“…The Tarim Basin, where exists abundant natural gas in the depth between 6,500-8,000 m, has been constructed with 52 wells in Kuqa from 2012 (Liu et al, 2019a). Due to the high pressure , high temperature (170 °C-190 °C), and complex corrosive medium, the corrosion issues of highly dense brine-based completion fluids on tubing and casing materials in ultra-deep high-temperature wells have become a research hot spot in the course of oil and gas exploitation (Yue et al, 2020a;Li et al, 2020;Zhao et al, 2020). The considered competition fluids are mainly the bromine salt completion fluids (KBr, ZnBr 2 , and CaBr 2 ) (Liu et al, 2014;Liu et al, 2019b) and/or formate brines (NaCOOH, KCOOH, and CsCOOH) (Bungert et al, 2000;Leth-Olsen, 2004;Zhu et al, 2011b).…”