Role of Fe oxide in the underdeposit corrosion of pipeline steel in oilfield produced water containing SRB

The corrosion behavior of C20 pipeline steel was studied under Fe oxide and sand deposits in oilfield produced water containing sulfate-reducing bacteria (SRB) via electrochemical techniques and surface analyses. A galvanic current of about 2 & mu;Acm(-2) was detected when the Fe oxide deposited sample and the bare steel were coupled in zero resistance ammeter (ZRA) mode, with the former being the anodic member of the couple. The Fe oxide deposited steel recorded severe localized corrosion after 14 days of testing in the SRB inoculated oilfield produced water. Corrosion severity decreased on the sand-deposited steel, with general corrosion as the dominant morphology of surface attack. The development of product film was a vital factor in steel corrosion under the Fe oxide deposit.