Application of natural gamma ray logging and natural gamma spectrometry logging to recovering paleoenvironment of sedimentary basin

The application of the natural gamma ray (GR) curve and the natural gamma spectrometry (NGS) curve to the Member 3 of the Shahejie Formation from the well Niu-38 in the Dongying depression indicates that the GR curve can not reflect the change of the paleoenvironment well, but the curves of uranium (U) and the ratio of thorium to uranium (Th/U) from NGS are consistent with the change of paleoenvironment and have good correlation with the contents of carbon organic, which suggests that U and Th/U are better parameters for paleoenvironment than GR. In the quiet and deoxidize condition U and Th/U are much applicable, with the conditions having more oxidation their capability of application is weaken. So the application of the GR curve in the recovering of paleoenvironment should be together with the NGS curve, and the NGS curve should be used as a criterion.