R&D of Anti-brine Mud Corrosion Drill Pipe

Analyzed are the surface appearance,the composition of the corrosion products and the phase structure of the anti-brine mud drill pipe.And based on the composition of the saline mud the causes for corrosion of the drill pipe are also analyzed.According to the corrosion principle,the chemical composition of the hi-Cr anti-saline mud corrosion drill pipe is designed,and the influence by the heat treatment process on the steel microstructure and properties of the drill pipe is studied as well.It is identified that the main product from the surface corrosion of the drill pipe is mainly the oxide,and it is the alkalinity in the saline mud and Cl^-,and K⁺etc.which lead to pitting corrosion of the drill pipe;after tempered at 560~570℃,the drill pipe steel has well-mated strength-toughness;and given the corrosiveness of the saline mud is the same,the corrosion ratio of the anti-saline mud corrosion drill pipe is at least 60% lower than that of the API G105 drill pipe,therefore the former can meet the requirement for safe drilling operation under saline water mud condition,and thus the problem of early corrosion-caused failure of the drill pipe as servicing under the saline water mud condition is solved.