ABSTRACT
Microbiologically influenced corrosion (MIC) is a common problem in the oil and gas industry. MIC is an immense threat especially inside of pipelines, especially by Sulfate Reducing Bacteria (SRB). For this purpose, MIC by SRB was investigated in experiments using split-cell zero resistance ammetry (SC-ZRA) measurements. To understand the extent and activity of MIC by SRB, various experiments were conducted where carbon steel coupon was deployed in laboratory synthesized media, which was formulated from the oil and gas pipeline sludge using elemental analysis. SC-ZRA incubations were inoculated with SRB enrichment isolated from contaminated pipeline sludge. One side of the SC-ZRA is inoculated with SRB enrichment (WE1) and the other side of the SC-ZRA is kept sterile (WE2). Current and potential between the two coupons was measured. Series of batch experiments are also conducted with the same enrichment and synthetic media. When SC-ZRA was conducted for 30-days, biofilm attachment was not observed under scanning electron microscopy (SEM) as the biofilm was heavily encrusted by corrosion products. When the experiment was conducted for 17-days, some microbial attachment was observed but the organisms were covered with iron sulfide (corrosion product), which was formed as a byproduct due to microbial metabolism. Consequently, intense corrosion and pitting was observed on the coupon exposed to the SRBs in the 30-days run. Weight loss for WE2 was higher than WE1 at the end of the experiment. For the 17-days run, no pitting was observed for the inoculated coupons, and the WE1 side had a higher mass loss when compared to the WE2 side. SC-ZRA technique can be used to characterize microbial activity, in this work with SRB. This technique can also be used as a quick monitoring tool for detecting the extent of microbial corrosion for the oil and gas systems.
