The oil well pipes in oil and gas fields, oil well pipes is including casing, tubing, drill pipe, drill collar and kelly.Domestic oil and gas fields of oil tube and pipe main show in bad environment is : high temperature and high pressure; high chloride ion content, high salinity high content of sulfur components such as carbon dioxide, hydrogen sulfide and elemental sulfur; high yields (erosion) by all of these factors and their interactions, and the high moisture content; oils and serious pipe corrosion.
Status of corrosion for oil wells
Tubing corrosion can be broadly divided into uniform corrosion and localized corrosion, one of the most severe corrosion perforation caused by localized corrosion to localized corrosion corrosion mechanism of transformation induced corrosion, crevice corrosion, intergranular corrosion and stress corrosion. Oil and Gas mining methods, the state of motion of the borehole fluid, oil and gas and the composition of the formation water and the nature of the liquid and well tubing and the outer annular space of the gas (or air) and the composition of the medium, the rate and distribution of the tubing and casing corrosion damage. important influence for no downhole packer gas wells, the outer wall of the tubing may be more serious than the internal corrosion. the tubing wall fluid is flowing, the condensate water is not easy to form a corrosion cell in the inner wall of the tubing adsorption, corrosion of the inner wall is lighter; The casing annulus packer, corrosive medium (saturated hydrogen sulfide and carbon dioxide) into and condensation in the tubing outer surface, attached to the tubing outer wall of the corrosion cell is formed, results in loose iron sulfide film is formed on the wall, a metal formed in contact with sulfide galvanic corrosion, in which the metal as the anode and the rapid destruction of the casing annulus placed the better performance of the packer production wells, corrosion inhibitor in the casing annulus relatively static space form a good protective film, the outer wall of corrosion is relatively light.
Oil well pipe protection technology
Lower cost of ordinary carbon steel tubing, but the frequent need to replace the tubing and snubbing. Reservoir damage, how to correctly predict the service life of ordinary carbon steel tubing, this protection method is a significant challenge. the use of corrosion-resistant alloy pipe anti-corrosion effect, within the validity period, without other supporting measures, no effect on the production operations of oil and gas wells, and the process is simple but high alloy steel pipe price, and therefore not suitable for domestic low-yielding Gas Field. Joined in corrosive environments, a small amount of corrosion inhibitor, and the metal surface can occur on the physical and chemical action, thereby significantly reducing the corrosion of metals. Note corrosion inhibitor does not need to change the nature of the metal member, and thus has economic adaptability strong and high efficiency for the tubing surface corrosion, can not replace the existing pipe using a dedicated inhibitor to control corrosion. injection of chemical protection, mainly in the following main issues: Corrosion Inhibitor effective mass concentrations were lower, the effective protection period is short; less initial investment, the cumulative investment cost is high; the actual corrosion environment is complex, poor adaptability; inhibitor dosing dosing device needs too much difficult to manage, not conducive to safe production through the appropriate process, inhibiting corrosion covering layer on the metal surface, metal and corrosive media, separated from the cover layer is mainly two categories Metallic and non-metallic coating for oil and pipe anti-corrosion coating technology used metal plating, coating of organic materials and chemical plating.
Post time: Dec-16-2020