关键词: 下白垩统, 烃源岩, 油气潜力, 中国东南部

Abstract:

By detailed field survey and organic geochemical analyses including organic matter abundance, type, and maturity of
the Lower Cretaceous strata  in  the coastal Southeast China,  the source rock  features of  the strata were obtained. These  features
allow a discussion on the hydrocarbon resource potential of the strata. The results demonstrate that there are in general two sets
of argillaceous hydrocarbon source sequences, i.e., the early Lower Cretaceous represented by the black mudstone of the Bantou
Formation  in Fujian Province and  the  late Lower Cretaceous represented by  the black mudstone or calcareous mudstones of  the
Guantou Formation in Zhejiang Province. The organic matter abundance of the sources reached the moderate to good quality by
the hydrocarbon source rock standards, and  the average TOC values and  the chloroform bitumen “A” of  the early stage sources
are high. The  type of organic matter  is mainly Type  III, Types  II and  I can also be  found and generally  the  types of  late stage
sources are better  than  those of early stage sources. The  thermal maturity of most samples  is high  to over mature, and organic
matter  that was not significantly affected by volcanism  is still  in maturing stage. Thus, a  relatively comprehensive hydrocarbon
resource evaluation indicates that the favorable regions are the northern Guangdong Province for the early Lower Cretaceous, andthe coastal region of Zhejiang Province and the western Fujian Province for the late Lower Cretaceous. These results may provide
new petroleum targets for oil-gas exploration in Southeast China.

Key words: Lower Cretaceous, source rock, hydrocarbon resource potential, Southeast China