Types and Favorable Oil Accumulation Parts of Fault Dense Belts in Fuyang Formation of Sanzhao Depression,Songliao Basin

The controlling effect of fault dense belts on the preferred direction of oil-gas migration is discussed and favorable parts of fault dense belts for oil accumulation inside and outside oil source area are discussed based on the characteristics of fault dense belts of Fuyang Formation in Sanzhao Depression,combining with the oil and gas distribution of in Fuyang Formation of study area in this paper.The results show that there are four types of fault dense belts in Fuyang Formation of Sanzhao Depres- sion,namely antithetic-graben-antithetic fault terrace,horst-graben-antithetic fault terrace,antithetic-graben-consequent fault terrace,and horst-graben-consequent fault terrace.The strike of fault dense belt is the preferred direction of oil-gas migration and horsts and antithetic inside oil source area of fault dense belts are favorable parts for oil accumulation where the strikes of fault dense belt and the layer are parallel or small-angle intersection.Inside oil source area horst and antithetic of fault dense belts are favorable parts for oil accumulation.And horsts and antithetic outside oil source area are favorable parts for oil accu- mulation and the grabens are secondary favorable ones where the angle of the strikes of fault dense belt and layer ranges from 0 to 45degrees.The antithetic and horsts are preferential for oil accumulation where the angle ranges from 45to 90degrees.