Natural Radionuclides Behavior of 238U, 232Th and 40K in the Prometeo-1 Well: A Case Study from the Middle Magdalena Valley Basin, Colombia

Abstract The development of research about preservation of the human health and environment have taken a relevant place in several industries around the world. In Colombia, recently, has been developing some studies respect to the behavior of natural radionuclides in the hydrocarbon areas in zones of interest at the Middle Magdalena Valley Basin (MMVB), these results have been considerably variables and dependents of the multi elemental composition, type of rocks, rock-fluid interactions, among others. The Prometeo-1 Well, has showed values of radioactivity concentrations from the chains 238U, 232Th, and 40K between 58 – 82, 14 – 67, and 185 – 287 Bq/kg, respectively, from formation rocks at depth between 8180 and 9260 ft; these results are related with concentrations of chemical elements such as calcium, silicium, and aluminum, and minerals such as calcite, quartz, and pyrite. The relationship between radioactivity concentrations and multi elemental composition is so important in the results for this well in the Absorbed Doses Rate (92 nGy/h) and the Annual Effective Dose Equivalent (112 µSv/y); these values are very close to the world average and suggest a specific review to know the true radiological risk. In this way, this work shows an evaluation of the natural radionuclide behavior in rocks from the Prometeo-1 Well through measurement of radioactivity concentration using gamma spectrometry in the formation members Lower Lidita and Salada, subsequently, with the results obtained using XRF and DRX a concentration relationship was made allowing to know the radioactive content, besides, the results in both formation members were compared, measuring the radiological risk using defined math equations. Finally, the results allowed to obtain a general view of point about natural radionuclides behavior in the well and create a technical criterion related to a possible radiological risk, waiting the definition of the radioactive baseline at the MMVB.