Abstract：Based on Zeoppritz equation's approximation formula of porous liquid-saturated viscoelastic media which was proposed by Russell,new normarised elastic impedance formula which were expressed by fluid factor,Lame Constants and density were derived based on elastic impedance principle,and the fluid factor,Lame Constants could be directly extracted from elastic impedance data volume through inversion,as a result the elastic impedance and fluid factor can be linked by taking advantages of high anti-noise of conventional elastic impedance and visibility of the fluid identification by using fluid factor,moreover the direct extraction method for fluid factor decreases the error accumulation in indirect calculation,providing a new way for reservoir fluid prediction.By using fluid factor which was extracted from Y3 area in SL Oil-field with the method introduced in this paper,the different fluid types can be effectively classified,the sensitivity of the fluid factor to fluid type is better than other conventional attributes,its identification to 2nd member of Shahejie Formation is more accurate,and the good application effects were achieved for reservoir fluid identification and residual oil searching.
