吐哈盆地水溶气组分与同位素特征形成机理及意义探讨

测量了吐哈盆地 6个水溶气样品的组分和碳同位素值,并通过与盆地天然气的对比,探讨了水溶气组分及碳同位素特征形成机理及其应用的可能性。水溶气基本受制约于烃类气体溶解度的特征,与盆地天然气应属同源,但二者也存在明显的差异,如C1/C1～ 5值水溶气应大于天然气,实际反而较小,甲烷同系物碳同位素均较天然气富集-6 C。作者认为这些特征的形成与水溶气的溶解量小于扩散运移量相关,并认为水溶气与天然气组分和同位素差异的大小可用于探讨采样层位与天然气动态成藏体系关联的紧密程度。

A Discussion of Formation Mechanism and Its Significance of Characteristics of Chemical Composition and Isotope of Water-dissolved Gas in Turpan-Hami Basin

The chemical composition and carbon isotope of the six water-dissolved gas samples in the Turpan- Ha-mi basin are measured and the characteristic of formation mechanism and the possibility of application of the com-position and isotope to natural gas geology are discussed by comparison with the natural gas in the basin. The char-acteristic of the composition of the water-dissolved gas hydrocarbons is mainly controlled by dissolution degree of the hydrocarbons. They are derived from the same source rocks as the natural gases, but they are different from the natural gases, e. g., the C ₁/C _{1 ～ 5} of the water-dissolved gas should be higher than that of the natural gas, but in fact it is lower; the homologue of the water-dissolved gas CH ₄ is enriched in13C than that of the natural gas. the above characteristic was thought to be related with that the dissolved content of the natural gases in the dis-solved-water was less than the migrated content. It is considered that the differences of the composition and isotope between the water-dissolved gas and the natural gasindicate the relation of between the sampling membersand nat-ural gas dynamics pool-forming system.