Corrosion behavior and countermeasures of buried elbows of gas production platform in coalbed methane field

In view of the leakage of buried elbow in a gas production platform of coalbed methane field in South Yanchuan due to corrosion perforation, analysis was carried out to the transmission medium, soil environment, corrosion products, and the metallographic structure of elbows and straight section of the buried pipeline. Meanwhile, the corrosion trend of the elbows and straight pipeline section was studied with electrochemical technology. The results show that the overflow of produced water from the coalbed methane wellhead leads to the increase of water content and chloride ion content in the soil, resulting in the increase of the buried environment corrosivity of pipeline and accelerating the failure of the anti-corrosion coating of the buried pipeline. Besides, the coarse material grains of elbows result in the higher electrochemical reactivity than that of the straight pipeline section, which leads to the serious local corrosion in the elbow areas. Therefore, comprehensive corrosion control countermeasures that combine the rectification of coalbed methane surface drainage pipeline with the enhanced repair of anti-corrosion coating and the cathodic protection of buried pipelines were put forward. Generally, the relevant results could provide reference for the safety management of gas production platform in coalbed methane field.