Corrosion Behaviour of Titanium Alloy and Carbon Steel in a High-Temperature, Single and Mixed-Phase, Simulated Geothermal Environment Containing H2S, CO2 and HCl

Abstract

The corrosion behaviour of a new titanium-based alloy, with nickel, molybdenum and zirconium as the main alloying elements, was studied in a simulated geothermal environment at various phase conditions of a corrosive fluid. Corrosion testing of carbon steel was also conducted for comparison. Both materials were tested at an elevated temperature between 180 and 350 °C and at a 10 bar gauge pressure in H2O containing HCl, H2S, and CO2 gases with an acidic condensate of pH = 3. The study found that the titanium alloy demonstrated good corrosion resistance in a single- and multiphase geothermal environment. In the testing volume, where the boiling of testing fluid occurred, the carbon steel was prone to localized damage of oxide, sulphide and chloride corrosion products. In the superheated testing volume, a homogeneous oxide corrosion layer was observed on the carbon steel. In the testing volume where condensation of the testing fluid occurred, a sulphide layer with an oxide sublayer was formed on the carbon steel.

Addressing Hydrogen Sulfide Corrosion in Oil and Gas Industries: A Sustainable Perspective

“…Titanium and its alloys exhibit exceptional resistance to corrosion induced by H 2 S, especially in acidic environments, thanks to the development of a protective surface layer made of TiO 2 in various corrosive settings [102]. In a study by Thorhallsson and Karlsdottir, 2021 [102], a simulated high-temperature geothermal environment ranging from 180 to 350 • C, with a gauge pressure of 10 bars, was employed. This environment comprised gases such as HCl, H 2 S, and CO 2 , alongside an acidic condensate with a pH of 3.…”