准噶尔盆地沙湾凹陷周缘上古生界天然气地球化学特征及成因研究

针对准噶尔盆地沙湾凹陷周缘上古生界天然气成因与来源认识不清的问题,运用烃源岩热解气模拟实验技术,根据热解气碳同位素分布,结合天然气组分、碳同位素、轻烃组成及伴生原油地球化学特征,揭示了沙湾凹陷周缘上古生界天然气成因与来源.研究结果表明:研究区天然气具有6种成因类型,Ⅰ类天然气来源于佳木河组烃源岩,δ13 C2值大于-2...

Study on Geochemical Characteristics and Genesis of Upper Paleozoic Natural Gas in the Perimeter of Shawan Sag,Junggar Basin

To address the problem of poor understanding of the genesis and source of the Upper Paleozoic natural gas in the perimeter of Shawan Sag,Junggar Basin,the simulation and experiment of source rock pyrolysis gas were conducted to work out the genesis and sources of the Upper Paleozoic natural gas in the perimeter of Shawan Sag based on the carbon isotope distribution of pyrolysis gas,as well as the natural gas components,carbon isotopes,light hydrocarbon composition and geochemical characteristics of associated crude oil.The results showed that there were six types of gas genesis in the study area.TypeⅠnatural gas was derived from the source rocks of Jiamuhe Formation with aδ¹³C₂ value greater than-26.0‰;TypeⅡnatural gas was biogas with negativeδ¹³C₁ value and extremely high aridity coefficient;TypeⅢnatural gas was derived from the source rocks of Jiamuhe Formation and the source rocks of Lower Wuerhe Formation,with an aridity coefficient of greater than 0.95,andδ¹³C₂ value of about-26.0‰;TypeⅣnatural gas was derived from the source rocks of Lower Wuerhe Formation,withδ¹³C₂ value ranging from-27.5‰to-26.9‰;TypeⅤnatural gas mainly originated from the source rocks of Lower Wuerhe Formation and Fengcheng Formation,among which,the natural gas with aδ¹³C₂ value of not less than-29.0‰was from Lower Wuerhe Formation and the natural gas with aδ¹³C₂ value of less than-29.0‰was mainly from Fengcheng Formation;TypeⅥnatural gas originated from the source rocks of Fengcheng Formation with aδ¹³C₂ value of less than-31.0‰.There are three types of effective gas source rocks in the study area,including humic source rocks of Permian Jiamuhe Formation,humic source rocks of Lower Wuerhe Formation and sapropelic source rocks of Fengcheng Formation.The study results give a answer to the gas source problem of the Upper Paleozoic in the perimeter of Shawan Sag,and provide a basis for the study on natural gas exploration and reservoir accumulation in the study area.