The Microbial Menace: Protecting Oil & Gas Infrastructure from MIC

by: Suresh Divi, PhD, PE, APMP

Volatile market prices and geopolitical instability constantly challenge the oil and gas industry. Yet, a silent, unseen destroyer, Microbiologically Influenced Corrosion (MIC), lurks beneath the surface. Driven by microscopic organisms, this insidious degradation poses a significant and costly threat, silently eating away at pipelines, storage tanks, and critical infrastructure across the globe, often revealing itself only when the damage is extensive.

What is MIC and Why is it So Prevalent in Oil & Gas?

MIC forms when microorganisms—like bacteria, archaea, fungi, and algae—colonize metal surfaces and create biofilms. Within these slimy, protective layers, these microbes alter the local environment, accelerating the electrochemical reactions that cause corrosion. What makes MIC different from “traditional” corrosion is its biological nature, which makes it incredibly difficult to both find and fix.

Key Features of our Jet Impingement Testing System

While Microbiologically Influenced Corrosion (MIC) manifests in various forms of physical damage (pitting, crevice corrosion, etc.), the “types” of MIC are primarily categorized by the dominant microbial groups and their specific metabolic mechanisms that drive the corrosion process. Here are the key types of MIC and how they work:

1. Sulfate-Reducing Bacteria (SRB) MIC: SRB are anaerobic bacteria, meaning they thrive in oxygen-depleted environments. They are considered one of the most common and aggressive MIC culprits, especially in oil and gas pipelines and other anoxic systems.
2. Sulfur-Oxidizing Bacteria (SOB) MIC: SOB are typically aerobic bacteria that oxidize various sulfur compounds (e.g., elemental sulfur, thiosulfate, sulfides) to sulfuric acid (H₂SO₄).
3. Iron-Oxidizing Bacteria (IOB) MIC: IOB are typically aerobic or microaerophilic (requiring low oxygen) bacteria that derive energy by oxidizing ferrous iron (Fe²⁺) to ferric iron (Fe³⁺).
4. Acid-Producing Bacteria (APB) MIC: APB produce various organic (e.g., acetic, formic, lactic) or inorganic (e.g., sulfuric, nitric) acids as byproducts of their metabolism.
5. Methanogens MIC (Archaea): Methanogens are a group of Archaea (single-celled microorganisms distinct from bacteria) that produce methane (CH₄) as a metabolic byproduct. Some methanogens have been identified as contributors to MIC in anaerobic environments.

Besides these main categories, other microbial groups can also contribute to MIC, such as Slime-Forming Bacteria, Nitrate-Reducing Bacteria (BRB) and Manganese-Oxidizing Bacterial. However, above mentioned five are more prevalent in Oil and Gas industry. It’s important to note that in real-world systems, MIC is rarely caused by a single type of microorganism in isolation. Instead, complex microbial communities (biofilms) involving multiple groups often work synergistically, making detection and mitigation challenging.

The oil and gas industry is especially vulnerable to MIC for several reasons:

• Water Presence: Water, whether fresh, saltwater, or produced water (a byproduct of oil and gas extraction), is abundant in oil and gas operations. This provides the essential aqueous environment for microbial growth.
• Nutrient Availability: Hydrocarbons, production chemicals, and even corrosion inhibitors can serve as nutrient sources for various microbial communities.
• Stagnant Conditions: Dead legs, low-flow areas, and settled sediments in pipelines and tanks create ideal stagnant environments where biofilms can flourish without being dislodged by flow.
• Diverse Microbial Populations: Oil and gas systems harbor a wide array of microorganisms, including notorious culprits like Sulfate-Reducing Bacteria (SRB), Iron-Oxidizing Bacteria (IOB), and Acid-Producing Bacteria (APB), each contributing to unique corrosion mechanisms.

The Devastating Impact of MIC

The consequences of MIC are far-reaching and costly:

• Structural Integrity Threats: MIC can lead to localized pitting, crevice corrosion, and even stress cracking, significantly compromising the structural integrity of pipelines and vessels. This increases the risk of leaks, ruptures, and catastrophic failures.
• Increased Maintenance and Repair Costs: Detecting, monitoring, and mitigating MIC requires significant investment in specialized inspection techniques, chemical treatments (like biocides), and often, costly repairs or replacements of affected infrastructure.
• Production Losses: Equipment failures due to MIC can lead to unexpected shutdowns, reduced throughput, and significant production losses, impacting profitability.
• Environmental Hazards: Leaks and spills caused by MIC-induced failures can result in severe environmental contamination, leading to hefty fines, legal liabilities, and reputational damage.
• Safety Risks: The release of flammable or toxic substances due to MIC failures poses serious safety risks to personnel and surrounding communities.

Real-world examples underscore the severity of MIC. Past incidents, like significant methane leaks and crude oil spills, have been directly attributed to MIC, leading to billions of dollars in economic losses, environmental devastation, and even loss of life.

Conclusion

Microbiologically Influenced Corrosion is a persistent and costly challenge for the oil and gas industry, demanding vigilance and proactive strategies. By understanding the mechanisms behind MIC, embracing advanced detection technologies, and implementing robust prevention and mitigation measures, the industry can significantly reduce the risk of asset failures, protect the environment, and ensure the long-term integrity and safety of its operations. The invisible enemy may be tiny, but its impact is anything but small.

About Stress Engineering Services

Our SES materials department actively performs MIC identification through numerous laboratory projects. We leverage qPCR (quantitative polymerase chain reaction) in our corrosion lab—a DNA-based molecular microbiological method (MMM) that precisely quantifies total bacteria, total archaea, and specific microorganisms. This powerful tool provides a rapid and objective assessment of microbial populations, unlike traditional culture-based methods. For industries like oil and gas, qPCR is invaluable for understanding and managing MIC by assessing corrosion risks and optimizing mitigation strategies. It enables us to detect MIC-related microorganisms early, allowing for timely intervention and preventing expensive damage. Additionally, our SES corrosion engineering staff possesses hands-on experience in detecting MIC on metals through field inspection and analysis.