Low Cr (3 to 5%) bearing steels have been developed and used in CO2 environment as materials to meet "Fitness for Purpose". However, the SSC and SCC resistance of low Cr bearing steel have not been clarified. This paper presents the effect of carbon content, microstructure, and tempering temperature on the SSC and SCC resistance as well as CO2 corrosion resistance of low Cr steel (3%Cr steel).
Nitrogen-based model CI compounds with different functional groups and sulfur containing synergist molecules were selected for mechanistic study. The oil-water partitioning behavior and corrosion performance of these model compounds were investigated and correlated to their chemical structures in a variety of sweet corrosion environments.
The Supercritical Carbon Dioxide Corrosion Test Facility is equipped with 3 high-temperature, high-pressure vessels and a gas-phase Fourier transform infrared spectrometer (FTIR) for simultaneous in situ monitoring of key contaminants. This paper outlines the capabilities of this new National Institute of Standards and Technology facility.
A fit for purpose qualification of new corrosion inhibitors was carried out for in a gas and condensate field. The depth of production well is 4,500 m and the bottom hole temperature and pressure are 180ºC and 50 MPa respectively. The methodology and result of the inhibitor evaluation under a sweet condition was summarized. Two brands of corrosion inhibitors had been used each for production tubing and flowline in the field. New corrosion inhibitors were evaluated for the both applications. The corrosion inhibitor efficiency for high shear service and the adhesion tendency were evaluated with a rotating cage autoclave and a dip and drip experiment respectively. In order to evaluate the tendency of emulsion forming, oil, brine and an inhibitor were poured into a centrifuge tube and it was shaken intensely. Gas chromatograph - mass spectrometer (GC-MS) and Fourier transform infrared spectroscopy (FT-IR) were studied to measure the residual amount of inhibitor. Finally, the field trial was conducted with a new inhibitor. The new inhibitor was adopted successfully for the both services. The risk of emulsion forming became lower because the mixing of two brands of inhibitors was avoided. Reducing the number of the chemicals contributed to reduction of the operation cost too.