Comparative Study on Tribology Behavior of Titanium Alloy Drill Pipe Under Simulated Working Conditions in Ultra-deep Well Drilling Conditions

Titanium alloy has become a promising candidate material for oil country tubular goods (OCTG) and offshore components in rigorous service environment, owing to its high specific strength, low density, low elastic modulus, excellent toughness, fatigue and corrosion resistance. However, there is a lack of research on the friction and wear properties of titanium alloy drill pipes under ultra-deep drilling conditions, and the comparison research on the tribology performance and mechanism of titanium alloy drill pipes and steel drill pipes is few. In this work, the friction and wear properties of three kinds of titanium alloy drill pipes and steel drill pipes were compared and analyzed through hardness test, impact wear test, reciprocating friction test, simulated condition wear test and microscopic analysis in simulating ultra-deep well conditions, and the wear mechanism of titanium alloy drill pipes under drilling conditions were also investigated. The results show that the impact and wear resistance of titanium alloy drill pipes is lower than that of steel drill pipe materials, especially the impact resistance of titanium alloy drill pipe materials under medium-frequency impact. In the air reciprocating wear test, the friction coefficient of titanium alloy drill pipe is lower than that of steel drill pipe. When titanium alloy drill pipe is worn against rock, it is a typical abrasive wear mechanism, and it is typical adhesive wear when it is worn against steel pipe. Under the simulated working condition of drilling fluid, the friction coefficient of titanium alloy drill pipe is significantly lower than that in air, and the friction coefficient of titanium alloy is the lowest when friction with rock under water-based drilling fluid conditions, and the wear resistance is the strongest, which is due to the fact that it is easier to form a dense passivation film with a lower friction coefficient on the surface of the titanium alloy in the water-based drilling fluid. It is recommended to use water-based drilling fluid when drilling with titanium alloy drill pipes. However, because the wear of titanium alloy drill pipes under working conditions is still not as good as that of steel drill pipes, the next step is to conduct surface treatment on titanium alloy drill pipes to improve the wear resistance of titanium alloys. © 2023 Rare Metals Materials and Engineering Press. All rights reserved.