YK6H井高压阀门腐蚀及防护对策

YK6H井为雅克拉凝析气田一口高温、高压、高产、高流速的凝析气井,该井油压30 MPa,油温80℃,回压8.0 MPa,回温60℃,流速6.5 m/s,CO2含量3.10%,CO2分压0.248 MPa,H2S质量浓度25 mg/m3,腐蚀环境复杂。YK6H井口和站外高压阀门多次发生法兰钢圈槽、本体腐蚀刺漏事件,造成频繁关井更换阀门,目前已累计更换高压阀门6套。根据YK6H高压阀门腐蚀现状,从阀门服役腐蚀环境、阀门材质、阀门加工工艺等方面进行阀门腐蚀行为分析,结果表明:阀门腐蚀主要是CO2冲刷腐蚀,电偶腐蚀、静电腐蚀和高流速在紊流、空蚀、冲击腐蚀等的影响加速了法兰金属槽的CO2腐蚀,加工工艺缺陷也是影响因素。针对阀门腐蚀影响因素,提出对应的防治措施。

Corrosion Behavior Analysis of YK6H Well High - pressure Valve and Countermeasures

YK6H well is a high - temperature, high - pressure, high - production, high - velocity condensate gas well. The eorrosion environment of the well is very complex because the well hydraulic pressure is 30 MPa, the oil temperature is 80℃ , the back pressure is 8.0 MPa, the back temperature is 60℃ , the velocity is 6.5 m/s and the CO2 content is 3. 10% , CO2 partial pressure is 0. 248, and H2S content is 25 mg/m3. YK6H wellhead and high - pressure valve suffered from a uumber of flange rim trough corrosion failure and corrosion leakages, and the well had to be shutdown to replace the valves. Up to now, six high- pressure valves have been replaeed. It is concluded by the analysis of corrosive service euvimnmen! of valve, valve material, valve manufacturing process, etc that the corrosion of the valve is mainly CO2 erosion currosion, galvanic corrosion and eleetrostatie enrrosion while the high flow velocity in the turbulent flow, the cavitation erosion, impingement corrosion etc have accelerated the CO2 corrosion of flange rim trough. In addition the detects in machining process is also an impact factor. The corresponding corrosion prevention measures are proposed based upon the impact factors of corrosion.