Study On Corrosion Damage Behavior Of P110S And 13Cr Typical Tubing Materials

The corrosion of oil pipeline steel has always been a key problem restricting China’s oil and gas development.The research on the corrosion of pipeline steel and the development of corrosion resistant alloy in extreme environment are very important.In this study,the corrosion damage behavior of P110S carbon steel and 13Cr stainless steel in oil well extreme environment was systematically investigated and analyzed by simulating the extreme working environment of field tubing at different well depths by experiments such as immersion experiment,optical and electron microscope,X-ray diffraction,corrosion weight loss analysis and electrochemical test.The results of P110S steel showed that the enhancement of temperature increased the corrosion rate,accelerated the dissolution of anode and promoted the formation of Fe S corrosion product film on the surface of P110S steel.However,when the temperature increased to a certain extent,a dense Fe CO₃corrosion product film will be formed on the surface so as to prevent further corrosion and reduce the corrosion rate.Temperature can also promote crevice corrosion.Loading stress on P110S steel will lead to the cracking of Fe S product film on the surface,which increases the corrosion rate of P110S steel to a certain extent,and the corrosion degree first increases and then decreases with the improvement of the stress.With the increase of CO₂partial pressure,the corrosion degree of P110S steel is aggravated and the corrosion degree is obvious.CO₂partial pressure promotes the hydrogen evolution reaction on the surface of P110S steel,significantly increasing the corrosion current density and the corrosion rate to reduce the corrosion resistance of P110S steel.The results of 13Cr stainless steel showed that the increase of temperature will accelerate the formation of corrosion product film,which is composed of Fe CO₃and Fe S.The corrosion rate first increases to the peak and then decreases gradually.With the increase of temperature,the depth of crevice corrosion first increased and then decreased.With the increase of loading stress,the corrosion product film cracked,which increased the corrosion rate of 13Cr stainless steel;When the temperature is higher than 120℃,a dense Cr containing product film is formed on the surface of 13Cr stainless steel,furthermore,a certain stress will promote the occurrence of corrosion.When the stress reached a certain degree,increasing the stress will inhibit the corrosion.With the increase of CO₂partial pressure,the corrosion current density of 13Cr stainless steel decreased and the corrosion weakened.With the increase of CO₂partial pressure,carbonate and bicarbonate ions produced in the solution and 13Cr surface formed a more dense Fe CO₃protective film to inhibit the occurrence of corrosion and improve the corrosion resistance of 13Cr stainless steel.