How Important Is Cathodic Protection for Oil Well Casing

With the rapid development of the petroleum industry, severe corrosion of oil well casing, buried pipelines, and tank bottoms, especially oil well casing, has had a serious impact on oilfield production, development, management, and the environment. Corrosion occurs on both the inner and outer walls of oil and gas well casing, with internal corrosion being more severe.

Furthermore, in well sections with significant well deviation changes, mechanical damage from the tubing during operations accelerates corrosion and perforation of the oil well casing. Welding defects and thread gaps in the oil well casing welds can cause differences in the electrochemical properties of the casing surface, also leading to more severe corrosion damage. To address the corrosion problem of the inner wall of the oil well casing, bactericides and corrosion inhibitors are generally added to the annulus of the well, pH is adjusted, and oxygen-free sealing technology is used. In sulfur-containing oil and gas fields, low-strength oil well casing is selected.

To address the corrosion problem of the outer wall of the oil well casing, cathodic protection technology should be adopted. This is currently widely recognized by professionals in the corrosion prevention field, both domestically and internationally. Cathodic protection of oil casing is the most economical, reasonable, and effective technical measure to prevent soil corrosion of underground steel structures. It is a safe and mature anti-corrosion technology. Oil casing offers strong protection, is easy to install, and requires relatively low investment. This technology is increasingly widely used in the oil and gas, petrochemical, and municipal construction industries.

Catholic protection technology for oil casing is not only effective in preventing corrosion of newly built oil casing but also highly effective for existing old oil casing, extending its service life, reducing replacement frequency, and resulting in significant economic benefits.