Impact and Control of Microbial Biofilms in the Oil and Gas Industry

Abstract

Microbial biofilm formation is the result of an accumulation process that starts immediately after immersion of metal in an aqueous environment. The growth of biofilm is considered to be a result of complex processes involving transport of organic and inorganic molecules and microbial cells to the surface, adsorption of molecules to the surface, and initial attachment of microbial cells, followed by their irreversible adhesion facilitated by production of extracellular polymeric substances (EPS). Once attached, the organisms begin to produce a material called extracellular biopolymer, or ‘slime’, which provides a more suitable protective environment for the survival of the organism. The EPS in biofilm consists of lipids, polysaccharides, proteins, and nucleic acids. The content of these macromolecules in EPS varies, depending on bacterial species and growth conditions. One of the important properties of EPS is their ability to form a complex with metal ions. This initial film is able to alter the electrostatic charges and wettability of the metal surface, facilitating its further colonization by bacteria. The presence of biofilm in oil and gas facilities accelerates corrosion rates of carbon steel and metals, and increases maintenance and operational problems, which may lead to reduction in flow, heat transfer rates, fouling, corrosion, and scale. Biofilm and biofilm producers have been successfully used to remediate and clean up an oily seawater, which provides an indication that they can be employed in the oil and gas industry for bioremediation of soil.