Study on the Effect of Carbon Dioxide on the Direct Corrosion Process of Pipeline Steel Induced by Sulfate Reducing Bacteria

摘要

There are numerous oil reservoirs exhibiting low permeability. The strategic injection of carbon dioxide (CO 2) into these reservoirs has been identified as a promising approach to enhance the extraction efficiency of low-permeability oil fields [1]. However, those operations are often compromised by the corrosion failure of pipeline steel, which can have adverse effect on the overall exploitation process. The CO 2 can be used as a carbon source for microorganisms i n underground pipelines for chemoautotrophic metabolism and induce microbiological induced corrosion (MIC). As a typical corrosion microorganism, sulfate reducing bacteria (SRB) is capable of directly causing E -MIC and accelerate iron corrosion via chemical attack of its corrosive metabolites [2]. Some studies showed that the E -MIC may cause more severe corrosion than M -MIC. This work focus on whether the injection of CO 2 will have an impact on this corrosion process of MIC. In this present study, the corrosion behavior of X70 pipeline steel induced by Desulfovibrio Bizertensis SY-1 was studied via electrochemical measurements and weightloss experiments. The bacterial culture experiment found that CO2 had little effect on the cell number and attachment ability of SRB bacteria. The weightloss experiments results showed that corrosion of pipeline steel is more severe in the CO2 system and the proportion of E-MIC in corrosion in CO2 systems is significantly increased. Surface investigations revealed that corrosion products in CO2 systems are denser and pitting pits are generally deeper. Cytochrome c level tests shows that the Cyt C level in SRB increased by about 20% in CO2 system. The result of electrochemical measurements is consistent with the above conclusion, which suggests that CO2 promotes the secretion of Cyt C in SRB cells, thereby promoting their direct corrosion.