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针对准噶尔盆地目前勘探程度相对较高的玛湖凹陷北部—乌夏断裂带天然气特征变化较为复杂的实际,通过天然气赋存特征、天然气与相关烃源岩有机地球化学特征的详细分析,对天然气的成因与来源进行了系统的研究。研究发现,该区已有的天然气主要为原油溶解气,少量气层气主要分布在乌夏断裂带的中生界,为原油溶解气溢出而形成的浅层气。天然气以烃类化合物为主要组分,二氧化碳与氮气等非烃含量相对较低。天然气干燥系数介于0.66~0.99之间,主要为湿气,少数干气主要分布在较浅的部位,是运移分异作用较强、保存条件较好的结果。天然气成因类型主要为腐泥型和偏腐泥型的过渡型,未见腐殖型天然气。气源分析表明天然气主要来自风城组湖相腐泥型—混合型母质的烃源岩,乌尔禾组腐殖型母质烃源岩有少量贡献,佳木河组腐殖型母质烃源岩对玛湖凹陷北部斜坡区断裂发育部位的局部天然气有贡献。
In view of the fact that the natural gas characteristics in the northern part of the Mahu Sag, the relatively unexplored exploration area in the Junggar Basin, are complicated, the natural gas characteristics and the organic geochemical characteristics of natural gas and related source rocks are analyzed in detail. The causes and sources of a systematic study. The study found that the existing natural gas in the area is mainly crude oil dissolved gas, and a small amount of gas is mainly distributed in the Mesozoic in the Wuxia fault zone, which is the shallow gas formed by the overflow of crude dissolved gas. Natural gas is dominated by hydrocarbon compounds, with relatively low levels of non-hydrocarbons such as carbon dioxide and nitrogen. Natural gas drying coefficient is between 0.66 ~ 0.99, mainly moisture, a few dry gas is mainly distributed in the shallower parts, is the result of strong migration and differentiation, better storage conditions. Types of natural gas are mainly sapropel and sapropelic transition type, no humus-type natural gas. Gas source analysis shows that natural gas mainly comes from the source rock of the sapropelic-mixed parent material of the Fengcheng Formation and a small contribution to the humoral parent source rock of the Wuerhe Formation. The humus parent source rock of the Jiamuhe Formation Contribute to the local natural gas in the fault development site in northern slope of Mahu depression.