Abstract: The analysis of oil sources shows that the crude oil of the lower members of Guantao Formation in southwest Gudao Oilfield are mainly from the source rock of Sha-3 member in Gunan sag.The pool types of oil reservior are mainly structure reservior.The main controlling factor of the formation of southwest Gudao Oilfield reservoir is the fault sealing ability.The study on fault sealing ability indicates that the fault sealing of Lower-member 7-8 Guantao Formation is good and is favorable for the formation of reservoirs.While the fault sealing of Lower-member 9-11 Guantao Formation is bad and can be used as the transportation passage of oil and gas.The oil-forming model of the studied area can be summed as Bonan fault terrace transportation and,fault-sealing pool-forming models.Fault block reservoirs and antithetic dragged anticline structure reservoir will be the next important exploration direction.The development effect of this model is very good， and the good development prospect of Guantao Formation in southwest Gudao Oilfield is demonstrated.

Key words: Gudao Oilfield, Guantao Formation, oil-source correlation, fault sealing ability, accumulation model