This paper describes the results of a laboratory study evaluating corrosion resistance of a tantalum
surface alloy on stainless steel and multiple corrosion resistant alloys in a laboratory simulation of two
deep well acidizing environments. Acidizing is a common practice in oil production where wellstimulation
acids are pumped through tubular goods into an oil reservoir in order to remove formation
damage, increase porosity in the formation, and clean deposits from tubulars. These acids can cause
high corrosion rates on nearly every alloy utilized in production. General and localized corrosion
susceptibility of alloys 316L (UNS S31603), Ti 6-4 (UNS R56400), Ti 6-2-4-6 (UNS R56260), C276
(UNS N10276) and a tantalum (Ta) surface alloy on 316L in high temperature mineral and organic
acids was assessed. The two acidizing environments that were studied included 10% acetic acid and a
mixture of 10% acetic acid and 10% hydrochloric acid with 15 psia (0.1 MPa) hydrogen sulfide (H2S) at
450 °F (232 °C). The paper also presents the possible use of tantalum surface alloys on commonly
employed steels in the oilfield for improved resistance to extreme environments where nickel and
titanium alloys fare poorly.
Key words: Acidizing, HCl, Acetic Acid, Ti 6-4, Ti 6-2-4-6, C276, Tantalum, Surface Alloy