The oil and gas industry deals with large amounts of water. In 2009, in the US alone, over 18.9 billion barrels of water were managed in the industry. With hydraulic fracturing (frac) on the rise, water volumes used in the oil and gas industry are increasing, and so is the reuse of produced water in these fracs.
All of this water contains microorganisms. While the types of organisms vary widely, the most detrimental to the oil and gas industry are the sulfatereducing bacteria (SRBs). These SRBs are present in all waters handled in the oilfield, and they sour reservoirs by converting sulfate ions to hydrogen sulfide (H2S). The potential for SRB activity is even greater when operations rely on injecting produced water. For this reason, biocides play a major role in frac fluid treatment and any water injected downhole.
The most common are non-oxidizing organic biocides, referred to as ‘conventional’ biocides. These include glutaraldehydes (glut), quaternary amines (quat) and others. Many SRBs become resistant to conventional biocides, limiting effectiveness and requiring operators to increase the concentrations used. Many conventional non-oxidizing biocides are also carcinogenic, so using more chemicals can present potential health risks for workers.