Abstract: Based on the comparison of hydrocarbon accumulation conditions of inner buried hills among the Huanghua depression, Jizhong depression and Liaohe depression, the exploration potential of the inner buried hills of Cambrian to Meso-Neoproterozoic in the Huanghua depression, Bohai Bay Basin, was analyzed, and its exploration direction has been confirmed. The study results indicate that the Cambrian to Meso-Neoproterozoic in the Huanghua depression has lower exploration degree, the inner buried hill has good geologic conditions for hydrocarbon accumulation, with various types of buried hills and extensive distribution area, thus it is a much favorable exploration region. By evaluating the major traps of the Huanghua depression, it is concluded that the favorable (type I) traps accounts for 48% of the total trap area, and are chiefly distributed in the Qikou sag; they have the favorable conditions for forming large-scale reservoirs in inner buried hills. Especially, most traps are distributed in trough regions, with better developed deep-large faults, then the high-quality dolomite reservoirs in Cambrian to Meso-Neoproterozoic and the major source rock in the third member of the Shahejie Formation (Es3) can connect laterally, thus larger inner buried hill reservoirs with hydrocarbons being generated in younger strata and stored in older strata can be formed. Therefore, it is proposed that the No.1 trap (the Yangerzhuang buried hill) in the Yangerzhuang buried hill belt is the preferred exploration risk target.

Key words: exploration potential, inner buried hill, hydrocarbon accumulation condition, Cambrian to Meso-Neoproterozoic, Huanghua depression, Bohai Bay Basin