Abstract
The ability to detect early corrosion onset in real time before structural integrity is compromised can have a significant impact on preventing catastrophic failures of components resulting from corrosion. High durability is required for corrosion sensors in extreme service conditions such as high temperature high pressure in subsurface wellbores. We have previously demonstrated a distributed corrosion sensor for early corrosion detection with the use of proxy materials integrated with the optical fiber sensing platform at ambient conditions. In this work, an optical fiber sensor functionalized with a thin-film coating of carbon steel X65 was tested at 80 °C to study corrosion monitoring capability and sensor durability. The X65 carbon steel thin film was sputter-deposited onto the optical fiber as the corrosion proxy material. The sensor was tested in CO2-saturated and N2-saturated 3.5 wt% NaCl solutions. When exposed to the corrosive solutions, broad-band light absorption of the metallic thin film decreased as the film got thinner; therefore, the light transmission through the optical fiber increased over time. The results demonstrate that X65 thin-film coated optical fiber sensor has successfully detected a higher corrosion rate in the CO2-saturated NaCl solution than that in the N2-saturated NaCl solution at 80 °C.
