The oil industry has used 13 Chromium (13Cr) materials in oil and gas wells for many years. As wells are drilled deeper, the production environments become more aggressive, primarily due to high-temperature and high-pressure conditions, and sweet/sour gas production. These conditions present a challenge to tubular products. To meet industry demands, the tubular manufacturers have developed various chemically enhanced 13Cr materials for these applications. These tubular materials also challenge the corrosion inhibitor technology applied in acid stimulation fluids. There are many publications related to acidizing wells completed with 13Cr tubulars; however, regarding corrosion behavior of enhanced 13Cr materials in stimulation fluids, very little information has been published.
This paper presents results of acid corrosion tests performed on various 13Cr samples from two manufacturers at temperatures from 180°F to 312°F (82-156ºC) and from 6 to 30 hours of exposure. In addition, the acids were varied from acetic acid and hydrochloric acid to systems with hydrofluoric acid. The 13Cr samples ranged in yield strength from 85 to 110 ksi. Results indicate that corrosion behavior of enhanced 13Cr in acids can be completely different from that of 13Cr depending on an inhibitor package applied, and that strength of the material plays a significant role in corrosion behavior. Also, the data shows that some inhibitor packages typically used for 13Cr do not provide adequate corrosion protection on enhanced 13Cr materials.