| On the basis of previous results, directed by the hydrocarbon accumulation theory, the characteristics of source rock, oil-source correlation, the migration sysytem and the direction of oil migration in Puwei sag is researched. And the petroleum accumulation process is recovered by simulating the hydrocarbon generation and expulsion histories associated with the analysis of the stages of hydrocarbon accumulation and the reservoir forming dynamic. The reservoir forming systems of Puwei sag are divided and the dynamic hydrocarbon accumulation models are set up in this paper.Through systematic sampling and geochemical analysis the geochemical characteristics of source rock and oil are clearly and the spatial relationship between them has been established. The oil and gas discovered mainly distributes in Puwei sag area and adjacent structure zones. The oil can be divided into three types of Puwei sag, neighboring sags and mixed type based on the characteristics of geochemist and distribution. The oil of Es3 distributed in the west wing of Puwei sag, Guyunji slope and the east wing of Puwei sag is Puwei sag type. The oil of middle and lower Es3 distributed in the east wing of Pucheng faulted anticline and Pucheng-nan structure Wenbei fault block zone is neighboring sags type and comes from Pucheng-Qianliyuan sag. The oil distributed from Weicheng horst to Wenmingzhai area is mixed type. The oil from Es2 to Es1 in whole area, the oil of middle Es3 distributed in Pucheng faulted anticline axis part and upper Es3 in Pucheng faulted anticline zone are mixed type too. The mixed oil of west comes from Puwei and Mazhai sag. The mixed oil of east and east-south comes from Puwei and Pucheng-Qianliyuan sag.By means of comprehensively analyzing the characteristics of sand bodies, faults and the disposition relationship between them, three kinds of migration system of sand body, fault and fault-sand are found and their distribution law is described. According to oil-source correlation and the spatial relationship between oil and source rock, in the distribution area of the same oil, the oil migration paths are analyzed by the indexes of biomarker and nitrogen compounds. The oil and gas migrated from Puwei sag to the west and north-west area along sand type and fault-sand type migration systems, charged to the east zone along fault-sand type migration system. The active periods of main faults are match with the hydrocarbon migration times and the oil and gas migrated to the upper Es2 and Es1 strata along fault type migration system.The stages of hydrocarbon accumulation and the reservoir forming dynamic are clearly. The hydrocarbon generation, expulsion, and migration histories of Puwei sag are studied using simulation technology. Based on the flow-path characteristics, the Puwei sag areas are divided into five accumulation systems. To every system, the main time of hydrocarbon migration is terminal of paleogene. During this time, the amount of hydrocarbon generated and expulsed from source rocks is large. The hydrocarbon migrated from sag area to the pressure transitional zone of slopes along the sand driven by abnormal high pressure of central sag. Some oil and gas accumulated formed lithologic or structural-lithologic reservoirs. Some continuing migrated to the low pressure zone of horst belts and faulted anticline areas formed structural reservoirs. Also the oil and gas of Es3 migrated to Es2 to Es1 along source faults and secondary faults driven by tectonic stress and formation pressure and the hydrocarbon charging terminated basically. From Quaternary period to now, there is hydrocarbon generated for the second time in source rocks, but the amount of hydrocarbon generated and expulsed is little, mainly charging to source rock layer in sag area.
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