Demystifying MIC Mechanisms

Microbiologically Induced Corrosion (MIC) is becoming more and more important, especially to the oil and gas industry as more and more reservoirs are soured due to increased practice of water flooding and pipelines are aging (some even beyond their anticipated life expectancies). Despite the fact that MIC research has been going on for several decades, there is much confusion in the MIC literature regarding the fundamental mechanisms in MIC. This has greatly hindered the development of reliable prediction and new mitigation methods. A new MIC theory entitled Biocatalytic Cathodic Sulfate Reduction (BCSR) theory was presented in NACE/2009. It sheds some lights on MIC mechanisms. This work demonstrates how the theory together with bioenergetics, electrochemical kinetics, and mass transfer can be used to explain various mysteries in MIC. Some experimental data and model simulation results for MIC due to sulfate reducing bacteria (SRB) and acid producing bacteria (APB) are used in the explanations.