The formatin of interest is the Lower Crataceous. Because of the complicate terrains and strata, the singal to noise ratio is very low. The interpreted layers have tremendous differences from what are drilled. This paper uses spectromery date to distingish the successions and predict the hydrocarbon potential. The spectrometry log does not only provide the total gamma ray of the formation, but also the contents of Uranium, Thorium and Kalium. The characteristics of the natural ray spectrometry log can reflect the radioactivity of sedimentary, and by the analysis of the correlated characteristics among them, we can recover the ancient depositional environment. By handling the digital information of the natural gamma ray spectrometry log, the curve of Th/U, U/GR can be gotten. The Th/U curve linked with the regional data indicates the weathered surface, and the U/GR curve indicates the changes of the environmental water. So the systems tracts in a certain area can be identified. On the basis of the systems tracts, the stratigraphical correlation and stratum prediction has got a good effect in the application of the Wushi area.