Study On The Corrosion Of Carbon Steel In Supercritical CO₂,Crude And Water Conditions

Global warming and oil energy crisis has become increasingly concerned about the problem of the international community.Global warming is mainly related to the emission of CO₂,the petroleum energy crisis rely on exploration of new energy and improve the oil recovery rate to solve.In the process of oil production,the corrosion of CO₂ is inevitable which causing serious economic losses.Thus,it is really meaningful to study on the corrosion of carbon steel in supercritical CO₂,crude and water conditions.The present study investigated the corrosion of N80 steel and P110 steel in CO₂ environments.The crude was brought from Chunliang Oil Production Plant of Shengli oilfield.According to the mineral content of the formation water in the oil production plant,the water solution was formulated with the reagent of distilled water and chemical analysis.Numerical simulation was used to calculate the distribution characteristics of fluid velocity,turbulent kinetic energy and turbulent intensity at different locations in high pressure autoclave.After the high temperature and high pressure CO₂ corrosion test,utilizing materials analysis techniques of SEM,EDS and Metallurgical Microscope to investigate and analyze experimental data.An idea for reducing corrosion by entraining water in oil was suggested.At the same time,the water content and the stability of emulsion were also the decisive factor of the corrosion.Under the two conditions,the liquid droplets size in different water content were not the same and lead to differents in the rate of corrosion and corrosion product film morphology.When the water content was less than 70%,formed water in oil emulsion and the corrosion rate of carbon steel increased slowly.When the water content was more than 70%,formed oil in water emulsion and the corrosion rate of carbon steel increased rapidly.Under the condition of high speed,the volume expansion of crude oil and water droplets wrapped in crude oil which reduced the contact with the metal matrix.Under the low speed,the emulsion was unevenly distributed and water droplets would be deposited.The droplets would gradually become larger,resulting inhigher corrosion rate and larger pit diameter.