Investigation of microbial corrosion behavior of petroleum tubing steel

Petroleum is a rich source of energy for both fuel and the maintenance of microorganisms. When the physicochemical conditions of the oil and the metabolic activities of the microorganisms come together, serious corrosion problems can occur in the metal parts used in oil productionleading to economic loses. Microorganisms present in petroleum reservoirs can cause microbiologically induced corrosion (MIC) by inducing localized changes in the aqueous medium. MIC is known to cause serious economic losses due to damage inoil pipelines and storage tanks. It has been reported that approximately 20% of corrosion problems in the oil and gas industry are caused by microorganisms. In this study, the effect of oil water phase taken from oil field in Adiyaman on microbial corrosion behavior of N80 steel using petroleum system was carried out for 4 months by both gravimetric and electrochemical methods.Two different laboratory scale devices, one as a test and one as acontrol for microbiological corrosion, were installed in duplicate under the same conditions. Potentiodynamic polarization method wasused in electrochemical experiments. Measurements were performed at the times indicated above. Corrosion rate was calculated from the Icorrvalues. Experiment and control have been established. Metal surface was examined by Scanning Electron Microscopy (SEM). The weight loss of the test and control coupons was found to increase with time (p <0.01 and p <0.01, respectively), and the highest weight loss values were found to be 0.3343 g / cm2 and 1.7928 g / cm2 at 2880 h, respectively. The highest corrosion rates in the test and control coupons were determined as 25.55 mpy and 54.39 mpy at 24 and 2880 h, respectively, while the lowest corrosion rates were found to be 8.09 mpy and 9.30 mpy at 2160 and 72 h,respectively.It was found that the corrosion rate of thetest coupons was higher than the corrosion rate of the control up to 720 h, but decreased after that. This indicates that microorganisms can be held responsible for corrosion occurring in metal up to 720 h. As a matter of fact, the SEM image taken from the surface of the coupon at 1080 h also supports these findings. As a result of the SEM analysis, it was found that during the experiment, corrosion products were formed on the surface of the test coupons in sandy structure and in superimposed layers. It was determined that the corrosion potential of the test coupons was higher than the control values until 168th hour and more active values in the following hours. The most active corrosion potential of the test coupons was found to be -0.888 V at 504. h. It was found that the corrosion potential values of the control device varied during the experiment, reaching the highest value at 2160 h (-0.640) and the most active value at 168 h (-0.830). The maximum corrosion rate of the test coupons was determined as 71.11 mpy at 504 h and the lowest corrosion rate was 2.17 mpy at 8 h. The highest level of corrosion rate reached by control coupons was found to be 54.66 mpy at 2880 h, and the lowest rate of chorion at 0.08 mpy at 720 h. It was found that the corrosion rate of the test coupons was significantly higher than the control (p <0.05), but decreased after 1080 hours. This indicatesthat microbiologically induced corrosionoccured. As a result, the data obtained from both electrochemical and gravimetric experiments indicate that the N80 steel exposed to the produced water is subjected to microbiological corrosion.