Effect of ionizing radiation on microorganisms present in produced water from conventional and unconventional oil production in Argentina

Abstract

Microbiologically influenced corrosion (MIC) is a type of localized corrosion caused by the metabolic activity of microorganisms and is responsible for at least 10–20% of incidents in the oil and gas industry. Therefore, researchers are focused on technologies to prevent MIC. In this study, gamma radiation using a Cobalt-60 (60Co) source was applied to the microbial community present in oil-field produced water samples obtained from conventional (COP) and unconventional (UOP) oil processes. Doses of 5, 10, 15, and 20 kGy were used. The total bacterial concentration and the efficiency of the treatment were determined as a function of the dose and the time after irradiation through ATP quantification. The content of specific genes was quantified through qPCR. Inaddition, microbial diversity was monitored through metagenomic study of the bacterial 16S gene. Total bacteria, sulfate-reducing bacteria (SRB), and Arcobacter sp. were quantified in COP water samples. Meanwhile, total bacteria, SRB, thiosulfate-reducing bacteria, and Halanaerobium sp. were quantified in UOP water samples. The irradiation process was highly efficiency for the microbiological control in COP and UOP water samples. A decrease in the microbial load of at least one logarithm was obtained for all the samples. A greater decrease in cell concentration was observed after 15 and 30 days of irradiation, with a greater decay (>90%) at higher doses administered. Molecular analysis revealed that bacteria such as Halanaerobium sp., Marinobacterium sp., Pseudomonas sp., and Arcobater sp. showed a decreasing trend with increasing irradiation doses rates. The findings of this investigation suggest that the application of ionizing radiation may enhance the efficacy of microbial treatment in produced waters in the oil and gas industry.