粘土矿物在油气初次运移中作用的探讨

本文在大量实际分析资料基础上,总结出我国含油气盆地中蒙脱石的转化类型,并讨论了它们在油气初次运移中的作用。在蒙脱石向伊利石连续转化型的盆地中,矿物转化对初次运移有明显作用;在蒙脱石向伊利石不连续转化或少量转化类型盆地中,由于矿物转化与生油期不相匹配或可转化的蒙脱石含量太少,对初次运移的作用不明显;在蒙脱石无转化和缺少蒙脱石的盆地中,基本不存在蒙脱石的转化过程,因而对初次运移不起作用。

DISCUSSION ON THE EFFECT OF CLAY MINERALS IN PRIMARY MIGRATION OF PETROLEUM

On the basis of analyzing clay minerals of more than 8, 000 shale samples collected from 20 oil-bearing basins, we summarize six transformation types of smectite in Chinese oil-bearing basins: I .Continual conversion type from smectite to illite; H .Noncontinous conversion type from smectite to illite; Ⅲ.Conversion type from smectite to chlorite; Ⅳ. Conversion type from minor smectite to illite; V . Nonconversion type of smectite and Ⅵ.Smectite-absent type.We discuss different effects of these types on the primary migration of petroleum in this paper.First of all in the basin of continual conversion type, the mineral transformation does obvious effect to the primary migration.For in this kind of basin.the dehydration stage in the conversion from smectite to illite corresponds to the stage of the primary migration of petroleum. When organism transform into petroleum, the mineral smectite coexisted with organism transforms into interstratified illite / smectite-and furthur illite.The shale microfractures emerged in the process of transformation provides channel for the primary migration of petroleum. The dehydrated water in this process contributes as a carrier and the unusual high presure produces power to the primary migration. Whearas, the second, in the basins of noncontinous conversion or non-conversion type, the effect is not obvious, since mineral tranformation does not match with the stage of petroleum generation or there is not enough transformative smectite. And the third, if there isn't smectite's transformation or smectite itself in the basins, the trans formation and dehydration of smectite seldom occur.Conseouently.there is no effect of clay minerals on the primary migration.