Abstract:
The high temperature and high pressure autoclave was used to simulate the working conditions of CO
2 auxiliary steam drive oil gas injection well. The coupon corrosion test was conducted on N80 steel at 160℃ and CO
2 partial pressures of 1-4 MPa, and the effect of CO
2 partial pressure on corrosion behavior of N80 steel was studied. The results show that with CO
2 partial pressure increasing, the corrosion rate increased first and then decreased; when the CO
2 partial pressure was 2 MPa, the corrosion rate reached the maximum value of 0.073 7 mm·a
-1. The main composition of corrosion products of N80 steel was FeCO
3 and a small amount of Fe
2O
3. With the increase of CO
2 partial pressure, the size of FeCO
3 crystals decreased, and FeCO
3 crystals mixed together when CO
2 partial pressure was 3-4 MPa. Under the test condition, the corrosion rate of N80 steel was 0.034 7-0.073 7 mm·a
-1 which was lower than the corrosion rate control line of oil field (0.076 mm·a
-1) and met the property requirement of CO
2 auxiliary steam drive oil well casing.