石油初次运移迹象的判别与生油岩排油能力的讨论

SIGNS OF PRIMARY OIL MIGRATION AND ABILITY OF OIL EXPULSION

作者从石油在运移过程中的“地质色层”作用出发,用一种新的方法——“沥青A、C对比法”进行石油初次运移迹象的判别以及运移层划分;讨论了总烃(HC)以及饱和烃(A1)中不同碳数正构烷烃的运移效率;提出了一个可用于盆地生油岩评价的新指标——比界面积(K)。

The Subei Basin is located in the north of Jiangsu Province, China. Nineteen Paleogene core samples were collected from a well at 3155.67-3205.80 m well in the Subei Basiu for the investigation of primary migration of oils. R0 values and isomerization parameters of hopane and sterane show that the source bed lies within the migration window. In order to determine whether there has occurred primary oil migration, the authors have adopted a novel method-correlation of bitumen A with bitumen C. Studies have demonstrated that bitumens A and C have the same primary composition, and diagenesis and catagenesis have no influence on such a good relationship between them. Bitumens A and C from the middle and lower parts of the source bed, where there is no sign of primary oil migration, show little change in composition, but samples from the uppermost display great changes in composition due to pri-mary migratioh.In this study the thickness of the oil expulsion zone has been determined and a new para-meter, K = S/V or = 2/H(m^(-1)), for assessing source beds is presented as well.