Research On Corrosion Of028Tubing Materials In Ultra-deep Well Nvironment

Aautoclave tests and SEM modern analytical tools were used to study Cl/Co2weightless corrosion law of028steel tubing under the high temperature and pressure environment; and studied the corrosion behavior of028steel tubing under stress conditions and acid fracturing fluid to pitting and crevice corrosion behavior.The results showed that028nickel base alloy has not had the pit corrosion under the simulation corrosion environment, in the liquid phase test, the uniform corrosion rate did not exceed O.lmm/y, the maximal uniform corrosion rate was only0.0184mm/y. As the well depth increased, the temperature and CO2partial pressure increased, the uniform corrosion rate increased. The corrosion rate of the four-spot bend specimen was higher than the one of the coupon specimen. Under the same corrosion condition, the uniform corrosion rate of gas phase was higher than the one of the liquid phase.The results showed that the SCC performance of028steel tubing, with the temperature increased, the pitting sensitivity increased, the SCC sensitivity which induces by the pitting increased. The material did not break when the temperature was150℃, the density of organic salt completion solution was1.8g/cm3, the load stress was75%Ysmin, performed the720h stress corrosion experiment. The material has not produced the microscopic crack with the20times metallurgical microscope, obvious the material has excellent performance against SCC.After the128h residual acid corrosion test and circulating acidification corrosion test under the temperature150℃,pressure5Mpa,local corrosion did not occur either to both the pipe body or coupling, including pitting, crevice corrosion, etc.