海上钻井管线腐蚀原因分析和防治对策

调查和分析了南海某油田钻井管线典型腐蚀案例,得出结论为:流速导致磨损腐蚀、CO2腐蚀和高腐蚀性井下流体共同造成了钻井管线的严重损伤,其中流速是最主要的因素,它们在内部空间几何形状变化剧烈的管子内形成剧烈紊流并造成严重磨损腐蚀.关键控制方法是保持井下实际流速低于临界流速.讨论了流体含沙量对临界流速的影响,并提出其他可以采用的降低腐蚀/磨损的防护方法.

Analysis of the Cause of Corrosion and Preventive Meusure for Offshore Drilling Tubing

Typical corrosion cases of drilling tubing in offshore oilfield located at South China Sea were investigated and analysed.The conclusions were that the flow induced erosion/corrosion and CO2 corrosion worked together with high corrosive downhole fluid to cause severe damage of drilling tubing.Among the factors,the high flowing rates are primary,which form high level of flow turbulence and caused severe erosion-corrosion damage to the inside walls of tubing with abrupt geometric changes in the inside space.A key control method is to keep the real downhole flowing rates below the cricital folwing rate,vt.The effects of the sand content in the fluid on vt were discussed.The alternative protective methods were also proposed to reduce the corrosion/errosion damage.