The area around central Bohai Bay is an important prolific zone

where faults are well developed and faulting during the neotectonic movement played a significant role in migration and preservation of hydrocarbons.The fault activity rate (FAR) method was used to study the relationship between faulting activity and hydrocarbon accumulation/preservation in the area based on analysis of activity changes along the strike of main fault and combinations of faults with different FAR within the zone.In addition

the controlling mechanisms of hydrocarbon accumulation were also discussed in respects of the locations of spill points

the definition of fault carrier systems and FAR

and the relationship between fault throw and thickness of regional caprock.The results indicate that hydrocarbon accumulations in the area are mainly located near faults with moderate or weak activities(FAR<25 m/Ma)

while they seldom occur near faults with strong activities(FAR>25 m/Ma) because these faults served mainly as vertical migration pathways

making it hard to form shallow oil accumulations.For these faults

only in areas with relatively weak fault activities can hydrocarbon accumulation occur.