Large Gas Field Casing Corrosion Behavior And Protective Measures

The CO₂ corrosion behaviors of casing steels products were studied by corrosion weight-loss method in a simulation environment with high temperature and high pressure. SEM and XRD were used as accessorial surface analytical method. The results of rearsch is the base of Corrosion protection. Further, the efects on the corrosion rate of the surface appearance structure and constitution of corrosion scale under different temperature and partial pressure was studied.According to Hangs the piece experiment through the static state, in the research oil field formation water the salts single factor as well as other factors to affect casing steels products N80 steel, A3 steel, 20# steel corrosion situation, and carries on the contrast analysis to test the results. Then discovers using the Gray Relation Analysis method corrodes the influence big factor to the casing steels, in order to take the effective protective measure.After studied the material CO₂ corrosion behavior, the corrosion mechanism foundation, the union oil field existing application environment, proposed a series of protective measure, such as the reasonable selection, the superficial modified technology, the corrosion inhibitor application, the pulse electric current cathodic protection technology, and used the corresponding electrochemistry test research to the different protective corrosion measure, and provided the corresponding rationale to choose the right protective measure.Fully considered De Warrd proposed that the the influence of product film to CO₂ corrosion, the corrosion product film influence coefficient and Norway' s Norsok model which proposed for a foundation, establishes a CO₂ corrosion forecast model to be applicable to broad scope, and confirms the forecast result with corrosion test data.