Abstract:

The basic method  in studying petroleum accumulation system  in superimposed basins was demonstrated by a case
investigation  in petroleum  reserviors of  the central Junggar Basin. The method can be summarized  into  two points. The  first  is
that  the study  is  focused on petroleum reserviors. The second  is  that both organic and  inorganic geochemical methods are used.
The case study  in  the central Junggar Basin shows  that  the area has at  least  two petroleum accumulation systems according  to
the organic (biomarker in particular) studies, i.e., the Permian system in the eastern area to the Penyijingxi sag, and the Permian
and Jurassic system in the middle-eastern Mosuowan area. The study using inorganic geochemical method on reservoir diagenetic
calcite shows  that  the area has  two additional petroleum accumulation systems,  i.e.,  the Permian and Jurassic system  in  the
surrounding area of the Dongdaohaizi sag and the Permian system in the Shidong area. Moreover, the potential of retaining oil and
gas  for each petroleum accumulation system was assessed  to provide  information  for  the exploration. Therefore,  it  is concluded
that the research method of petroleum accumulation system can help to improve the guidance on petroleum exploration, and the
organic and inorganic geochemical methods are complementary to each other. In particular, the new application of the inorganic
geochemical method is a supplement to and improvement for the previously and commonly used organic geochemical method, and
thus deserves to be studied further.

Key words: petroleum accumulation system, superimposed basin, organic and inorganic geochemistry, central Junggar Basin