Lecture 2
时间:2011-05-24 点击:

Lecture:A Coupled Electrochemical-Geochemical Model of Corrosion for Mild Steel in High-Pressure CO2-Saline Environments

Lecturer:PH.D  Jiabin Han

time: April 25   4:30 pm

place:Founder Building 301

host:Ruqiang Zou

Abstract of the lecture:
       We have developed a mechanistic model for predicting corrosion rates of mild steel used in most wellbore systems. The model includes an aqueous geochemistry and an electrochemistry module. The water chemistry module uses the Pitzer formulation for activity and Duan et al.’s 2006 model for CO2 solubility. The electrochemical module accounts for both mass transfer processes and electrochemical kinetics. The electrochemistry includes the primary oxidation reaction (the dissolution of iron) and the primary reduction reactions (the formation of H2 gas from carbonic acid, hydrogen ion, and/or water).
       At high CO2 pressures, the dominant corrosion reaction is Fe + 2H2CO3 = Fe2+ + 2HCO3- + H2(g) and is driven by CO2 solubility rather than solution acidity. For similar reasons, high salinity solutions reduce corrosion rates significantly mainly due to the “salting-out” effect of reduced CO2 solubility. For example, an increase in salinity from 5 to 20 wt% salt results in a 50% reduction in corrosion rate as confirmed in our experiments.
 

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