Since it is risk to implement scheme of deep water fault block reservoir development，Sangos oilfield of west Africa is taken as an example. Based on the reservoir geological modeling process，well logging，seismic and dynamic data were used comprehensively for the quantitative evaluation of fault seal. Firstly，salt diapir and salt piercing were identified here as two main fault modes which are salt related structure. Secondly，according to the characteristics of tectonic and sedimentary，shale smear was thought to be the main control factors of fault sealing and its three parameters（SSF，CSP，SGR）were analyzed and compared，and CSP and SGR were finally used step-by-step to calculate the transmission multiplier for each fault based on grid model. Finally，the concept of fault connectivity was defined as a quantitative and reasonable parameter of fault evaluation，and it was used to characterize the transmission capacity of each fault. The research shows that：the connectivity of five faults can be ordered as F5>F4>F3>F2>F1，and F1 is sealing completely. The research result is validated by the actual dynamic data of subsequent development wells.