ABSTRACT
Effective management of microbiologically influenced corrosion (MIC) in upstream oil and gas assets begins in the design stage and continues through construction, commissioning, and operations until the point of abandonment and decommissioning.
Corrosion management (CM) is a structured process that is applied concurrently to abiotic and biotic internal corrosion threats throughout all stages of asset life. The essence of the corrosion management process consists of the assessment of corrosion threats, the identification of mitigation and preventive measures to reduce the severity and likelihood of those threats, and monitoring the performance and the effectiveness of the control measures.
In addition to MIC, oil and gas assets are often exposed to abiotic internal corrosion threats, resulting from CO2, H2S, oxygen, and other corrosive species as well as flow-assisted corrosion, erosion, under-deposit corrosion, and cracking. These corrosion threats may occur concurrently or in synergy with one 142another, and they may change over time in the different stages of asset life. To respond to changes in the types or severity of corrosion threats, the corrosion management process must be a continuing cycle of assessment, mitigation, and monitoring, and it must also incorporate learning from failures.
While microorganisms exist in essentially all upstream production assets, determining their role in internal corrosion and developing effective corrosion management strategies requires a consistent and methodical approach. In the oil and gas industry, MIC assessment efforts have historically focused on enumeration of planktonic rather than sessile microorganisms in biofilms, thereby discounting surface phenomena that directly influence both localized abiotic corrosion and MIC. Preventive and mitigative measures that are based on an understanding of biofilms, surface microbiological consortia and activity, and their relationship to corrosion are significantly more effective in managing MIC than measures based only on planktonic culture data (Larsen et al. 2008; Eckert 2015).
A number of recent case histories illustrate the benefits of improved MIC diagnostics based on integrating data from molecular microbiological methods (MMM) with corrosion monitoring and operational information. Although the industry is witnessing growing use of MMM for managing MIC, a procedure for clearly linking microbiological conditions with electrochemical corrosion initiation and propagation mechanisms is still emerging.
This chapter discusses a holistic approach to MIC management that incorporates the latest diagnostic methods and data integration within the corrosion management process, improving the operator’s ability to manage MIC threats.
