Abstract: Nanyi fault block in Gangzhong oilfield is a complex fault block reservoir controlled by structure and lithology, which has entered the high water cut development period and has the characteristics of vertical coproduction and co-injection, serious inter-layer interference and uneven sand body use. Due to well conditions and ground conditions, most of the main sand bodies have stopped production, and the fault blocks were in the stage of low-speed and low-efficiency development. Since 2012, combined with the results of reservoir fine description, the fine study of the structure was carried out and the remaining oil distribution of single sand body was studied through reservoir modeling. Through well pattern reconstruction and fine injection-production control measures, the potential exploration of residual oil was conducted. The results show that the daily oil production of fault blocks increases from 29.40 t to 126.40 t, the annual oil production increases from 1.19×10~4 t to 4.53×10~4 t, the recovery rate increases by 12%, and the recoverable reserves increase by 82.00×104 t.