Abstract: This paper systematically studies the control of faults on hydrocarbon migration and accumulation in Nanpu sag and predicts favorable exploration targets through establishing fault transporting models.Research shows that positive local structures such as horst/half horst,negative flower structure combinations of anticline,fault terrace belt of anticline and so on are the favorable for hydrocarbon accumulation.When the juxtaposition thickness of faults in Ed² cap rock is less than 90-95 m,hydrocarbons can penetrate the cap rock and accumulate in the middle-shallow layer.The greater the fault density is,the shallower the hydrocarbon accumulation is.Type Ⅴ and Ⅵ faults are source rock-rooted faults and two or more intersected faults are the preponderant pathways of vertical hydrocarbon migration,and some hydrocarbons may migrate along reservoirs with a net-to-gross ratio of over 20%.The hydrocarbons charging into the fault traps can accumulate and be preserved in large scale only when both the palaeo and current sealing ability of faults are strong enough.Favorable deep exploration targets include the local positive structures related with type Ⅰ,Ⅱ and Ⅳ faults and reservoirs with high net-to-gross ratio as well as local positive structures related with type Ⅴ and Ⅵ faults and reservoirs having a juxtaposition thickness of Ed₂ cap rock over 90-95 m and high net-to-gross ratio.While the shallow-to-moderate favorable exploration targets include positive local structures related with type Ⅴ and Ⅵ faults and reservoirs having a juxtaposition thickness of Ed² cap rock less than 90-95 m and high net-to-gross ratio as well as that with good lateral fault sealing ability.

Key words: net-to-gross ratio, juxtaposition thickness, fault combination, positive local structure, lateral fault sealing ability, hydrocarbon enrichment, Nanpu Sag