than the Shixi oil field.