Abstract: Bohai Sea area experienced a complex tectonic evolution history including the multi-stage extension which led to the development of a complicated abutting faults system. Although the formation of abutting faults has been demonstrated to contribute significantly to the hydrocarbon accumulation in the fault block traps, while strong hydrocarbon productivity heterogeneity has appeared in lots of drilling practices, and hydrocarbon leakage was the main cause for some drilling failure. Comprehensive analyses and comparisons combining the 3D seismic, well data, and analogue modeling reveal that three factors are related to the sealing ability of abutting faults: (1) the evolution level of abutting faults determines the degree of leakage in fault intersection; (2) the time interval between charge and leak controls the effective charging timing; (3)difference in stress among faults resulted from oblique extension of pre-existing faults determines the ability of stress sealing. The height of trapped hydrocarbon column derived from drilling data in the structures with abutting faults of Bohai Oilfield shows excellent correlation with the sealing ability analysis based on the above three factors, demonstrating that this method has good application prospects in petroleum exploration in areas with similar structures.

Key words: multi-stage extension, abutting faults, sealing ability, time interval between hydrocarbon charging and leakage,
oblique extension, Bohai Sea