With the rapid development of the petroleum industry, the serious corrosion of oil well casings
, buried pipelines, tank bottoms, especially oil well casings inside the oilfield has seriously affected the production, development, management and environment of the oilfield. Corrosion exists in the inner and outer walls of the oil and gas well casing, and the internal corrosion is serious.
In addition, in the well section where the inclination of the well varies greatly, the mechanical damage of the casing to the casing accelerates the corrosion perforation of the casing; the welding defects existing in the weld, the gap of the thread and the like are likely to cause differences in the electrochemical performance of the surface of the steel pipe. It also causes corrosion damage to be more serious. To solve the corrosion problem of the inner wall of the oil well casing, generally add a bactericide, a corrosion inhibitor, a mediation PH value, a closed oxygen barrier technology in the annular space of the oil well, and select a low-strength oil casing in the sulfur-containing oil and gas field.
To solve the corrosion problem of the outer wall of the oil well casing, cathodic protection technology should be adopted. At present, this has been recognized by people at home and abroad. To prevent soil corrosion to underground steel structures, cathodic protection is the most economical and effective technical measure. Cathodic protection is a safe and mature anti-corrosion technology. It has the characteristics of strong protection, simple construction and low investment. This technology is increasingly used in oil and gas, petrochemical, municipal construction and other departments.
Cathodic protection technology can not only prevent the corrosion of newly built oil well casings, but also be effective for the old oil well casings that have been built. It can prolong the service life, reduce the number of replacements, and the economic benefits are very obvious.