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Research on tubing material selection for preventing corrosion in high sour gas well under existence of bacteria corrosion

Lingfeng LI, Jian Xiong

The corrosive attack of material that is caused or promoted by the life activity of bacteria is known as bacteria corrosion. For high sour natural gas wells, formation water may possibly contain sulfate-reducing bacteria (SRB), iron bacteria, sulfur bacteria, and so on, which lurk in formation water and rock. The most common microbiological corrosion in high sour natural gas wells is sulfate-reducing bacteria corrosion.Material selection of tubing for preventing corrosion are very important factors of gas production system life. In order to ensure the long-term development of high sour gas well under existence of bacteria corrosion, this paper mainly study the material selection of tubing for preventing corrosion in high sour gas well under existence of bacteria corrosion. For material selection, traditional method is using sulfur-resistant steels. This paper proposes a new option: using corrosion-resistant alloy. By studying, traditional sulfur-resistant steels in high sour gas wells under existence of bacteria corrosion may have severe corrosion. For high sour gas wells under existence of bacteria corrosionwith high hydrogen sulfide and carbon dioxide content, the new option(selecting corrosion-resistant alloy) is a goodmeasure.By takingCY-T gas field as an example, this paper optimizes the material selection. By corrosion coupon test and galvanic corrosion test, the experiment results showthat there have serious galvanic corrosion and electrochemical corrosion for the traditional sulfur-resistant steel. Despite the high cost, the new option(selecting corrosion-resistant alloy) has long service life, and has no need for adding corrosion inhibitor. For high-productivity and high sour gas wells under existence of bacteria corrosion, the newoption(selecting corrosion-resistant alloy) is an effective and economic corrosion prevention measure. For on-the-spot application, the study above has a good practicality, and can provide reference for the similar high sour gas wells under existence of bacteria corrosion.