Abstract: High resolution Scanning Electron Microscope ( SEM) can directly observe the surface mor-phology and mineral composition of the samples, and Energy Dispersive Spectrometer ( EDS) can conductquantitative or semi-quantitative composition analysis. The combination of SEM and EDS plays an important role in mineral composition identification. In this paper, the mineral composition of paleogene shalereservoir in Liaozhong Sag was studied by argon ion polishing technology , field emission scanning electronmicroscope and energy spectrum analysis. The results show that the Backscattered Electrons ( BE) arenot as good as the secondary electrons in reflecting the surface morphology details of the sample whenstudying the mineral in shale reservoir by sem, but the BE can show the difference of chemical composition or atomic number in the microregion, and the mineral can be preliminarily identified by gray scaledifference and mineral morphology characteristics. Therefore , for minerals with similar morphology and little difference in the gray scale of backscattered electron images, they can be distinguished according to theelement composition and atomic ratio analyzed by energy spectrum. For unusual minerals, the composition and distribution of elements can be inferred from energy spectrum.

Key words: Scanning Electron Microscope ( SEM), Energy Dispersive Spectrometer ( EDS), mineral i-dentification: shale reservoir, Backscattered Electron ( BE)