Evaluating the Radiological Hazards of Contaminated Soil with Naturally Occurring Radioactive Materials (NORM) Resulting from Produced Water during Oil & Gas Production

Uncontrolled disposal of water extracted during oil and gas production leads to contamination of the surrounding soil with naturally occurring radioactive materials (NORM), resulting in contamination of huge volumes of soil with radium isotopes (Ra-226 and Ra-228). In order to assess the radiological health hazards and excess lifetime cancer risks associated with the contaminated soil, the concentration of the naturally occurring radionuclides Ra-226, Th-232 and K-40 were determined using gamma ray spectrometry. The mean activity concentrations of Ra-226, Th-232 and K-40 were found to be 1939.56, 737.86 and198.21Bq kg(-1), respectively. The results of the radiological indices and annual effective dose & cancer risk estimated by RESRAD obtained in this study were all higher than their worldwide mean values. This indicates the danger of discharging the produced water resulting from oil and gas production into evaporation ponds without taking preventive measures that limit soil contamination and thus limiting workers' exposure to natural radioactive materials. There is a need to establish clear national rules and regulations for dealing with natural radioactive materials resulting from various oil and gas fields in order to contribute to the control and management policy of technologically enhanced naturally occurring radioactive materials (TE-NORM) released from this industry.