CO2和H2S共存环境下井筒腐蚀主控因素及防腐对策——以塔里木盆地塔中Ⅰ气田为例

针对塔中Ⅰ气田天然气中CO2、H2S共存的特点,研究该腐蚀环境下管材腐蚀规律及防腐对策。通过5因素5水平正交实验,分析CO2压力、H2S压力、温度、Cl离子浓度及含水率这5个因素对抗硫油管腐蚀速率的影响程度,确定塔中Ⅰ气田腐蚀环境下的腐蚀主控因素为CO2压力。选择普通抗硫油管+缓蚀剂作为塔中Ⅰ气田油管的防腐对策,根据腐蚀主控因素筛选复配了适用于塔中Ⅰ气田腐蚀环境的缓蚀剂YU-4。该防腐工艺在塔中Ⅰ气田12口井中进行了应用,取得了显著的抗腐蚀效果,腐蚀速率达到防腐要求,其中TZ83井油管平均腐蚀速率由1.23 mm/a降至0.025 mm/a;TZ623井油管平均腐蚀速率由0.370 mm/a降至0.016 mm/a。

Major corrosion factors in the CO2 and H2S coexistent environment and the anti- corrosion method: Taking Tazhong I gas field, Tarim Basin, as an example

Anti-corrosion techniques are studied to deal with the CO2 and H2S coexistent environment of the TazhongⅠgas field.Orthogonal experiment with five different factors and levels is carried out to compare the influence of the factors on the corrosion rate of the sulfur resistance tubing.These five factors are pressure of CO2,pressure of H2S,temperature,content of Cl,and water cut.It is found that CO2 pressure is the major corrosion factor.The combination of sulfur resistance tubing and corrosion inhibitor is selected as the anti-corrosion method and the proper corrosion inhibitor named YU-4 is designed according to the result of orthogonal experiment.This anti-corrosion method was used in 12 wells of the Tazhong I gas field,achieving good results.The average corrosion rate of Well TZ83 decreased from 1.23 mm/a to 0.025 mm/a and the corrosion rate of Well TZ623 decreased from 0.370 mm/a to 0.016 mm/a.