P110SS Casing Corrosion Rate Testing and Service Life Prediction

In order to effectively inhibit the casing corrosion process and extend the service life of downhole casing, P110ss corrosion-resistant alloy steel casing has been applied on a large scale in well completion operations in a block of Southwest oil and gas field. In recent years, the risk of casing corrosion failure is easily triggered by the direct exposure of the tubing column to H2S-containing gas due to the leakage of protective fluid. In order to realize the residual strength analysis and life prediction of corrosive casing in this gas field, this paper measured the corrosion rate of P110ss casing in 7% H2S content is about 0.1282 mm/a through corrosion experiments, and predicted the service life of corrosive casing in hazardous layer position by using a combination of theoretical calculation and numerical simulation. The results show that: multiple pitting pits with edge distance greater than 1mm can be replaced by single pitting pits when calculating casing stress; the corrosion life of two different sizes of casing under uniform corrosion is 8 and 14 years respectively, and the service life of casing under pitting corrosion is less than that of uniformly corroded casing. The results of the study can provide effective reference for the prevention and control of corrosion casing in this area.