Study On Corrosion Behavior Of Sulfate Reducing Bacteria In X52 Oil Pipeline

Microbiologically influnenced corrosion caused huge economic losses to national economy. Sulfate reducing bacterial (SRB) is one of the most important bacteria. Based on the research progress of microbial corrosion of oil pipeline at home and abroad, taking the X52 oil pipeline in Xinjiang as the research object. The local severe pit corrosion, oil water obvious stratification, small flow rate, the presence of water and other corrosion status of the present, it is suggested that the presence of SRB and propagation lead to severe local corrosion.Component analysis was used to analyze the components of crude oil and the corrosion scale in the pipe.SRB from crude oil pipeline were enrichment culture and measured the change trend of H2S from the solution with SRB in the growth cycle to prove that the existence of SRB may be the cause of increasing sulfur content in the oil pipeline and accelerating corrosion. Corrosion coupon test and electrochemical experiment were used to research the corrosion behavior of carbon steel in SRB and sterile mediums and investigated the corrosion morphology and products of the steel by means of scanning slectron microscopy(SEM) and x-ray diffraction(XRD). The strain TL-1, a sulfate reducing bacteria, was isolated from the petroleum pipeline and the influencing factors of the corrosion of the strains were studied.The results showed that:crude oil of the oil pipeline contains low sulfur content while sulfur content in corrosion scale is relatively high.There exist SRB in the oil pipeline, and corrosion of carbon steel is more serious in water containing bacteria. Hydrogen sulfide gas produced in the process of metabolism may be one of the reasons for the increase of sulfur, and increased the possibility of stress cracking of pipeline steel. The corrosion rate of carbon steel in solution with SRB was 0.077 mm/a, which was much higher than that in the sterile solution with 0.036 mm/a.The variation of the radius of the impedance spectra was closely related to the biofilm on the surface of the sample, and the impedance spectral radius is decreased in solution with SRB. SRB caused serious local corrosion of carbon steel, and the content of S in the corrosion product of the solution with SRB was 8.58%, while that of the sterile solution was 0.48%. The metabolites of SRB are mainly sulfur compounds (such as ferrous sulfide), which is one of the main causes of local corrosion of the carbon steel. Carbon source, temperature, pH value and salinity influence the corrosion rate of carbon steel. The strain of SRB growth rate had obvious difference with different carbon source, the most suitable temperature for the growth of SRB was about 35?, the optimal pH of SRB was about 7.5, the optimum concentration of NaCl was 0.5%, the strain belong to bacillus, Clostridium.Corrosion protection can be divided into physical method, chemical methord and biological methords.