DYNAMIC MODELS OF PETROLEUM MIGRATION AND ACCUMULATION FOR PALEOZOIC-PROTEROZOIC BURIED HILLS IN JIZHONG DEPRESSION, BOHAI BAY BASIN

doi:10.3321/j.issn:1000-2383.2001.01.011

Abstract：The comprehensive analysis of fluid pressure field, fluidchemical field and fluid-migrating conduits of buried hills in Jizhong depression, Bohai Bay basin classifies the buried hills as the following three major dynamic categories of petroleum migration and accumulation: (1) unconformity-connected-open buried hills (Type Ⅰ)，(2) fault conduit-semi-open/semi-closed buried hills (Type Ⅱ)， and (3) closed buried hills (Type Ⅲ). Type I buried hills are connected with the regional underground hydrodynamic system located in the middle part of the Jizhong depression where is present a sufficient supply of the petroleum and gas that may result in the formation of large-scale hydrocarbon pools in the buried hills. Type Ⅱ buried hills occur in the slopes close to the hydrocarbon-generated sags, with the seismic pumping conduits in the buried hill-associated faults serving as the acting force on the petroleum and gas migration and accumulation, exhibiting an excellent condition for the petroleum pools. Type Ⅲ buried hills scattered within the depression zone with a relatively great degree of subsidization occur separately and are overlapped by the Tertiary abnormally high pressure zone, restraining the acting force of the fluid conduits associated with the buried hills. In this case, the buried hills in the closed system with the relatively poor condition of petroleum and gas migration and accumulation may accommodate small-sized petroleum and gas pools of the buried hills with great exploration risks.