Faults are the main oil-gas migration pathways in Chepaizi area and can also form associated hydrocarbon re-servoirs

thus research on fault sealing ability is of great significance for confirming spatial distribution of reservoirs in the study area.Through qualitative analysis of fault characteristics and the timing between faulting and hydrocarbon generation and expulsion

and quantitative evaluation of factors controlling sealing ability such as juxtaposition of lithology

shale smear

and normal stress on fault surface

we studied the sealing ability of two major faults(F1 and F2)in northeastern Chepaizi Uplift

and performed comprehensive judgment by using fuzzy evaluation method.The results show that the sea-ling abilities of F1 and F2 feature in ‘vertical periods and lateral segmentation’.Vertically

the fault sealing ability can be divided into periods

including Cretaceous(K)

the first member of Neogene Shawan Fm (N

1

s

1

)

2

nd

member of Neogene Shawan Fm(N

1

s

2

)

and 3

rd

member of Neogene Shawan Fm(N

1

s

3

).The sealing ability of faults in Cretaceous is good as a whole except for the southern segment of F2.For N

1

s

1

sealing ability of F1 is good in the northern segment

poor in the middle segment

and good to poor in the southern segment

while that of F2 is poor to fair as a whole.For N

1

s

2

fault sealing abilities are good as a whole.For N

1

s

3

fault sealing abilities are poor as a whole

except for the middle segment of F2 whose sealing ability is good.