抗盐水泥浆腐蚀钻杆研制与应用

R&D of Anti-brine Mud Corrosion Drill Pipe

分析了盐水泥浆腐蚀钻杆的表面形貌、腐蚀产物成分、相结构,并结合盐水泥浆成分分析了钻杆腐蚀的原因,根据腐蚀原理设计了抗盐水泥浆腐蚀高Cr钻杆钢的成分,研究了热处理工艺对钻杆钢组织和性能的影响.结果表明:钻杆表面腐蚀产物主要是氧化物,盐水泥浆中高的碱度和Cl^(-)、K^(+)等导致钻杆发生点蚀;钻杆钢经560~570℃回火后可获得良好的强韧性配合;在相同盐水泥浆腐蚀条件下,抗盐水泥浆腐蚀钻杆的腐蚀速率相比于API标准G105钻杆降低60%以上,能够满足盐水泥浆环境下的安全钻探需求,解决了钻杆在盐水泥浆环境下的过早腐蚀失效问题.

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.