Hydrogen Sulfide Corrosion in Oil and Gas Industries 

Pipelines play a crucial role in the oil and gas sector by facilitating the transportation of products to treatment facilities, storage depots, and refinery complexes. Given that these pipelines transport valuable and hazardous substances, any potential failure carries significant financial and environmental consequences, including the risk of catastrophic economic losses and threats to human life. Failures may arise from various factors, including corrosion (external, internal, and stress cracking), mechanical issues (such as material, design, and construction faults), third-party activities (accidental or intentional), operational problems (malfunctions, insufficiencies, disruptions of safeguarding systems, or operator errors), and natural phenomena (such as lightning strikes, floods, or land shifts).

The distribution of failures over 15 years (1990–2005) is illustrated. Corrosion is the primary contributing factor, accounting for 46.6% of failures in natural gas pipelines and 70.7% in crude oil pipelines. A corrosion cost assessment conducted by a reputable oil and gas corporation revealed that in the fiscal year 2003, expenditures for corrosion amounted to approximately USD 900 million. The global expense attributed to corrosion in the oil and gas sector stands at approximately USD 60 billion. In the United States alone, documented corrosion-related costs in such industries reach USD 1.372 billion. Furthermore, considering the increasing demand for energy sourced from oil and gas and the associated concerns, worldwide corrosion expenses within the industry are expected to continue to rise. Hence, there is a critical need for proactive risk assessments that balance cost-effectiveness and safety.

Ensuring the integrity of pipelines is paramount for safe operations, environmental preservation, and the functionality of major production assets. Corrosion poses a serious threat, both externally and internally. External corrosion can result from factors such as oxygen and chloride in the external environment [6]. In contrast, internal corrosion may stem from substances such as hydrogen sulfide (H2S), carbon dioxide (CO2), and organic acids present in the production fluid. Unmonitored and uncontrolled pipeline corrosion can lead to leaks and catastrophic failures. Internal corrosion has been a significant concern, constituting approximately 57.4% and 24.8% of corrosion failures in crude oil and natural gas pipelines, respectively . Addressing internal corrosion is imperative for maintaining industry integrity and safety.

In the oil and gas sector, corrosion is typically categorized into two primary types: sweet and sour corrosion, prevalent in environments characterized by elevated partial pressures of H2S and CO2 (PH2S and PCO2). These particular forms of corrosion represent significant challenges within the industry. Corrosion is further categorized into three regimes based on the ratio of PCO2 to PH2S: sweet corrosion (PCO2/PH2S > 500), sweet–sour corrosion (PCO2/PH2S ranging from 20 to 500), and sour corrosion (PCO2/PH2S

Critical factors influencing corrosion include PH2S and PCO2 levels, as well as temperature and pH values. These variables significantly affect the dissolution of corrosive gases, thereby influencing the rate and mechanism of corrosion product formation in sweet and sour environments. Temperature accelerates chemical reactions and increases gas solubility, impacting corrosion rates. pH levels determine environmental acidity or alkalinity, with low pH accelerating corrosion and high pH potentially triggering localized corrosion mechanisms. Dissolved CO2 and H2S gases generate corrosive acids in water, reacting with metal surfaces to form less protective compounds, thereby hastening corrosion. Sweet corrosion typically involves the creation of metal carbonates (MeCO3), while sour corrosion involves various metal sulfide formations.

In the oil and gas sector, material failures resulting from corrosion in both sour and sweet environments pose various safety, economic, and environmental challenges. Figure 2 shows the relative contribution of various forms of corrosion failures throughout the 1970s. Sour corrosion induced by H2S is identified as the primary cause of corrosion-related malfunctions in this industry, with its prevalence steadily escalating over time. Proactively addressing sour corrosion and instituting preventive measures are imperative for managing the associated risks in petroleum industries.

Managing and processing substances containing H2S pose significant challenges in the oil and gas sector. Understanding the intricacies of H2S corrosion is imperative, as it poses a substantial threat to equipment and infrastructure, elevating the risk of structural failure and potential accidents. This type of corrosion evidently diminishes the lifespan of equipment, necessitating costly maintenance or replacement endeavors. Moreover, it impedes operational efficiency, leading to decreased output and heightened energy consumption levels.

Comprehending and addressing the challenges posed by H2S corrosion within such industries yields noticeable advantages. Safety measures are strengthened by preventing breakdowns and maintaining equipment, and the possibility of accidents and environmental consequences is reduced. This strategy also prolongs the lifespan of equipment, diminishing the need for costly replacements and minimizing the downtime required for repairs. Additionally, it improves operational efficacy by guaranteeing effective and consistent procedures, reducing energy consumption, and reinforcing flow reliability.

Exploring areas for further investigation, including advanced coating technologies, new materials, electrochemical processes, and emerging technologies, is essential. The development of innovative approaches, such as continuous monitoring systems and predictive modeling, shows the potential to enhance precautionary measures. Applying advanced artificial intelligence and advanced analytics in management, prediction, and controlling corrosion is an emerging field that deserves further exploration.

Vigor's R&D department has successfully developed a new composite (fiberglass) bridge plug resistant to hydrogen sulfide. It has demonstrated excellent performance in both lab tests and customer field trials. Our technical team is fully equipped to customize and produce these plugs according to specific site requirements. For inquiries about Vigor's bridge plug solutions, reach out to our team for tailored products and exceptional service quality.

For more information, you can write to our mailboxinfo@vigorpetroleum.com&marketing@vigordrilling.com