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The corrosion of oil well tubing, casings, and downhole tools – commonly referred to as well corrosion – is largely influenced by the composition of the produced fluids and associated gases. The main factors that cause corrosion include CO2, H2S, and the composition of the produced water. 1. CO2 corrosion: The most typical characteristics of CO2 corrosion are localized pitting, ring-shaped corrosion, and platform-like pitting. Among them, tabletop pitting is the most severe form of corrosion. This type of corrosion has a high perforation rate; typically, the corrosion rate is 3–7 mm/year, and in oxygen-deficient conditions, it can reach 20 mm/year. Based on the level of CO2 partial pressure, it is generally possible to determine whether corrosion is present; if the partial pressure exceeds 0.2 MPa, corrosion occurs ； The partial pressure is between 0.05 and 0.2 MPa; corrosion may occur ； The partial pressure is less than 0.05 MPa, with no corrosion. 2. H2S corrosion: H2S corrosion can occur when oil well production fluids and associated gases contain H2S or sulfate-reducing bacteria. The corrosion characteristics of H2S are as follows: (1) The dissociation products of hydrogen sulfide, HS- and S2-, both promote corrosion. ⑵The properties of corrosion products formed under different conditions vary. At low temperatures, the formation of FexSy promotes corrosion, while at higher temperatures, the formed FeS inhibits corrosion. ⑶In addition to causing localized corrosion, H2S can also easily lead to sulfide stress cracking. In the corrosion of the vast majority of oil wells, the water content of crude oil and its composition play a decisive role. In the early stages of oilfield development, the water content is low, so corrosion in the oil wells is not severe. However, as the water content increases, corrosion of the downhole production tools and tubing strings in oil wells becomes increasingly severe.