乌什凹陷是塔里木盆地一个新的勘探领域，主要目的层段为下白垩统;由于地表及地下地层的复杂性，其地震资料信噪比低，地震层位预测与实钻差别大。尝试性地利用自然伽玛能谱测井资料对该区的层序、地层进行了识别、划分，进而对有关目的层段进行了预测。指出自然伽玛能谱测井在测量地层自然伽玛的同时，还可测量铀（U）、钍（Th）、钾（K）的含量;由于地层的自然伽玛能谱特征反映了沉积岩的放射性特征，对这种特征进行详细分析,可以了解当时的沉积环境;通过对自然伽玛能谱数据的处理可得到Th/U、U/GR值曲线,而据Th/U值并结合区域资料可以确定风化界面，U/GR值则可反映水体环境的变化，可以确定特定范围内的体系域;以上述资料为基础，用等时、旋回观点进行层位预测和地层对比,在乌什地区油气勘探中获得了良好效果.

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.