STRUCTURAL FEATURES OF THE NORTHWEST SLOPE ZONE OF PENGLAI 19-3 OILFIELD AND THEIR CONTROLLING OVER HYDROCARBON ACCUMULATION

In order to assess the hydrocarbon potential in the northwest slope zone of the Penglai 19-3 Oilfield, well data and seismic data have been collected to study the fracture characteristics, tectonic evolution and reservoir formation history through fault geometry description and tectonic reconstruction. Results show that the trend, dip direction and bonding relation of the NE(NNE)and NW(nearly EW)trending faults are mainly dependant on regional stress and stratigraphic thickness, as well as tectonic positions. As far as the superposition of regional stress is considered, there are three key periods, i.e. pulling apart in early Cretaceous(Yanshanian period), dextral strike-sliping in late Eocene and pulling apart by neotectonic movement from Pliocene to Quaternary. Structural ridges are controlled by pre-existing basement faults in early Cretaceous, which created necessary conduits for hydrocarbon transverse migration. Drive-through type fault on structural ridge developed by neotectonic movement from Pliocene to Quaternary acts as favorable pathways for vertical migration of hydrocarbon. The active stage is also the important hydrocarbon accumulation period in Bohai, suggesting great potential for hydrocarbon exploration.