Abstract: BZ29-4 oilfield in Bohai is a medium-sized complex fault block with multiple layers.Reservoir hydrocarbon analysis shows that BZ29-4 oilfield was formed after deposition period of lower member of Minghuazhen formation,and oil and gas mainly comes from source rocks in the 3rd member of Shahejie formation,secondly from1 st and 2nd member of Shahejie formation.Natural gas from Minghuazhen formation is primarily biodegradation gas,and Paleogene natural gas is oil-type gas associated with oil,with a multi-stage charging characteristic.Hydrocarbon migration system has an obvious control on oil and gas distribution,hydrocarbon migration of downthrow block is controlled by fault,rich accumulation in faulted-stage zone and salient zone is controlled by favorable channels coupled with fault and sandbody.BZ29-4 oilfield exploration process showed fine description of migration channels is an effective means for finding hydrocarbon in complex faulted zone.