The Deputy Vice Chancellor of the Federal University of Petroleum and Resources, FUPRE, Engr. (Prof) Akpofure Rim-Rukeh, has charged the Nigeria National Petroleum Corporation, NNPC and other oil and gas firms to be mindful of the impact of microbial corrosion on petroleum production facilities.
Rim-Rukeh had also prevailed on the oil and gas firms to periodically ensure the integrity of their facilities, calling on them to support research initiatives of the Universities at all times.
Engr. (Prof) Rim-Rukeh gave this charge while delivering the university’s inaugural lecture with the theme: “Microbial Corrosion: Latent Enemy of Oil and Gas Production Facilities”, making it the third in the series of inaugural lectures of the Federal University of Petroleum Resources, Effurun Delta State.
He said during the lecture that every refined metal is at a high energy state and hence has; every tendency to return to its original ore of low energy state through a process called corrosion, pointing out that the extent to which corrosion proceeds is determined by number of factors which could be biotic (living) or abiotic (non-living).
Rim-Rukeh explained that Corrosion process where microorganisms (living factor) are able to initiate, facilitate or accelerate the corrosion reaction without changing its electrochemical nature is called microbial corrosion and also known as biocorrosion or microbiologically influenced corrosion.
He said, “It has been estimated that 40% of all internal pipeline corrosion in the gas industry is attributed to microbial corrosion. Annual cost of all forms of corrosion to the oil and gas industries in the United States is $13.4 billion, of which microbial corrosion accounted for about $2 billion.
Meanwhile, Prof. Rim-Rukeh had also revealed that Niger-Delta environment is prone to microbial corrosion and that it is real in the oil and gas producing area of Niger Delta, pointing out that this was inline with his research findings that had span the period of twelve years.
Prof. Rum-Rukeh said, “The first step in investigating metal failure as a result of microbiologically influenced corrosion is to study the physico-chemical and biological characteristics of the environment of the metal failure.
“Physico-chemical and biological characteristics of surface water, soils and produced water samples, collected from parts of the Niger Delta and analysed indicate that parts of the Niger Delta environment especially within areas of industrial activities correspond to an environment that promotes microbial corrosion.
“The contribution of Iron-oxidizing Bacteria (Leptothrix discophora to the corrosion of low carbon steel, (commonly used material for oil and gas facilities), saying that Leptothrix discophora is an iron bacterium that was isolated from New Calabar River.
“The presence of Leptothrix discophora increased the corrosion rate by about 123 percent and a pipeline of wall thickness 0.25 inch will corrode microbiologically after 12 years of installation at a rate of 2.08mpy.”
Prof. Rim-Rukeh also revealed that the relevance of Biofilm in Microbial corrosion, saying in every environment there are microorganisms which are usually found as free floating (planktonic) or attached on any surface (sessile), pointing out that nearly every species of microorganisms can adhere to surfaces and to each other to form what is called biofilm.
According to Prof. Rim-Rukeh, biofilm is an aggregate of microorganisms in which cells adhere to each other on the surface of a solid material, and that microbial corrosion is a problem of biofilm, pointing out that reliable and representative information about biofilms are mandatory for a better understanding of microbial corrosion.
He said, “Biofilms grow on surfaces in aquatic systems wherever nutrients are available for bacteria utilization such as, teeth (dental plague) catheters, stones in riverbeds, trickling filters, ship hulls, water, sewage pipelines and cooling/heating water systems, on the surface of and inside plants, pipelines of the offshore oil and gas industry, and bioreactors.
“The introduction of gradients and patchiness is one of the main ways in which biofilm influence corrosion. One direct effect of non-uniform or patchy colonization by bacteria is the formation of differential aeration cells, where areas under respiring colonies are depleted of oxygen relative to surrounding non-colonized areas. Thus, colony formation gives rise to potential differences and therefore to corrosion currents.
“Under aerobic conditions, the areas under the colonies become anodic, leading to metal dissolution indicating that biofilm represents mainly an oxygen-consuming ecosystem.