Structural Feature And The Law Of Oil-gas Reservoir Distribution In Middle-north Area Of Huanghua Depression

Huanghua depression is a structurally complicated subbasin formed during Cenozoic in the Bohai Bay basin. The central-north area of Huanghua Depression is the important oil and gas resource replaced region of Dagang oilfiled. It's formation and evolution are similar to other depressions of Bohai Bay basin. It has complicated geological characters and particular geological law because of the peculiar geographical location. The structural geometric, the dynamics machine of structural evolution and the control of the structure on the distribute of oil and gas in the central-north area of Huanghua Depression have been studied by the method of structural analysis based on the seismic and drill information with the guide of the theory of tectonic activity. The study indicates that this area have extensional structures style and strike-slip structural style. Between these two styles, the extensional structures style is predominant. The NE extensional structures style and NW transverse accommodation zone form structural framework of this region. The main faults have the characteristics of large scale, long term development, similar shape in main activity stage, and communication with oil sources. The fault activities of Cenozoic have apparent phase and migration. The diversity of fault activities creates different structural evolution history. This region of Cenozoic is formed by lateral strike slip pull-apart movement thoughting analyseis of regional tectonic background and basin large-scale structural deformation. The main faults control the distribution of source rock. The activities of faults control the distribution of reservoir. The sedimentary center of basin has the trend of migrating from south to north and from west to east. The multi-period activities of fault control special source reservoir caprock assemblage. The multi-period fault movements form numerous traps. The fault activities control oil and gas migration direction. The phase of fault activities makes the reservoir separate into lower play (Es3), middle play (Es1 and Ed) and upper play (Neocene). The migration of fault activities make the petroliferous horizon have the trend of becoming new from south to north and from west to east. The Dongying formation and Neocene of the Baidong structure belt and Nanpu structure belt are the next main exploration direction on the foundations of these the fault is the main-controlling factor of oil-gas distribution and sedimentary center migration regulation of Huanghua depression.