中国渤海湾北部凝析油的特征和成因

THE CHARACTER AND GENESIS OF CONDENSATE IN THE NORTH OF LIAODONG BAY, CHINA

The JZ20-2 structure located in the north of Liaodong Bay is rich in con-densate. The normal crude oil generally exist beneath the condensate. There is no resin and asphaltene in the condensate, but 57% chain alkane and 35% cycloal-kane exist in light fraction ( C<10 ) . GC-MS analysis shows that sesquiterpane and tricyclic diterpanes are very abundant. The composition of the condensate indicates that the precursor is the mixture of continental plants and algae. The gas includes condensate gas, dissolved gas and a small amount of free gas. These gases are the associated ones of the condensate oil. According to the correlation of biomarkers, the condensate comes from the high mature mudstone in the Liao-zhong depression in the east of this structure. The type of organic matter may be the sapropel-humics. The condensate in the JZ20-2 structure indicates that the condensate may be formed in the different mature stages. The source rock which contains the humic organic matter can generate condensate in the stage of R0 = 1.0 ~ 1.3.