Abstract
Corrosive biofilm formation on metal surfaces can have serious impacts on the infrastructure of the natural gas and oil industries. Once initiated, biofilms are extremely difficult to remove even with current mechanical cleaning methods (i.e., pigging) as large sections of a pipeline system are inaccessible. It is also well known that the application of biocides alone does not completely remove the protective slime layer of biofilms. In this study, we hypothesized that the addition of appropriate enzymes or cocktails of enzymes may be able to significantly enhance the effectiveness of biocides and may represent a potential future solution to biofilm prevention and mitigation. The application of enzymes, which are environmentally benign and biodegradable, in the natural gas and oil industry may provide a needed treatment alternative by either eliminating or reducing the widespread use of biocides. Through this proof of concept research project we successfully established and maintained MIC biofilms for subsequent testing with various enzyme preparations. After two months of incubation in a bioreactor inoculated with a consortium of MIC microorganisms, the presence of corrosive MIC biofilms were confirmed on steel coupons. The addition of individual commercial enzyme preparations and mixtures of enzymes were able to reduce the biofilm load. Consistent with this result was the apparent reduction in the numbers of microorganisms associated with the treated biofilms. Together the data suggests that the application of enzymes may prove to be beneficial in the degradation of the MIC biofilm structure.
Introduction
The deterioration of metal due to the action of microbial activity is known as bio-corrosion or Microbiologically Influenced Corrosion (MIC). Corrosion due to the presence and activities of microorganisms can degrade the integrity, safety, and reliability of natural gas and oil pipeline operations. This condition can lead to significant degradation of the pipe surface and, if left unchecked, can ultimately cause a catastrophic pipe failure. While corrosion management has improved over the past several decades, MIC still remains a high-priority issue for the petroleum industry, especially in areas with “wet” gas and where aging pipeline infrastructure exists. The problem has intensified in recent years with the growing incidence of reservoir souring caused by the use of water-based hydraulic fracturing gas well treatments.1
