Flow Induced Corrosion of API Round Thread Connection

Abstract Reservoirs with high pressure and high temperature (HP/HT) situated in Northeast Sichuan of China contain high content of acidic components such as carbon dioxide, hydrogen sulfide and element sulfur. The developing conditions of these reservoirs become more and more severe for intense corrosion, which gives rise to short service time of well tube. Then serious safety accidents and environment problems would happen frequently. So investigation of corrosion mechanism and preservation technologies of well tube is very important. Previous published papers usually focused on crevice corrosion, bimetallic corrosion and phase-change induced corrosion. However, corrosion channels are generally found in tube connecting, where the flow velocity is smaller than that in tube. This phenomenon may be explained by the flow induced corrosion. So in this paper, based on the computation fluid dynamics, governing equations of flowing fluid have been bulit. Then flow characteristics in the connection of API round thread tube were simulated. Flow field accompanied by the occurrence of vortex is changing in the tube connection, resulting in accelerated corrosion reaction, cavitation corrosion and erosion-corrosion. As time goes on, morphology of flow induced corrosion would in turn affect the flow rate, which intensifies the corrosion. Finally, some technical measures to reduce flow induced corrosion were proposed. Calculation results of this paper can provide some references to design safe well tubes and operating parameters.