Summary The development of exploration in unconventional resources in Colombia has been an important advance in the hydrocarbons industry in this country, however, there are a lot of aspects to evaluate for an exploitation efficient and safe, one of this is the natural radioactivity, represented by the Naturally Occurring Radioactive Materials (NORM) presents in crust rocks since earth formation. Typically, all rocks contain both U-238 and Th-232 decay series, generating other radioisotopes associated according to the decay mode (alpha or beta). This project allows to demonstrate a better understanding of the activity concentration of the main natural radionuclides presents (U-238 and Th-232 decays), entrenching the previous studies and give an important value to build the first radiological modeling in this basin. Also, this research showed low doses and low activity concentrations of NORM, however, the results of multi elemental composition showed a high variability in the geological conditions and geochemical interaction which are very interesting and require a continuous monitoring at the basin. Finally, all results can be used as a tool to improve the way to radiological monitoring in oil & gas industry in Colombia and an apport to the evaluation of the care to health and environmental.