In recent years

the development of shale oil and gas shows that shale heterogeneity and lateral orientation have relatively great impacts on single well shale gas production

recovery factor and the economy of shale gas exploitation

and natural micro-fracture is the main factor resulting in shale heterogeneity.Accordingly

to carry out research on the natural micro-fractures and prediction of sweet spots within shale has become an inevitable choice for successful emplacement of high-yielding wells and improving economic benefits of shale gas exploitation.Based on the high resolution 3C/3D seismic data in Marcellus shale play within Appalachian Basin

North America

natural micro-fracture zone of Marcellus shale was predicted by means of fast and slow converted shear wave(PSV-1/PSV-2)integrated interpretation

then the open/closed fractures and gas-bearing property of extensional micro-fractures were separately identified and detected by utilizing combined attribute parameters like joint inversion density

velocity ratio of compressional and converted wave(v

P

/v

S

)extracted from joint inversion of compressional wave and converted shear wave(PP-PS).In addition

drilling data were used to verify the sweet spots predicted by geophysical method in Marcellus shale.Joint inversion technique(PP-PS) has outstanding advantages in natural extensional micro-fractures identification and gas-bearing detection

which can effectively reduce the drilling risk.