Common anticorrosion methods of oil casing pipe

　　Cement sealing and anti-corrosion technology

　　In the early stage, the main reason of casing damage is that the cement return height is not enough, which leads to the outer water layer not completely sealed, and the corrosive gas in the water layer erodes the casing surface, causing corrosion. Therefore, in the 1980s, the strategy of improving cement return height was put forward to increase the corrosion resistance of casing. Through this technology, the casing corrosion degree is reduced, but the casing corrosion is not completely prevented, so the anti-corrosion performance of casing is not improved from the root [1].

　　Use corrosion-resistant alloy pipe

　　Since 2000, the anti-corrosion scheme of offshore API-5CT Carbon Steel Seamless Casing Pipe has been seeking solutions from the aspect of materials, so as to improve the anti-corrosion performance of oil casings and thoroughly solve the corrosion problem of oil casings. In recent years, a set of anticorrosive charts suitable for offshore oil and gas field casings has been developed based on the evaluation of 1Cr, 3cr, 9Cr, 13Cr and other CR containing pipes under certain temperature and pressure conditions and corrosive gas conditions through laboratory experiments.

　　Corrosion inhibitor injection

　　From the completion process, if the formation contains corrosive gas, chemical anti-corrosion agent will be added to the well fluid to prevent scale, wax and corrosion. Therefore, the chemical method is also a conventional method at home and abroad. According to the different conditions of oil and gas fields, the corrosion inhibitor can be injected intermittently or continuously for corrosion prevention, and the injection amount also varies according to the corrosion environment of oil and gas fields. Due to the continuous need of inhibitor addition, on the one hand, the cost is high, and on the other hand, it will have a certain impact on the field production.