Corrosion features and corrosion control technologies in high-sulfur gas fields
Hu Yongbi1,2,Gu Tan1,2(1.Natural Gas Research Institute of Southwest Oil & Gasfield Company,PetroChina,Chengdu,Sichuan 610213,China;2.Pilot Test Base for the Production of High-Sulfur Gas Reservoirs,Chengdu,Sichuan 610213,China)
The development of high-sulfur gas reservoirs in China is facing such an adverse environment with high contents of H2S and CO2 and a huge volume of field water,which all leads to a serious problem of corrosion in such fields.In view of this,this paper,based on the analysis of corrosion features of high-sulfur gas fields,demonstrates the following advances made over the past years in terms of material selection evaluation,corrosion control by use of inhibitors,corrosion monitoring and detection techniques.(1) Many innovative methods are presented including the Ni-based alloy evaluation,testing on environmental stress cracking resistance and anti-corrosion property for bi-metal composite pipes and welding joints,and the selection and evaluation of inhibitors.(2) The patent of inhibitor CT2-4 water soluble annulus protection fluids can effectively protect the casing wall and outer wall of tubings;with the help of the inhibitor CT2-19,ground pipeline pig pre-filming and continuous inhibitor filling,the corrosion can be controlled well in the humidity airtight conveying system.(3) FSM,hydrogen probe technology,and electrochemical technology as corrosion monitoring assistance have unique advantages especially in the study of corrosion by pitting,crevice corrosion and hydrogen induced cracking corrosion.Finally this paper suggests that corrosion control design and corrosion monitoring system should be introduced early into the programming of developing a high-sulfur gas field.That is,an overall control prevention and control scheme is first planned via the integration and optimization of corrosion control techniques;a digital management system and database is then built for the tracking assessment of inhibitor effects,thereby to achieve a complete design and integrity management of corrosion prevention and control.