Validation of a pilot-scale non-thermal plasma reactor for the treatment of flowback water from unconventional oil and gas operations

Abstract

Argentina possesses one of the world's largest reserves of unconventional oil and gas. Their exploitation through hydraulic fracturing generates large volumes of flowback water, a liquid effluent containing microorganisms and chemical additives used during the extraction process. Microorganisms present in these waters are the primary cause of microbiologically influenced corrosion (MIC) in production facilities. Currently, their control relies primarily on the application of biocides, which entails high operating costs. Among the chemical additives present in flowback water is partially hydrolyzed polyacrylamide (HPAM), whose removal represents an additional challenge for the treatment of these effluents. In this work, a pilot-scale (TRL 6) falling thin-film non-thermal plasma reactor was validated for the inactivation of microorganisms in flowback water and the degradation of HPAM. The experiments were carried out in batch recirculation mode using air and oxygen as feed gases. A two- to three-order-of-magnitude reduction in microbial load was achieved, together with a significant decrease in MIC-associated bacteria. In addition, HPAM degradation efficiencies exceeding 90% were obtained, accompanied by a marked reduction in the viscosity of the treated solutions. Overall, these results support the use of the plasma for the inactivation of microorganisms and the degradation of HPAM in flowback water from unconventional oil and gas production, paving the way for future efforts aimed at scaling up the technology.