Development of an electrochemically integrated SR-GIXRD flow cell to study FeCO₃ formation kinetics

Area of Science:

• Materials Science and Engineering
• Electrochemistry
• Corrosion Science

Background:

• Corrosion product formation on carbon steel in CO2-rich brines is a significant challenge in oil and gas production.
• Understanding the kinetics of corrosion product precipitation is crucial for developing effective mitigation strategies.
• Existing methods often lack the in situ resolution to capture early-stage precipitation events and their impact on corrosion rates.

Purpose of the Study:

• To develop and present an electrochemically integrated Synchrotron Radiation-Grazing Incidence X-Ray Diffraction (SR-GIXRD) flow cell.
• To investigate the nucleation and growth kinetics of corrosion products, specifically FeCO3, on carbon steel under simulated production conditions.
• To correlate in situ corrosion rates with the formation of crystalline corrosion products.

Main Methods:

• Design and implementation of a novel SR-GIXRD flow cell capable of high flow velocities (up to 2 m/s) and temperatures (>80°C).
• Simultaneous in situ monitoring of electrochemical response (linear polarization resistance) and surface diffraction patterns during corrosion experiments.
• Ex situ characterization using scanning electron microscopy (SEM) for validation of in situ findings.

Main Results:

• The developed flow cell successfully enabled in situ SR-GIXRD measurements of corrosion product formation on X65 carbon steel in CO2-saturated brine.
• Iron carbonate (FeCO3) nucleation was detected significantly before any measurable inhibitive effect on the general corrosion rate.
• In situ observations were corroborated by ex situ SEM, confirming the formation of an FeCO3 layer and identifying FeCO3 as the sole crystalline phase.

Conclusions:

• The integrated SR-GIXRD flow cell is a powerful tool for studying real-time corrosion product formation and kinetics.
• FeCO3 precipitation occurs and influences corrosion rates at later stages than its initial nucleation.
• This technology provides critical insights into the mechanisms of carbon steel corrosion in CO2-environment, aiding in the development of better corrosion control strategies for the oil and gas industry.