Key issues related to modelling of internal corrosion of oil and gas pipelines - A review

About a century ago, researchers first recognized a connection between the activity of environmental microorganisms and cases of anaerobic iron corrosion. Since then, such microbially influenced corrosion (MIC) has gained prominence and its technical and economic implications are now widely recognized. Under anoxic conditions (e.g., in oil and gas pipelines), sulfate-reducing bacteria (SRB) are commonly considered the main culprits of MIC. This perception largely stems from three recurrent observations. First, anoxic sulfate-rich environments (e.g., anoxic seawater) are particularly corrosive. Second, SRB and their characteristic corrosion product iron sulfide are ubiquitously associated with anaerobic corrosion damage, and third, no other physiological group produces comparably severe corrosion damage in laboratory-grown pure cultures. However, there remain many open questions as to the underlying mechanisms and their relative contributions to corrosion. On the one hand, SRB damage iron constructions indirectly through a corrosive chemical agent, hydrogen sulfide, formed by the organisms as a dissimilatory product from sulfate reduction with organic compounds or hydrogen ("chemical microbially influenced corrosion"; CMIC). On the other hand, certain SRB can also attack iron via withdrawal of electrons ("electrical microbially influenced corrosion"; EMIC), viz., directly by metabolic coupling. Corrosion of iron by SRB is typically associated with the formation of iron sulfides (FeS) which, paradoxically, may reduce corrosion in some cases while they increase it in others. This brief review traces the historical twists in the perception of SRB-induced corrosion, considering the presently most plausible explanations as well as possible early misconceptions in the understanding of severe corrosion in anoxic, sulfate-rich environments.

Corrosion of Iron by Sulfate-Reducing Bacteria: New Views of an Old Problem

In order to ensure smooth and uninterrupted flow of oil and gas to the end users, it is imperative for the field operators, pipeline engineers, and designers to be corrosion conscious as the lines and their component fittings would undergo material degradations due to corrosion. This paper gives a comprehensive review of corrosion problems during oil and gas production and its mitigation. The chemistry of corrosion mechanism had been examined with the various types of corrosion and associated corroding agents in the oil and gas industry. Factors affecting each of the various forms of corrosion were also presented. Ways of mitigating this menace with current technology of low costs had been discussed. It was noticed that the principles of corrosion must be understood in order to effectively select materials and to design, fabricate, and utilize metal structures for the optimum economic life of facilities and safety in oil and gas operations. Also, oil and gas materials last longer when both inhibitors and protective coatings are used together than when only batch inhibition was used. However, it is recommended that consultations with process, operations, materials, and corrosion engineers are necessary in the fitness of things to save billions of dollars wasted on corrosion in the oil and gas industries.

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Corrosion problems during oil and gas production and its mitigation

Evolution of dissolution processes at the interface of carbon steel corroding in a CO2 environment studied by EIS

Critical review: Microbially influenced corrosion of buried carbon steel pipes

http://www.icmt.ohio.edu/documents/Journals2009/The%20Effect%20of%20Temperature%20and%20Ionic%20Strength%20on%20Iron%20Carbonate%20(FeCO3)%20Solubility%20Limit_Sun_2009.pdf

The effect of temperature and ionic strength on iron carbonate (FeCO3) solubility limit

Kinetics of iron carbonate layer formation in carbon dioxide corrosion has been investigated using a direct method—the corrosion layer weight-change method. The experiments were conducted in a glass cell at the temperatures from 60°C to 90°C, within an iron carbonate supersaturation range from 10 to 350. It was found that the calculated results obtained by the previous kinetics expressions, which were based on the traditional dissolved ferrous ion concentration change method, are one to two orders of magnitude higher than the experimental reaction rates obtained in the present study. Based on the new data, a more appropriate equation is developed to describe iron carbonate layer growth on the steel surface. The experimental results further suggest that the main source of the ferrous ions, which are involved in the formation of the protective iron carbonate layer, is the iron dissolution process. It has been clearly demonstrated that the formation of iron carbonate is directly related to the condi...

Kinetics of Corrosion Layer Formation. Part 1-Iron Carbonate Layers in Carbon Dioxide Corrosion

A Mechanistic Model Of H2S Corrosion Of Mild Steel

A major problem in the oil and gas industry is corrosion in sour (or H2S-containing) environments. Low concentrations of H2S act to inhibit corrosion, because of the formation of a protective iron sulfide film/scale on steel surfaces; large concentrations can lead to pitting, severe localized corrosion, and catastrophic failure. Therefore, the solubility and hydrothermal stability of iron sulfides is particularly relevant to corrosion. To understand the mechanisms that are associated with the hydrothermal formation of iron sulfides, it is important to reliably estimate equilibrium constants for all the reactions involved, including those for the dissolution and dissociation of H2S. In this study, equations for determining the equilibrium constants that are related to the solubility of mackinawite are evaluated, and the most appropriate expressions are described. Also, the most relevant expressions for the solubility of H2S and for the first dissociation constant of H2S are reviewed. It is recommended that...

Equilibrium Expressions Related to the Solubility of the Sour Corrosion Product Mackinawite

A mechanistic model of uniform hydrogen sulfide (H2S) and hydrogen sulfide/carbon dioxide (H2S/CO2) corrosion of mild steel is presented that is able to predict the rate of corrosion with ...

Wei Sun

Papers

The effect of temperature and ionic strength on iron carbonate (FeCO3) solubility limit

Kinetics of Corrosion Layer Formation. Part 1-Iron Carbonate Layers in Carbon Dioxide Corrosion

A Mechanistic Model Of H2S Corrosion Of Mild Steel

Equilibrium Expressions Related to the Solubility of the Sour Corrosion Product Mackinawite

A Mechanistic Model of Uniform Hydrogen Sulfide/Carbon Dioxide Corrosion of Mild Steel