Biocides are utilized in hydraulic fracturing operations to prevent or remediate biofouling, souring, and Microbially Influenced Corrosion (MIC). Biofouling occurs when microorganisms form biofilms on shale or proppant surfaces, thus impeding the flow of hydrocarbons. Biofilms on piping and other equipment can lead to MIC and is linked to corrosion failures estimated to cost the industry billions of dollars. Lastly, microorganisms present in fracturing fluids often produce hydrogen sulfide thereby threatening the health and safety of workers and reducing the value of hydrocarbons produced.

Glutaraldehyde (Glut) and quaternary ammonium compounds (QAC) are the two most common non-oxidative biocides used in hydraulic fracturing. In general, glut and QAC are added at the blender during completions to inactivate microorganisms present in water and other injected fluids. Glut and QAC are sometimes used by themselves but are most often added in combination due to the belief that a combination of the two works better than each active individually. This paper will address the strengths and limitations of both glut and QAC, their applications, and compatibility with other additives in hydraulic fracturing.


Oil and gas operations worldwide are impacted by the presence of microorganisms. A variety of microorganisms can be found in the oilfield, dependent on the type of operation, geology, location, water source and water treatment utilized. Biocides are used in all stages of oil and gas development to control microorganisms and their detrimental impacts on production such as corrosion, biofouling, and souring. A wide number of biocides are used to control microorganisms, ranging from oxidizing biocides that react quickly but leave no residual activity, to preservatives which act slowly, but provide antimicrobial activity for weeks or months at a time. The spectrum of biocides used in oil and gas are covered by several excellent reviews and will not be detailed in this paper.1,2,3

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