陕北气田气井腐蚀速率影响因素及规律

Factors and Rules Affecting Gas Well Corrosion Rate in Shanbei Gasfield

目的选择恰当、高效防腐对策以提高气田开发经济效益,保证气井安全生产。方法对陕北某气田的水质进行全面分析,并以通入饱和CO_2的气田气井产出水作为腐蚀介质,通过静态失重法探讨温度、矿化度、体系酸碱度、水介质中CO_2含量、H_2S含量、溶解氧含量、HCO3含量、Cl^-含量对设备管道腐蚀性的影响及其腐蚀规律。结果陕北某气田的气井产出水矿化度约为50 000 mg/L,且Cl^-、HCO3-含量偏高,水样呈弱酸性,p H值约6.5;腐蚀速率随水介质中CO_2含量、H_2S含量、溶解氧含量、HCO3-含量、Cl^-含量增加均呈增加趋势,在50℃时最大达到0.352 mm/a,p H值为7时最小为0.250 mm/a。结论陕北某气田设备管道的腐蚀主要表现为O_2腐蚀和CO_2腐蚀。

Objective To choose appropriate and efficient anti-corrosion measures so as to improve economic benefit and ensure safety of oilfield production. Methods In the paper,water quality of Shanbei gasfield was analyzed and the gas field water from gas well replenished with saturated CO_2 was taken as corrosive medium. The influences of temperature,salinity,systematic p H,CO_2 content and H_2 S content in the water,dissolved oxygen content,HCO3-content and Cl^-content on the equipment pipeline corrosion and the corrosion pattern were discussed by static weight-loss method. Results The water from Shanbei gasfield had the salinity reaching about 50 000 mg/L,Cl^-and HCO3-contents were relatively high,the water sample was weak acidic,the p H value was around 6. 5. The corrosion rate increased with the increasing in contents of CO_2,H_2 S,dissolved oxygen,HCO3-and Cl^-in the water medium,the corrosion rate reached the maximum 0. 352 mm/a at 50 ℃ and the lowest 0. 250 mm/a when the p H value was7. Conclusion Corrosion of equipment pipelines of Shanbei gasfield is mainly O_2 corrsion and CO_2 corrsion.